JP2003143236A - Gateway - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a LAC (L2TP ACCESS Concentrator) use gateway that can relieve Web traffic in an access network of an ISP selection type IP network. SOLUTION: The gateway 104 connected to the access network 105 containing a plurality of ISP networks 108 and provided with a LAC function that transfers a PPP frame received from a user terminal to the ISP networks via an L2TP connection set onto the access network, includes: a cache server interface 112 to be connected to a Web cache server; and packet transfer controllers (81A to 81C, 87) that select the PPP frame including a request message of Web contents in its payload part among a PPP frame stream received from the user terminal and transfer the request message denoted by the PPP frame to the cache server via a cache server interface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gateway device connected to a plurality of user terminals, and more specifically,
Multiple ISPs (Internet Se
rvice Provider) network is connected by one access network, and the user terminal connects the access network and any one of the above ISs.
LAC (L2 applied to the ISP selection type IP network that accesses the Internet through the P network
The present invention relates to a gateway device having a TP access concentrator) function.

[0002]

2. Description of the Related Art In an era in which 70% or more of Internet traffic is occupied by Web access traffic, speeding up Web access from a user terminal and reducing traffic on a network connecting the user terminal and the Web server are being promoted. Web caching technology is being actively researched with the aim.

In the Web caching technology, a Web cache server (or a Web caching server) is installed in an access network accommodating user terminals,
We part of the content data provided by the Web server
b. By holding the cache data in the cache server and delivering the content data from the Web cache server to the user terminal instead of the Web server, the Web access from the user terminal is speeded up.
It is possible to reduce the traffic on the core network to which the Web server is connected.

Conventionally, in the field of networks for Internet access, each ISP has dispersed its own service area and installed its own access points. However, as a recent tendency, a communication carrier manages a plurality of ISP networks. By connecting to a regional IP network (or a wide area IP network) and arranging a gateway device which is an access point common to the plurality of ISPs on the regional IP network, user terminals connected to the respective access points are arranged. IS connected to any of the above ISP networks
P-selective IP networks have become promising.

In the ISP selection type IP network, a gateway device called LAC (L2TP Access Concentrator) is installed at a connection point between a regional IP network as an access network and a user terminal, and the regional IP network and each ISP are installed.
At the connection point with the network, LNS (L2TP Network Ser
A gateway device called ver) is installed. We
The user terminal that accesses b transmits PPP to the LAC.
Set up a connection. The above PPP connection is
The LAC function connects to the ISP network designated by each user via the L2TP connection established between the LAC and the LNS.

That is, when the user terminal inputs the user ID and the identifier of the connection destination ISP at the time of setting the PPP connection, the LAC connected to the user terminal causes the LN corresponding to the connection destination ISP based on the ISP identifier.
PP set between the user terminal and LAC by specifying S
P connection is set to L between the above LAC and LNS
Extend to a specific LNS via a 2TP connection. Each LNS authenticates the terminal user according to the user ID and determines whether or not the connection between the user terminal and the ISP is possible.
In addition, the extension of the PPP connection by L2TP and LA
The functions of C and LNS are shown in IETF draft RFC2661.

[0007]

In the above-mentioned ISP selection type IP network, an access network (regional IP network or wide area I network) connecting the LAC and each LNS is used.
In order to reduce the communication cost in the P network), there is a need to reduce the traffic between the LAC and each LNS as much as possible. In order to reduce the traffic on the access network, for example, the Web cache server connected to each LNS in the conventional network is set to L.
A network configuration is conceivable in which the Web cache server moves to the AC side and the Web cache server responds to the Web access of each user terminal at the entrance of the access network.

However, in the conventional L2TP type access network, each IP packet sent from the user terminal is transferred to the connection end along the preset PPP connection.
A specific IP packet cannot be branched in the middle of a PPP connection. That is, the conventional gateway device operating as the LAC merely relays the received PPP frame including the IP packet sent from the user terminal to the access network side along the PPP connection, and has the packet processing function at the IP level. Not prepared.
Therefore, in the related art, it is impossible to distribute the web access request to the web cache server at the entrance of the access network and make the web cache server respond.

An object of the present invention is to provide a gateway device for LAC which can reduce Web traffic in an access network of an ISP selection type IP network. Another object of the present invention is to connect a PPP connection to a We
b Extract IP packets for traffic and
It is to provide a gateway device for LAC having a function of transferring to a cache server.

[0010]

In order to achieve the above object, the present invention is connected to an access network accommodating at least one ISP (Internet Service Provider) network connected to the Internet, and received from a user terminal. L2TP (Layer2 Tun) in which a PPP (Point to Point Protocol) frame is set on the access network
LAC (L2TP Access Concentrat) that transfers data to the ISP network via a neling Protocol (neling Protocol) connection.
In a gateway device having an (or) function, a cache server interface for packet communication with a cache server that holds a part of content data provided by the Web server connected to the Internet as cache data, and a cache server interface for receiving from a user terminal. A PPP frame including a request message for Web content in the payload part is selected from the PPP frame sequence, the request message indicated by the PPP frame is transferred to the cache server via the cache server interface, and the cache server interface is Packet transfer control means for transferring the response message received from the cache server via the above to the user terminal of the Web content request source in the PPP frame format.

Further, the present invention is connected to an access network accommodating a plurality of ISP networks connected to the Internet, and a PPP frame received from a user terminal is sent to the user via the L2TP connection set on the access network. LA that transfers to any one of the above ISP networks corresponding to the ISP to which the user of the terminal subscribes
In the gateway device having the C function, the cache server interface for packet communication with the cache server that holds a part of the content data provided by the Web server connected to the Internet as cache data and the subscriber ISP are different. A PPP frame having a payload content request message is selected from a plurality of PPP frames received from a plurality of user terminals, and the request message indicated by the PPP frame is transferred to the cache server via the cache server interface. The IP packet including the response message received from the cache server via the cache server interface.
And a packet transfer control unit for transferring to the user terminal of the Web content request source in the PP frame format.

In one embodiment of the present invention, the packet transfer control means determines the relationship between the destination address of the IP header included in each PPP frame received from the user terminal and the specific IP address assigned to the cache server. By checking, identify the PPP frame containing the web content request message.

In another embodiment of the present invention, the packet transfer control means checks the upper layer protocol of the IP packet included in each PPP frame received from the user terminal, thereby determining the PPP frame including the Web content request message. Identify. For example, TCP (Transmission Co) of the IP packet included in each PPP frame
ntrol Protocol) or UDP (Use Datagram Protoco)
Check the port number in l), and if the port number is H
"8" indicating TTP (Hyper Text Transfer Protocol)
The received PPP frame with "0" is determined as the PPP frame for the Web content request message. Other objects and characteristics of the present invention will be apparent from the description of the embodiments of the invention described below.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. The first embodiment of the present invention is LA
In an ISP selection type IP network system in which packet communication between C and each LNS is performed by L2TP, a Web cache server is connected to a gateway device that functions as a LAC, and an IP for Web traffic transmitted from a user terminal is sent. It is characterized in that the packet is transferred from the gateway device to the Web cache server by a proxy setting method.

FIG. 1 shows an example of an ISP selection type IP network system to which the gateway device of the present invention is applied as the LAC 104. The LAC (gateway device of the present invention) 104 is, for example, a telephone network, ADSL, or CATV.
Are connected to a plurality of user terminals 101-1 to 101-m via access lines 102-1 to 102-m, and a plurality of LNs via a regional IP network (or wide area IP network) 105.
It is connected to S107-1 to 107-n.

The LNSs 107-1 to 107-n are respectively connected to the ISP networks 108-1 to 108-n, and the ISP networks 108-1 to 108-n are connected to the Internet 1 via the routers 109-1 to 109-n.
Connected to 10. Although only one Web server 111 is shown here, the Internet 110
A plurality of servers accessible from the user terminal, such as a mail server and other Web servers, are connected to the server.

Each ISP network 108-1 to 108
-N is a RADIUS for authenticating the ISP subscriber.
US (Remote Authentication Dial In User Service)
Servers 120-1 to 120-n, DNS (Domain Name System) servers 130-1 to 130-n for searching IP addresses from host names, and DHCP (not shown)
(Dynamic Host Configuration Protocol) Server is connected. Further, the LAC 104 has a LAN 112.
The Web cache server 113 and the RADIUS server 114 for performing the primary authentication of the user are connected via the.

Regional IP serving as the Internet access network
LAC 104 and LNS 107-1 connected to network 105
To 107-n, the IP address “192.168.0.
128 ”,“ 192.168.0.1 ”to“ 192.168.0.n ”are assigned. Also, in the Web cache server 113,
An IP address corresponding to each ISP (ISP network and RADIUS server) is assigned.

In the illustrated example, one Web cache server 113 is connected to the ISP networks 108-1 to 108.
Multiple IP addresses corresponding to -n ("210.10.10.1"
~ "210.10.10.n"), and as will be described later, when the Web cache server 113 obtains the Web content requested by the user from the Web server 111, an HTTP request message (which is sent to the Web server) ( The source address of the IP packet) is properly used according to the joining ISP of the request source user. still,
Although only one LAC 1104 is shown in FIG. 1, a large number of LACs each accommodating a plurality of user terminals are connected to the actual regional IP network 105.

Next, referring to FIGS. 2 to 4, in the ISP selection type IP network system, the connection for accessing the Internet 110 from the user terminal 101-1 contracting with the provider of the ISP network 108-1. I will explain the transition of. The user terminal 101-1 is, as shown in FIG.
-1 through PPP (Point to Point to LAC 104)
Point Protocol) Connection 103-1a is set. On the PPP connection, the PPP frame 200
Data is transferred in the following format.

As shown in FIG. 5A, the PPP frame 200 has an information field 2 in which an IP packet is set.
Before 05, there is a PPP header consisting of a flag field 201, an address field 202, a control field 203, and a protocol identification field 204, and after the information field 205, a PAD field 206.
, FCS field 207, and flag field 20
Including 8.

The data type of the information field 205 is identified by the protocol identification field 204. FIG. 5B shows the relationship between the typical identification value 204 set in the protocol field 204 and the protocol 204A.

IPCP (Intern) is used to transfer IP packets.
et Protocol Control Protocol) is applied, and IP packets are transmitted after performing IP negotiation such as transmission / reception of IP addresses at both nodes of the PPP connection. Further, in order to suppress the overhead of data transmission by the PPP header, the address field 202 and the control field 203 are compressed, and the protocol field 204 is compressed (for example, the protocol identification value is 00FFh.
(Only the lower 1 byte is transmitted only when it is smaller), and the option used on the PPP connection is LC at both nodes of the PPP connection.
It is determined by negotiation by P (Link Control Protocol).

Upon receiving the LCP control data (link setting request) in the PPP frame from the user terminal 101-1, the LAC 104 communicates with the user terminal LCP control data for option setting negotiation to establish a link. After that, the user terminal 101-1 is, for example, PAP (Password Authentication Protocol),
CHAP (Challenge Handshake Authentication Proto)
The user name information and password are transmitted to the LAC 104 by an authentication protocol such as col).

The LAC 104 RAD these data.
Transfer to IUS server 114, RADIUS server 11
4 request the user's primary authentication. When the RADIUS server 114 sends a response indicating successful authentication, the LAC
104 indicates, for example, from the user name information, the user terminal 101.
The ISP to which -1 belongs is identified, and the LNS 107-1 corresponding to the ISP is specified.

The LAC 104 transmits / receives the L2TP control message 300 to / from the LNS 107-1 so that the LAC 104 and the LNS 107 are connected as shown in FIG.
After setting the L2TP connection 106-1 with -1, the user session is established. By this, L
The tunnel ID of the 2TP connection 106-1 and the session ID are determined.

The LAC 104 uses the L2TP connection 1
The LCP information and the authentication information (user name / password) for setting the PPP option described above are transmitted to the LNS 107-2 via 06-1. Based on the LCP information, the PPP option is negotiated between the LAC 104 and the LNS 107-2. In addition, the authentication information is transferred to the RADIUS server 120-1,
User authentication is performed in the RADIUS server 120-1. By the above procedure, L2TP connection 1
The PPP connection 103-1b for the user terminal 101-1 is set on 06-1.

In FIG. 3, the user terminal 10 is shown for convenience of explanation.
PPP connection 10 between 1-1 and LAC 104
Although a different code is given to the 3-1a and the PPP connection 103-1b between the LAC 104 and the LNS 107-1, in reality, the tunnel ID and the session of the L2TP connection 106-1 assigned when the user session was established. By managing the ID in association with the PPP connection 103-1a, the LAC 104 manages the P
PP connection 103-1b and PPP connection 1
03-1a is managed by the same connection identifier.

The user terminal 10 using the HDCP server
The dynamic allocation of the IP address to 1-1 is performed by the above PP.
This is performed after setting the P connection 103-1b. This causes the user terminal 101-1 to communicate with the PPP connection 103-1 (103-1a and 103-1b) and the IS.
Internet 1 via P network 108-1
10 can be accessed.

FIG. 4 shows user terminals 101-1 and 101-.
2, 101-m indicate PPP connections when they are respectively joined to different ISP networks. In this example, the PPP connection 103-2a between the user terminal 101-2 and the LAC 104 is extended to the LNS 107-2 by the PPP connection 103-2b on the L2TP connection 106-2, and the user terminal 101-m.
Connection 103-m between the LAC and the LAC 104
a shows a state in which the PPP connection 103-nb on the L2TP connection 106-n is extended to the LNS 107-n. The PPP connection 103 (103-1b to 103-nb) for the user terminal is set according to the need of the user and is canceled when it is no longer needed.

In the ISP selection type IP network of the present invention, on the L2TP connections 106-1 to 106-n between the LAC 104 and the LANs 107-1 to 107-n, in addition to the PPP connection 103 for the user terminal, the Web The PPP connection 116 (116-1 to 116-n) for the cache server 113 is set.
These PPP connections 116 are set when the Web cache server 113 is started up, and exist constantly.

A feature of the present invention is that the LAC 104 is a Web
Each user terminal 101 (10
1-1 to 101-m) is the PPP connection 103 (1
03-1a to 103-ma) to capture the HTTP request message and transfer it to the cache server 113,
The HT is sent from the cache server 113 to the requesting user terminal.
The reason is that the TP response message is returned.
The cache server 113 uses the We requested by the user.
b Only when the content does not exist in the cache data, the PPP connection 116 (116
-1 to 116-n) is used to acquire the Web content from the Web server 111 and transfer the Web content to the requesting user terminal.

According to the above configuration, direct communication between the user terminal and the Web server 111 is suppressed, so that the regional IP network 1 that serves as an access network to the Internet 110.
The traffic volume of the HTTP request message and the HTTP response message in 05 can be significantly reduced.

Next, in the above network, the packet transfer sequence when the Web browser application running on the user terminal 101-1 acquires the Web contents will be described in more detail. First, in order to facilitate understanding of the present invention, FIG.
A packet transfer sequence when the LAC 104 shown in FIG. 1 is configured by a conventional gateway device will be described with reference to FIG. Here, FIG. 6B
6 shows the relationship between the destination address DA and the source address SA set in the IP header in the transfer packet shown in FIG. 6 (A).

The user of the terminal 101-1 uses the URL (Uniform Resource I) for the content data to be obtained from the Web server 111 in the Web browser application.
When specified by the dentifier (S1011), the HTTP request message addressed to the Web server 111 including the above URL is transmitted from the user terminal 101-1 to the access line 102-1. The HTTP request message above is
I with the IP address of the Web server 111 as the destination address and the IP address of the terminal 101-1 as the source address
The packet is transmitted to the access line 102-1 in the form of a PPP frame 601 in which the PPP header is added to the IP packet having the P header IP (a).

The LAC 104 is the access line 102-1.
The PPP frame 601 received from the IP having the L2TP header, the UDP header, and the new IP header IP (b)
It is converted into a packet 602 and transferred to the L2TP connection 106-1 heading for the LNS 107-1. The destination address of the IP header IP (b) is the IP address of the LNS 107-1, and the source address is the IP of the LAC 104.
The address is set.

The IP packet 602 is the local IP network 1
05 is routed to reach LNS 107-1. The LNS 107-1 sends the L2T to the IP packet 602.
P termination processing (removing the IP header, UDP header, and L2TP header) and PPP termination processing (removing the PPP header) are performed, and the IP packet 603 having the IP header IP (a) is returned to the ISP network 108- Send to 1. The IP packet 603 is relayed from the ISP network 108-1 to the Internet 110 via the router 109-1 and transferred to the Web server 111.

The Web server 111 extracts the HTTP request message contained in the data part of the received IP packet 603, and retrieves the content data specified by the URL of the HTTP request message. HT including search results
The TP response message is the requesting user terminal 101.
-1 IP address as destination address, Web server 11
IP header I whose source address is the IP address of 1
The IP packet 604 having P (c) is transmitted to the Internet 110 and reaches the LNS 107-1 via the router 109-1 and the ISP network 108-1.

The LNS 107-1 receives the received packet 604.
The PPP connection is specified from the destination address of the received packet 604, and the received packet 604 is set to the PPP header, L2TP header,
IP with P header and new IP header IP (d)
Converted to packet 605, L2TP connection 10
6-1. The destination address of the IP header IP (d) is the IP address of the LAC 104, and the source address is the IP address of the INS 107-1.

The LAC 104 subjects the IP packet 605 received from the regional IP network 105 to L2TP termination processing, converts the received packet 605 into a PPP packet 606, and transfers the PPP packet 606 to the access line 102-1. The PPP packet 606 is received by the user terminal 101-1 and the HT is transmitted by the Web browser application.
The content data extracted from the TP response message is displayed on the terminal screen (S1012).

As the above sequence shows, the conventional I
In the SP selection type IP network, the Web server 111
When acquiring the content data provided by the user terminal 10, the HTTP request message transmitted from the user terminal 101-1 is transferred to the Web server 111 via the access network 105 (PPP connection 103-1) and the ISP network 108-1. , Web server 11
1 is a response message from the ISP network 108.
-1 and the access network 105 to be transmitted to the requesting user terminal. That is, the conventional LAC10
4 is an HTTP request message (PP
P frame) is simply L on the access network 105 side
It only relays to the 2TP connection and does not have an IP packet routing function according to the IP header in the PPP frame.

Next, a packet transfer sequence when the gateway device of the present invention is applied to the LAC 104 will be described with reference to FIGS. 7 and 8. In this embodiment, LAC1
04 user terminals 101-i (i = 1 to −)
m), the IP address of the Web cache server 113 corresponding to the ISP to which each terminal user subscribes is added to the Web browser application running on
It is assumed that the proxy server address is set in advance. Therefore, the HTTP request message is I
The packet is sent from each user terminal to the LAC 104 as a PPP packet including the IP address of the Web cache server 113 in the destination address field of the P header.

In the present embodiment, the LAC 104 checks the destination IP address of the packet received from the access line 102-i (i = 1 to m) and routes the received packet according to the destination IP address. The IP packet including the HTTP request message is transferred from the LAC 104 to the web cache server 113, and the content data designated by the URL is stored in the web cache server 1.
If it exists in 13, the response message including the designated content data is returned from the Web cache server 113 to the requesting user terminal.

FIG. 7A shows a packet transfer sequence when the content data designated by the URL exists in the Web cache server 113, and FIG. 7B shows the packet transfer sequence in FIG. IP in the transfer packet shown in
The relationship between the destination address DA and the source address SA set in the header is shown.

When the user specifies the URL of the content data for the Web browser application running on the user terminal 101-1, a PPP frame 701 including an HTTP request message is generated, and the user terminal 101-1 accesses the access line. 102-1 is transmitted (S1011). As the destination address of the IP header IP (e) of the PPP frame 701, the Web cache server IP address corresponding to the specific ISP to which the terminal user subscribes is automatically set by the proxy setting of the Web browser application described above. Is set. The destination address is, for example, one of a plurality of IP addresses “210.10.10.1” to “210.10.10.n” assigned to the Web cache server 113 in FIG.

The LAC 104 uses the PPP frame 70.
1 is received, an IP packet 702 is received from the received frame.
And the destination address of the IP header IP (e) is LA
Web cache server 113 registered in advance in C
Of the assigned IP address. The destination address is
When the IP address assigned to the Web cache server 113 matches, the LAC 104 sends the IP packet 7
02 is transferred to the Web cache server 113. Allocation I of the destination address of the Web cache server 113
If it does not match the P address, the LAC 104 sends the received PPP frame 701 to the PPP on the local IP network 105 side.
Relay to connection 103-1b.

The Web cache server 113 is a LAC
When the IP packet 702 is received from 104, the HTTP request message is extracted from the data part, and the content data specified by the URL is searched from the cache data (S1131). When the specified content data is found, an HTTP response message including the content data is generated (S1132), the HTTP response message is included in the data portion, and the requesting user terminal 101 is included.
The IP packet 703 whose destination address is the IP address of −1 is sent to the LAC 104.

Since the destination address of the received packet 703 from the Web cache server 113 indicates the user terminal 101-1, the LAC 104 receives the received packet 70.
3 to access line 102 in the form of PPP frame 704
Transfer to -1.

FIG. 8A shows a packet transfer sequence when the content data specified by the HTTP request message does not exist in the Web cache server 113. 8B shows the destination address DA set in the IP header in the transfer packet shown in FIG.
And the source address SA.

As in the case of FIG. 7A, the LAC 104
Upon receiving the PPP frame 701 including the HTTP request message from the access line 102-1, determines the destination address of the IP header IP (e) and transfers the IP packet 702 to the Web cache server 113.

The Web cache server 113 extracts the HTTP request message from the data part of the received packet 702 and retrieves the content data designated by the URL from the cache data (S1131). Search results,
If the specified content data is not in the cache data, the Web cache server 113 determines the U
The DNS server 130-1 is inquired about the IP address of the Web server 111 having the RL host name (S113).
3). When the IP address of the web server 111 is known, the web cache server 113 sets an IP packet 705 in which the HTTP request message is set in the data section.
Is generated and transmitted to LAC1-4.

Header IP of the IP packet 705
In (g), the Web cache server 113 whose destination address is the IP address of the Web server 111 and whose source address is the destination address of the PPP frame 701.
Is the assigned IP address.

Upon receiving the IP packet 705 from the Web cache server, the LAC 104 identifies the destination LNS from the source address of the received packet. In this example, the destination LNS is 107-1. LAC104 is
The IP packet 705 is converted into the IP packet 706, and the L2TP between the LNS 107-1 and the LAC 104 is converted.
PPP connection 116 on connection 106-1
Transfer to -1.

The IP packet 706 is the same as the received IP packet 706 except that the PPP header, the L2TP header, and the UDP
Header, IP header IP (h) is added,
The destination address of the IP header IP (h) is LNS107-
1 is the IP address and the source address is LAC104 I
It is a P address. The IP packet 706 is
The LNS 107-1 performs termination processing of L2TP and PPP, returns the original IP packet 705 sent by the Web cache server 113, and transfers it to the Web server 111 (707).

In the Web server 111, the received packet 7
The HTTP request message is extracted from the data part of 05,
Search the content data specified by the URL (S11
11), the HTTP response message including the designated content data as an IP packet 708 on the Internet 11
Send to 0. IP header I of the IP packet 708
In P (i), the IP address of the Web cache server 113 is used as the destination address and We is used as the source address.
b The IP address of the server 111 is set.

The IP packet 708 is the LNS 107.
-1 received, PPP header, L2TP header, UD
It is converted into an IP packet 709 to which the P header and the IP header IP (j) are added, and is sent to the L2TP connection 106-1 of the regional IP network. The IP header IP (j)
Indicates that the destination address is the IP address of the LAC 104 and the source address is the IP address of the LNS 107-1, and the IP packet 709 is the L address in the LAC 104.
After termination of 2TP and PPP, the packet is returned to the original IP packet 708 and then transferred to the Web cache server 113 according to the destination address of the IP header IP (i).

The Web cache server 113 extracts the HTTP response message from the data section of the received packet 708, stores the Web content data included in the response message as cache data, and then requests the content terminal user terminal. H addressed to 101-1
A TTP response message is generated (S1134), and this is sent to the LAC 104 as an IP packet 703. L
In the AC 104, the destination address of the IP packet 703 received from the Web cache server 113 is the user terminal 1
Since the IP address is 01-1, the received packet is converted into the PPP frame 704, and the user terminal 101
-1 access line 102-1.

FIG. 9 is a block diagram showing an embodiment of the gateway device according to the present invention having the function of the LAC 104 described above. The gateway device (LAC) 104 is
A plurality of access line interface circuits 80A respectively accommodating the access lines 101-i (i = 1 to m),
A Web cache server interface circuit 80B connected to the LAN 112, a regional IP network interface circuit 80C connected to the regional IP network 105, and protocol processing circuits 81A, 81B, 81C provided corresponding to these interface circuits, Internal switch circuit 87 for exchanging packets between these protocol processing circuits
And a node control circuit 88 connected to each of the protocol processing circuits.

The interface circuits 80A to 80C send and receive packet data according to the physical line type (for example, Ethernet (registered trademark), ATM, etc.) of the network accommodated therein. Protocol processing circuit 81A
81C have a protocol processing function corresponding to the interface circuits 80A, 80B, 80C to which they are respectively connected, as described later. In FIG. 9, one protocol processing circuit 81A is connected to each access line interface circuit 80A, but a plurality of access line interface circuits 80A are connected to each protocol processing circuit 81A via a packet multiplexing / distributing device. It is also possible to

The internal switch circuit 87 switches the packet input from the protocol processing circuits 81A to 81C to one of the protocol processing circuits specified by the transfer destination information of the internal header. The node control circuit 88 controls the entire operation of the gateway device according to the setting information input from the control terminal 90, and outputs an alarm and statistical information to the control terminal 90.

FIG. 10 shows a protocol processing circuit 81 (81
The basic structure of A to 81C) is shown. The protocol processing circuit 81 includes a CPU 811, a memory 812, an interface reception buffer 813, an interface transmission buffer 814, an internal switch transmission buffer 815, an internal switch reception buffer 816, and an inter-CPU communication interface circuit 817, which are connected to each other. Even if the type of the interface circuit used is different, the hardware has the same configuration.

The memory 812 has a program storage area 8
20, user terminal information management table 830, and ISP
An information management table 840 and an HTTP request message management table 850 are arranged. However, the HTTP request message management table 850 is the second
It is a table required in the embodiment and is unnecessary in the first embodiment of the present invention described below. The program storage area 820 stores a program corresponding to the function (81A, 81B, 81C) of the protocol processing circuit as described later, and by executing the prepared program by the CPU 811, the corresponding interface circuit and Predetermined protocol processing is performed on the data transmitted and received between the two.

The CPU 811 has another protocol processing circuit and the node control circuit 8 constituting the gateway device 104 via the inter-CPU communication interface circuit 817.
The management information, alarms, and statistical information necessary for protocol processing are transmitted to and received from the server 8.

Interface circuit 80 (80A-80)
The packet data (IP packet or PPP frame) received in C) corresponds to the corresponding protocol processing circuit 81.
(81A to 81C) and is temporarily stored in the interface reception buffer 813 shown in FIG. The packet data accumulated in the interface reception buffer 813 is subjected to a predetermined protocol process defined by a reception packet processing routine prepared in the memory area 820 by the CPU 811, and then the internal switch transmission buffer 815 is used to transmit the packet data. 87 is input.

The packet data received from the internal switch 87 is temporarily accumulated in the internal switch reception buffer 816, and subjected to the predetermined protocol processing defined by the transmission packet processing routine prepared in the memory area 820 by the CPU 811. Then, via the interface transmission buffer 814, the corresponding interface circuit 80
(80A to 80C).

FIGS. 11A to 11E show packet formats transferred between the interface circuit 80 and the protocol processing circuit 81. (A) is a PPP frame including LCP control information in the payload section 1003,
(B) shows a PPP frame including NCP control information in the payload section 1003, and (C) shows an IP header 1005 and an HTTP request message 1006 in the payload section 1003.
A PPP frame including and, (D) is a payload part 10
03 with IP header 1005 and HTTP response message 1
(E) indicates a PPP frame including the IP header 1005 in the payload portion 1003 and non-HTTP data 1008 such as e-mail and Telnet.

In the PPP frame, each interface circuit 80 (80A-80C) causes the PPP header 10
A PPP connection identifier 1001 is added before 02. However, when the received data is not associated with a specific PPP connection, a predetermined magic number indicating an unspecified PPP connection is added as the identifier 1001.

In the conventional LAC, the PPP header 1002
The protocol information included in the LCP or NCP in the payload section 1003 as shown in (A) and (B).
For frames containing control information of
P processing or NCP processing is being executed, but (C) ~
As shown in (E), a PPP frame including an IP packet in the payload section 1003 is simply treated as user traffic data, and has only the function of relaying the received frame to the output network side along a predesignated PPP connection. It was

On the other hand, in the LAC of the present invention, when the PPP frame received from the access line or the IP network includes an IP packet (user traffic data) in the payload section 1003, the access line compatible protocol processing section 81A and the IP network compatible The protocol processing unit 81C checks the destination address of the IP header 1005, and if the IP packet is for HTTP traffic, the received IP
The packet is separated from the PPP connection and transferred to the cache server 114 connected to the LAC.

FIG. 12 shows the protocol processing unit 81 (81A).
81C) and the internal switch 87. Each protocol processing circuit 81 receives a packet (PPP connection identifier 1001) from the interface circuit 80 (80A to 80C).
Is output to the internal switch 87 in a form in which an internal header 1010 including internal transfer destination information is added. PPP attached to received packet
The connection identifier 1001 is the protocol processing circuit 8
In No. 1, it is rewritten as necessary. The internal switch 87 switches the packet received from each protocol processing circuit 81 to any other protocol processing circuit 81 specified by the internal transfer destination information (internal header) 1010.

FIG. 13 shows the user terminal information management table 8
30 shows one example. User terminal information management table 8
A plurality of management information entries corresponding to the respective user terminals accommodated in the LAC 104 are registered in 30. Each management information entry includes the IP address 831 of the user terminal and the identifier 83 of the PPP connection between the user terminal and the LNS.
2, ISP identifier 833 to which the user belongs, and PP
PCP connection LCP (Link Control Protocol) setting option information 834 and L2TP connection information 8
35 shows the correspondence with 35.

The LCP setting option information 834 is, for example, protocol field compression (PFC: Protoco).
l Field Compression) Set value 834a indicating whether or not the option is selected, and address / control field compression (AC
FC: Address and Control Field Compression) A set value 834b indicating whether or not the option is selected is included. Further, as the L2TP connection information 835, L2T
Tunnel ID 835a and session ID 83 used when setting the PPP connection in the P connection
Information such as 5b is included.

FIG. 14 shows the ISP information management table 840.
One example of The ISP information management table 840 includes ISs connected to the access network 105.
A plurality of management information entries corresponding to the P network are stored.

Each management information entry has an ISP identifier 84.
1, the IP address 842 assigned to the Web cache server 113, and the IS indicated by the ISP identifier 841.
IP address of the LNS containing the P network 8
43, the LAC-LNS PPP connection identifier 844 used for communication between the Web cache server 113 and the Web server 111, the LCP setting option information 845, and the L2TP connection information 846 are shown. The LCP setting option information 845 and the L2TP connection information 846 include the same information items as the user information management table 830, respectively.

FIG. 15 shows the flow of data inside the LAC 104 of the present invention. The PPP frame input from the access line to the access line interface 80A is processed by the access line compatible protocol processing circuit 81A according to the type of the upper protocol indicated by the protocol field 204. When the upper protocol of the received frame is LCP of PPP, LCP processing is executed, and when it is NCP, NCP processing is executed.

Destination IP if the upper protocol is IP
The address is determined. For example, if the destination address matches the assigned IP address 842 of the Web cache server registered in the ISP management table 840, as in the received frame 701 described in FIG. 8, the IP packet 702 extracted from the received frame. Is transferred to the protocol processing circuit 81B corresponding to the cache server via the internal switch circuit 87. When the upper layer protocol of PPP is other than LCP, NCP, IP, or W
In the case of an IP not addressed to the eb cache server, the received packet is transferred to the protocol processing circuit 81C compatible with the IP network, and an appropriate L2TP determined by the source IP address is transmitted.
Sent to the connection.

I received by the cache server protocol processing circuit 81 B from the Web cache server 118
The P packet is distributed to the access line compatible protocol processing circuit 81A or the IP network compatible protocol processing circuit 81C according to the destination IP address.

For example, the IP packet 70 described with reference to FIG.
3, the received packet whose destination IP address matches the IP address 831 of any user terminal registered in the user information management table 830 is determined to be an IP packet including an HTTP response message, and access line compatible protocol processing is performed. It is transferred to the circuit 81A. Also, FIG.
The received packet whose packet destination IP address does not correspond to any of the user terminal IP addresses registered in the user information management table 830 like the IP packet 705 described in 1. is determined to be an IP packet including an HTTP request message, It is transferred to the network compatible protocol processing circuit 81C.

The L2TP frame received by the interface 80C from the IP network is terminated by the protocol processing circuit 81C corresponding to the IP network, and the received IP packet extracted from the L2TP frame is processed by the access line corresponding protocol according to the identifier of the PPP connection. It is distributed to the circuit 81A or the cache server compatible protocol processing circuit 81B. For example, the IP packet transferred on the PPP connection set between the user terminal and the LNS is sent to the access line compatible protocol processing circuit 81A, and on the PPP connection for the cache server set between the LAC and LNS. The transferred IP packet has a cache server compatible protocol processing circuit 81B.
Transferred to.

FIG. 16 shows a flow chart of a received packet processing routine 1500 executed by the CPU 811 of the access line protocol processing circuit 81A. In the reception packet processing routine 1500, first, the reception packet shown in (A) to (E) of FIG. 11 is taken out from the interface reception buffer 813, and the format of the PPP header 1002 is specified (S1501). The format of the PPP header can be specified by referring to the user terminal management table 830 based on the PPP connection identifier 1001 attached to the received packet and reading the LCP setting option information 814 corresponding to the PPP connection identifier.

Next, the upper protocol of the received PPP frame 1003 is identified from the contents of the protocol field 204 of the PPP header. When the upper protocol of the received PPP frame is the data link control protocol: LCP (S1502), LCP packet processing is executed (S
1520). When the upper protocol of the received PPP frame is the network control protocol: NCP (S150
3), NCP packet processing is executed (S1530).

The upper protocol of the received PPP frame is I
In the case of P (S1504), it is checked whether the destination address of the IP header matches the IP address assigned to the Web cache server 113 (S150).
5). Specifically, first, based on the source address of the IP header, the user terminal management table 830 is referred to, and the identifier 833 of the ISP to which the source user belongs is obtained. Next, the assigned IP address 842 of the Web cache server corresponding to the ISP is specified by referring to the ISP information management table 840 based on the ISP identifier, and this IP address is compared with the destination address of the received IP packet. .

If the destination address of the IP header matches the assigned IP address of the Web cache server,
The PPP connection identifier 1001 is added to the received IP packet.
And internal transfer destination information 1010 are added and stored in the internal switch transmission buffer 815 (S1510). in this case,
As the PPP connection identifier 1001, the LAC-LNS PPP connection identifier 844 registered in the ISP information management table 840 corresponding to the ISP identifier.
Is applied, and a value designating the cache server compatible protocol processing circuit 81B is set as the internal transfer destination information 1010.

If the upper protocol of the received PPP frame 1003 is not IP, or if the upper protocol is IP
However, if the destination address does not match the assigned IP address of the Web cache server, the internal transfer destination information 1010 designating the IP network compatible protocol processing circuit 81C is added to the received packet and the internal switch transmission buffer 815 is added. It is stored (S1540). By repeating the execution of the received packet processing routine 1500,
PP sent from user terminals 101-1 to 101-m
PP including HTTP request message in P frame
The P frame can be transferred to the Web cache server 113, and the other PPP frames can be transferred to the IP network 105.

FIG. 17 shows a flowchart of a transmission packet processing routine 1600 executed by the CPU 811 of the access line network compatible protocol processing circuit 81A. In the routine 1600, the transmission packet is extracted from the internal switch reception buffer 815 in the format shown in FIG. 12 (S1601), the packet is transferred to the interface transmission buffer 814 (S1602), and the process is terminated. By repeating the execution of the routine 1600, the HT sent from the Web cache server 113
An IP packet including a TP response message and the IP network 10
It is possible to transfer the IP packet addressed to the user terminal received from the 5 side to the access line interface circuit 80A.

Access line interface circuit 80A
Is the internal transfer destination information 1010 and the PPP from the packet received from the access line compatible protocol processing circuit 81A.
The access line 1 separated from the connection identifier 1001 and connected to the access line interface circuit 80A
Send to 02. For example, when a plurality of connections are multiplexed on one access line 102 like an ATM line, the PPP frame 1103 is sent out on the connection specified by the PPP connection identifier 1001.

FIG. 18 shows a flow chart of a received packet processing routine 1700 executed by the CPU of the Web cache server compatible protocol processing circuit 81B. In this routine 1700, the interface reception buffer 9
The received packet having the format shown in (C) or (D) of FIG. 12 is extracted from 03 (S1701).
The IP packet sent by the Web cache server is P
Since it is not associated with the PP connection,
The packet fetched from the buffer 903 contains the PPP
As the connection identifier 1001, a magic number meaning an unspecified PPP connection is added.

In the routine 1700, next, the destination address included in the IP header 1005 of the received packet is compared with the user terminal IP address 831 registered in the user terminal information management table 830 (S170).
2). If the destination address matches any user terminal IP address, the user terminal information management table 830
The PPP connection identifier 832 is acquired from the entry corresponding to the destination address of the above (S1703), and the received IP packet is converted into a PPP frame according to the LCP setting option information 834 of the above entry (S170).
4). Then, in the PPP frame, the step S
The PPP connection identifier obtained in 1703 and the internal transfer destination information designating the access line compatible protocol processing circuit 81A are added and stored in the internal switch transmission buffer 815 in the frame format shown in FIG. 12 (S1705). .

From the user terminal information management table 830, the user terminal IP address 83 that matches the above destination address.
If 1 is not found, the ISP information management table 840 is searched for an entry whose cache server assigned IP address 842 matches the source address of the received IP packet, and the PPP connection identifier 844 of the entry is acquired (S1706). ). Next, according to the LCP setting option information 845 in the above entry, the reception I
The P packet is converted into a PPP frame (S1707),
The PPP connection identifier acquired in step S1706 and the internal transfer destination information designating the IP network compatible protocol processing circuit 81C are added to the PPP frame, and the internal switch transmission buffer 815 has the frame format shown in FIG. (S1708).

Through the above processing, among the IP packets transmitted by the Web cache server 113, the IP packet addressed to the user terminal which includes the HTTP response message is sent to the access line compatible protocol processing circuit 81A and addressed to the Web server which includes the HTTP request message. IP packet is I
It becomes possible to distribute to the P network compatible protocol processing circuit 81C.

FIG. 19 shows a flowchart of a transmission packet processing routine 1800 executed by the CPU of the cache server protocol processing circuit 81B. Routine 1
At 800, from the internal switch receive buffer 816 to FIG.
Extract the transmission packet in the format shown in 2 (S
1801), an IP packet is extracted from the PPP frame 1103 (S1802). After that, a magic number indicating an unspecified PPP connection is added to the IP packet as the PPP connection identifier 1001 and transferred to the interface transmission buffer (S1).
803). By this processing routine, access line 1
It is possible to transfer the HTTP request message received from 02-1 to 102-m and the HTTP response message received from the IP network 105 to the Web cache server 113.

FIG. 20 shows a flowchart 1900 of the received packet processing routine executed by the CPU of the IP network protocol processing circuit 81C. In the routine 1900, first, the interface reception buffer 813
The packet is taken out (S1901). Interface reception buffer 81 of the IP network compatible protocol processing circuit 81C
The packets stored in No. 3 are in the IP packet format having an IP header at the beginning like the packets 706 and 709 shown in FIG. The IP network interface circuit 80C that receives these IP packets does not have a special function of extracting the PPP header from the received IP packet and checking the upper layer protocol. Therefore, the PPP connection identifier 1001 added to each IP packet by the IP network interface circuit 80C is
It is a magic number that means the unspecified PPP connection.

In the routine 1900, the reception buffer 81
IP packet is extracted from 3 and I is extracted from the IP packet.
The P header and the UDP header are removed, and the L2TP frame is extracted (S1902). Next, from the user terminal information management table 830 and the ISP information management table 840,
The entry having the L2TP connection information 835 or 846 that matches the tunnel ID and the session ID indicated by the L2TP header of the L2TP frame is searched (S
1903).

When the target entry is found in the user terminal information management table 830 (S1904), the above L
A PPP frame is extracted from the 2TP frame (S190
5), in the PPP frame, the PPP indicated by the above entry
The connection identifier 832 and the internal transfer destination information designating the access line compatible protocol processing circuit 81A are added and transferred to the internal switch transmission buffer 815 in the frame format shown in FIG. 12 (S1906).

When the target entry is found in the ISP management information table 840, the PPP frame is extracted from the L2TP frame (S1907), and the PPP connection identifier 844 indicated by the entry and the protocol compatible with the cache server are extracted in the PPP frame. The internal transfer destination information 1010 designating the processing circuit 81B is added and transferred to the internal switch transmission buffer 815 in the format shown in FIG. 12 (S1908).

Through the above processing, among the packets received from the IP network, the PPP frame including the HTTP response message transmitted by the Web server 111 to the Web cache server 113 is transferred to the Web cache server 113 and the other PPP frames are transmitted. Is the destination user terminal 1
It is possible to transfer in the access line direction corresponding to 01-1 to 101-m.

FIG. 21 shows a transmission packet processing routine 2 executed by the CPU of the IP network compatible protocol processing circuit 81C.
000 shows a flow chart. In the routine 2000, the transmission packet of the format shown in FIG. 12 is taken out from the internal switch reception buffer 816 (S200
1) The user terminal information management table 830 and the ISP information management table 840 are searched for an entry having a PPP connection identifier 832 or 844 that matches the PPP connection identifier 1001 attached to the transmission packet (S2002).

When the target entry is found, the values of the tunnel ID and the session ID indicated by the L2TP connection information 835 or 846 of the entry are applied to generate an L2TP header, and the L2TP is sent to the transmission PPP frame 1103.
A header, a UDP header and an IP header are added to form an IP packet (S2003). After that, the PPP connection identifier 1001 is added to the IP packet and transferred to the interface transmission buffer 814 (S200).
4).

By the above processing, the user terminal 101-1
The packets including the HTTP request message transmitted from the Web cache server 113 and the packets other than the Web traffic transmitted from the ‘
It is possible to transfer to each destination via an appropriate L2TP connection on the P network.

Next, the second embodiment of the present invention will be described with reference to FIGS. The second embodiment is the LAC
The gateway device configured by 104 has a function of forcibly transferring a packet (Web traffic) addressed to the Web server transmitted from the user terminal to the Web cache server.

FIG. 22A shows the second embodiment,
22B shows a packet transfer sequence when the content data specified by the URL exists in the Web cache server 113, and FIG. 22B shows the destination set in the IP header in the transfer packet shown in FIG. Address DA
And the source address SA.

When the user specifies the URL of the content data to be acquired for the Web browser application running on the user terminal 101-1, HTTP is used.
The PPP frame 710 including the request message is generated, and the access line 102-1 is transmitted from the user terminal 101-1.
(S1010). In this embodiment, the PP
The destination address of the IP header IP (a) of the P frame 710 is the IP address of the Web server 111.

Upon receiving the PPP frame 710 including the HTTP request message, the LAC 104 sets the destination address of the IP header to the IP address of the Web cache server 113.
Rewriting to address (S1041), IP packet 70
2 is transferred to the Web cache server 113.

The Web cache server 113 uses the LAC
When the IP packet 702 is received from the packet 104, the HT is sent from the data section as in the first embodiment described with reference to FIG.
The TP request message is extracted, and the content data specified by the URL is searched from the cache data (S
1131). When the specified content data is found, an HTTP response message including the content data is generated (S1132), the HTTP response message is included in the data portion, and the I of the requesting user terminal 101-1 is included.
The IP packet 703 having the P address as the destination address is sent to the LAC 104.

Upon receiving the IP packet 703 from the Web cache server 113, the LAC 104 sets the source address of the IP header to the destination address of the packet 710.
That is, the Web on which the user requested the content data
Rewrite to the IP address of the server 111 (S104
2) Convert the PPP frame 712 and transfer it to the access line 102-1.

FIG. 23A shows the second embodiment,
The packet transfer sequence when the content data designated by the HTTP request message does not exist in the Web cache server 113 is shown. FIG. 23B shows
FIG. 24 shows the relationship between the destination address DA and the source address SA set in the IP header of the transfer packet shown in FIG.

Steps S1010 to S1131
Up to this point, it is the same as FIG. As a result of the content search (S1131) in the Web cache server 113, when the content data designated by the URL is not in the cache data, the Web cache is processed by the same procedure as the first embodiment described in FIG. 8A. Server 11
3 transmits the IP packet 705 including the HTTP request message to the Web server 111, and the Web server 1
11 returns an IP packet 709 including an HTTP response message including the designated content data to the Web cache server 113, and the Web cache server 11
3 to the LAC 104, the HTT addressed to the user terminal 101-1
The IP packet 703 including the P response message is transmitted.

Upon receiving the IP packet 703 from the Web cache server 113, the LAC 104 rewrites the source address of the IP header with the IP address of the Web server 111 (S1042), as in (A) of FIG.
The access line 102 is converted to the PPP frame 712.
Transfer to -1. In order to perform the packet transfer described above,
In the gateway device of the second embodiment, the access line compatible protocol processing circuit 81A among the plurality of protocol processing circuits 81A to 81C shown in FIG. 9 includes the HTTP request message management table 850 shown in FIG.

In the PPP frame including the HTTP request message transmitted from the user terminals 101-1 to 101-m, the destination address of the IP header is rewritten to the IP address of the Web cache server 113 in the access line compatible protocol processing circuit 81A. After that, it is transferred to the Web cache server. In addition, the IP packet including the HTTP response message acquired from the Web server by the Web cache server 113 on behalf of the user terminal receives the I packet in the access line compatible protocol processing circuit 81A.
HT in which the source address of the P header is issued by the user terminal
After rewriting to the destination address of the TP request message, it is transferred to the user terminal.

HTTP request message management table 85
0 is the destination I of the HTTP request message issued by the user terminal as the source IP address of the HTTP response message.
This is necessary when rewriting to the P address. For example, as shown in FIG. 24, H received from the user terminal
For each TTP request message, a TCP / UDP source port number 852 and a message destination IP address 853 are stored in association with the PPP connection identifier 851 of the PPP frame of the message.

FIG. 25 shows the flow of packet data inside the LAC of the second embodiment. Here, the same reference numerals as those in FIG. 15 are attached to the packets common to the first embodiment, and the duplicated description will be omitted. Upon receiving the PPP frame from the access line, the access line compatible protocol processing circuit 81A identifies the upper layer protocol of PPP, and if the upper layer protocol is LCP, LCP processing, NC.
In case of P, NCP processing is executed.

When the upper layer protocol is IP, TCP /
Check the destination port number in the UDP header. If the destination port number is, for example, “80”, which is the well-known port number of HTTP, the cache server 113 sends the received packet (HTTP request message).
Destination IP address conversion processing 1509 for forwarding to
Is executed to rewrite the destination address of the IP header with the IP address value of the Web cache server.

The received packet whose address has been translated is the PP
The P connection identifier 1001 is sent to the internal switch 87 in a form in which internal transfer destination information 1010 designating the cache server compatible protocol processing circuit 81B is added. This packet is an IP packet 702 to the cache server 113 via the cache server compatible protocol processing circuit 81B, as in the first embodiment shown in FIG.
Be transferred as. Upper protocols are LCP, NCP,
The received packet other than IP or the IP packet whose destination port number is other than “80” is sent to the internal switch 87 with the internal transfer destination information 1010 designating the IP network compatible protocol processing circuit 81C added.

Upon receiving the IP packet 702, the cache server 113 receives the URL of the HTTP request message.
The content data specified by is searched from the cache data, and the HTT addressed to the user terminal is searched according to the search result.
IP packet 703 including P response message, or W
I including the HTTP request message addressed to the eb server 111
A P packet 705 is generated.

These IP packets are processed by the cache server corresponding protocol processing circuit 81B in accordance with the destination IP address, and the HTTP response message packet having the IP address addressed to the user terminal is transferred to the access line corresponding protocol processing circuit 81A. , Web
The packet for the HTTP request message having the IP address addressed to the server is the IP network compatible protocol processing circuit 81C.
Transferred to. The operations of the cache server compatible protocol processing circuit 81B and the IP network compatible protocol processing circuit 81C are the same as in the first embodiment.

H sent from the cache server 113
The IP packet 703 including the TTP response message is transmitted from the transmission source I by the transmission source IP address conversion processing 1613 executed by the access line compatible protocol processing circuit 81A.
After rewriting the P address to the IP address of the Web server, it is transferred to the requesting user terminal as a PPP packet 712.

FIG. 26 is a flow chart of a received packet processing routine 1500-2 executed by the CPU of the access line protocol processing circuit 81A. The processing steps having the same reference numerals as those in FIG. 16 are common to those in the first embodiment, and therefore their explanations are omitted. When the upper protocol of the received PPP frame is IP (S1504), the upper protocol of IP is determined (S1506). When the upper layer protocol of IP is TCP or UDP, the destination port number of TCP / UDP is identified (S1507). The destination port number is the HTTP well-known port number "8".
If it is "0", the received PPP frame is determined to be Web traffic, and the following processing is performed.

First, a new entry indicating the relationship between the connection identifier of the received PPP frame, the TCP / UDP source port number, and the destination IP address is generated, and H
It is set in the TTP request message management table 850 (S1508). Next, the destination address indicated by the IP header of the received PPP frame is set to the IP of the Web cache server.
The address is rewritten (S1509). At this time, as the destination address is rewritten, the header checksum included in the IP header and the FCS (Frame Chec) of the PPP frame are
k Sequence) is recalculated and each value is updated. Finally, the PPP connection identifier 1001 and the internal transfer destination information 1010 designating the Web cache server compatible protocol processing circuit 81B are added to the received PPP frame and stored in the internal switch transmission buffer 815 (S
1510, the process ends.

When the protocol of the PPP frame is not IP, even if it is IP, the upper protocol is TCP or UDP.
If it is not, or if the destination port number is not “80” even if it is TCP / UDP, it is judged that the received PPP frame is not for Web traffic, and PPP is used.
The connection identifier 1001 and the internal transfer destination information 1010 designating the IP network compatible protocol processing circuit 81C are added and stored in the internal switch transmission buffer 815 (S1540). Through the above processing, the user terminal 101
-1 to 101-m sent to the Web server
The PPP frame including the TP request message can be separated from the PPP connection and transferred to the Web cache server.

FIG. 27 shows a flowchart of a transmission packet processing routine 1600-2 executed by the CPU of the access line network compatible protocol processing circuit 81A. In this routine, transmission P from the internal switch reception buffer 816 is performed.
The PP frame is taken out (S1611), and the PPP connection identifier 1001 attached to the transmission PPP frame
And T in the IP packet included in the transmitted PPP frame
The HTTP request message management table 850 is referred to based on the destination port number extracted from the CP / UDP header, and the PPP connection identifier 851 and the source port number 852 match the PPP connection identifier and the destination port of the transmission PPP frame. The entry is searched (1612).

The value of the destination IP address 853 of the HTTP request message is obtained from the retrieved entry, and the transmission PP
The source IP address of the IP packet included in the P frame is rewritten to the value of the destination IP address (S161).
3). At this time, the header checksum of the IP header and PP
The FCS of the P frame is recalculated and each value is updated. The transmission PPP frame with the rewritten destination IP address is stored in the interface transmission buffer 814 with the PPP connection identifier 1001 added (S1614). The PPP frame stored in the transmission buffer 814 is the access line interface circuit 8
0A, the PPP connection identifier 1001 is removed, and then the packet is sent to the connection line of the destination user terminal.

In the above-mentioned embodiment, by assigning a plurality of IP addresses corresponding to a plurality of ISPs connected to the regional IP network to one Web cache server connected to the LAC, the source user of the HTTP request message is sent. Even if any of the above ISPs is subscribed, the same Web cache server can respond. However, as a modified example of the present invention, a plurality of Web cache servers respectively associated with different ISPs are connected to the LAC, and the LAC transmits the Web traffic IP packet to the Web site corresponding to the joining ISP of the transmission source user. It may be selectively distributed to the cache server.

As is clear from the above embodiments, the gateway device according to the present invention uses the IP over PPP connection.
Packet relay function and We from PPP connection
b Since it has a function of separating IP packets for traffic, it is used as a LAC in an ISP selection type access network system, and by connecting a Web cache server to a gateway device,
An IP packet for Web traffic can be selectively separated from a packet string passing through the AC and transferred to the Web cache server.

[0124]

According to the present invention, the HTTP from the user
In response to the request, the Web cache server can return a response message in place of the Web server that provides the content, and traffic in the regional IP network (Internet access network) connecting the LAC and the ISP network can be reduced, For users, We
b There is an advantage that the response to server access is improved.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of an ISP selection network system to which a gateway device (LAC) of the present invention is applied.

FIG. 2 is a diagram showing a state in which a PPP connection is set up between a user terminal and a LAC in the ISP selection type network system.

FIG. 3 is a diagram showing a state in which a PPP connection is extended to an LNS in the ISP selection network system.

FIG. 4 is a PP for communication between a cache server and a Web server in the ISP selection type network system.
The figure which shows the state in which P connection was set.

FIG. 5 shows a PPP frame format (A) and PP.
The figure which shows the typical identification value (B) set to the protocol field of P frame.

FIG. 6 is a packet transfer sequence (A) when a user terminal acquires Web content data and a destination address DA of an IP header attached to each transfer packet in a conventional ISP selection type network system to which LAC is applied. FIG. 6 is a diagram showing a relationship (B) between a source address SA and a source address SA.

FIG. 7 is a packet transfer sequence (A) when Web content data requested by a user terminal exists in a cache server in an ISP selection type network system in which the gateway device of the first embodiment of the present invention is applied to LAC; The figure which shows the relationship (B) between the destination address DA of the IP header attached to each transfer packet, and the source address SA.

FIG. 8 is a packet transfer sequence (A) when the Web content data requested by the user terminal does not exist in the cache server in the ISP selection type network system in which the gateway device of the first embodiment of the present invention is applied to the LAC. FIG. 3 is a diagram showing a relationship (B) between a destination address DA of an IP header attached to each transfer packet and a source address SA.

FIG. 9 is a block diagram showing the configuration of a gateway device of the present invention applied to LAC.

10 is a protocol processing circuit 81 (81 shown in FIG. 9;
The block diagram which shows the structure of A-81C).

FIG. 11 is a diagram showing a format of packet data transferred between an interface circuit 80 (80A to 80C) and a protocol processing circuit 81 (81A to 81C) in the gateway device of the present invention.

FIG. 12 is a diagram showing a format of packet data transferred between a protocol processing circuit 81 (81A to 81C) protocol processing circuit and an internal switch 87 in the gateway device of the present invention.

FIG. 13 is a protocol processing circuit 81 (81A to 81).
The figure which shows one Example of the user terminal information table 830 with which C) is provided.

FIG. 14 is a protocol processing circuit 81 (81A to 81).
The figure which shows one Example of the ISP information table 840 with which C) is provided.

FIG. 15 is a gateway device (L according to the first embodiment of the present invention;
FIG. 4 is a diagram for explaining the flow of data inside AC).

FIG. 16 is a protocol processing circuit 81A for access line.
10 is a flowchart showing an embodiment of a received packet processing routine 1500 executed in FIG.

FIG. 17 is a protocol processing circuit 81A for access line.
10 is a flow chart showing an embodiment of a transmission packet processing routine 1600 executed in.

FIG. 18: Protocol processing circuit 8 for cache server
3 is a flowchart showing an embodiment of a received packet processing routine 1700 executed in 1B.

FIG. 19: Protocol processing circuit 8 for cache server
3 is a flowchart showing an embodiment of a transmission packet processing routine 1800 executed in 1B.

FIG. 20 is a flowchart showing an embodiment of a received packet processing routine 1900 executed by an IP network compatible protocol processing circuit 81C.

FIG. 21 is a flowchart showing an embodiment of a transmission packet processing routine 2000 executed by an IP network compatible protocol processing circuit 81C.

FIG. 22 is a packet transfer sequence (A) when Web content data requested by a user terminal exists in a cache server in an ISP selection network system in which the gateway device of the second embodiment of the present invention is applied to LAC; Relationship between destination address DA of IP header attached to each transfer packet and source address SA (B)
FIG.

FIG. 23 is a packet transfer sequence (A) when the Web content data requested by the user terminal does not exist in the cache server in the ISP selection type network system in which the gateway device of the second embodiment of the present invention is applied to the LAC. FIG. 3 is a diagram showing a relationship (B) between a destination address DA of an IP header attached to each transfer packet and a source address SA.

FIG. 24 is a diagram showing an embodiment of an HTTP request message management table 850 provided in the access line compatible protocol processing circuit 81A in the second embodiment of the present invention.

FIG. 25 is a gateway device (L of the second embodiment of the present invention;
FIG. 4 is a diagram for explaining the flow of data inside AC).

FIG. 26 is a flowchart showing an example of a received packet processing routine 1500-2 executed by the access line compatible protocol processing circuit 81A in the gateway device of the second embodiment of the present invention.

FIG. 27 is a flowchart showing an example of a transmission packet processing routine 1600-2 executed by the access line compatible protocol processing circuit 81A in the gateway device according to the second embodiment of the present invention.

[Explanation of symbols]

101: user terminal, 102: access line, 103:
PPP connection for user terminal, 104: LAC, 1
05: regional IP network, 106: L2TP connection, 1
97: LNS, 108: ISP network, 109:
Router, 110: Internet, 111: Web server, 112: LAN, 113: Web cache server, 114: RADIUS server, 116: Cache server PPP connection, 120: RADIUS server, 130: DNS server, 80A: Access line interface circuit , 80B: cache server interface circuit, 80C: IP network interface circuit, 81
A: Access line compatible protocol processing circuit, 81B: Cache server compatible protocol processing circuit, 81C: IP
Network compatible protocol processing circuit, 87: internal switch circuit,
88: node control circuit, 90: control terminal, 811: CP
U, 812: memory, 813: interface reception buffer, 814: interface transmission buffer, 815:
Internal switch transmission buffer, 816: Internal switch reception buffer, 817: Inter-CPU communication interface circuit,
820: program storage area, 830: user terminal information management table, 840: ISP information management table, 85
0: HTTP request message management table, 1001:
PPP connection identifier, 1002: PPP header,
1003: Payload part, 1005: IP header, 10
06: HTTP request message, 1007: HTTP response message, 1008: non-HTTP data, 101
0: Internal transfer destination information.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Akinori Honda             216 Totsuka Town, Totsuka Ward, Yokohama City, Kanagawa Prefecture             Ceremony Company Hitachi Ltd. Communication Division F-term (reference) 5K030 GA02 HA08 HC01 HC11 HD03                       HD06

Claims (11)

[Claims] 1. At least one connected to the Internet
L2TP (Layer2 Tunne) connected to an access network accommodating two ISP (Internet Service Provider) networks, and a PPP (Point to Point Protocol) frame received from a user terminal is set on the access network.
LAC (L2TP Access Concentrato) that transfers data to the ISP network via a ling protocol connection.
r) In a gateway device having a function, a cache server interface for packet communication with a cache server that holds some of the content data provided by the Web server connected to the Internet as cache data, and received from a user terminal P including the request message of the Web content in the payload part from the PPP frame sequence
A PPP frame is selected, a request message indicated by the PPP frame is transferred to the cache server via the cache server interface, and a response message received from the cache server via the cache server interface is sent to the user who requested the Web content. A gateway device, comprising: a packet transfer control means for transferring to a terminal in a PPP frame format. 2. The packet transfer control means checks the relationship between a destination address of an IP header included in each PPP frame received from the user terminal and a specific IP address assigned to the cache server, PPP including Web content request message
The gateway device according to claim 1, wherein the gateway device identifies a frame. 3. The user terminal, wherein the packet transfer control means comprises means for storing a plurality of IP addresses assigned to the cache server in association with a plurality of ISP networks accommodated in the access network. Destination address of the IP header included in each PPP frame received from the ISP to which the source user of the PPP frame assigned to the cache server subscribes
The gateway device according to claim 2, wherein the PPP frame including the Web content request message is identified by checking the relationship between the network and the corresponding specific IP address. 4. The packet transfer control means checks the upper protocol of an IP packet included in each PPP frame received from the user terminal, whereby W
The gateway device according to claim 1, wherein a PPP frame including an eb content request message is identified. 5. The packet transfer control means sets the PPs.
TCP (Transmis) of the IP packet included in the P frame
sion control protocol (UDP) or Use Datagram (UDP)
The gateway device according to claim 4, wherein a PPP frame including the Web content request message is identified from a port number in Protocol). 6. The packet transfer control means converts a Web content request message addressed to the Web server received from the cache server via the cache server interface into a PPP frame to convert the L2T.
The gateway device according to any one of claims 1 to 5, further comprising means for sending out to a P connection. 7. An ISP (Inte
rnet service provider) A plurality of LNSs (L2TP Network Servers) for accommodating a network are connected via an access network, and a PPP (Point to Point Protocol) frame received from a user terminal via an access line is transmitted on the access network. Set L2TP (Layer2Tunn)
eling Protocol) Any one of the above L via a connection
In a gateway device having a LAC (L2TP Access Concentrator) function for transferring to an NS, a cache server interface for communicating with a cache server that holds a part of content data provided by the Web server connected to the Internet as cache data An access line interface for communicating with a user terminal via the access line, an access network interface for communicating with the LNS via the access network, and a predetermined protocol process for a packet received from each interface. And a packet transfer control device for selectively transferring to another interface circuit after performing the above, and the packet transfer control device transmits the Web to the payload part from the PPP frame sequence received by the access line interface. Select those containing content request message, which is extracted from the PPP frame W
A gateway device for transferring an eb content request message to a cache server via the cache server interface. 8. The packet transfer control device checks the relationship between a destination address of an IP header included in each PPP frame received by the access line interface and a specific IP address assigned to the cache server. The gateway device according to claim 7, wherein the PPP frame including the Web content request message is identified. 9. The packet transfer control device checks the upper protocol of an IP packet included in each PPP frame received from the access line,
The gateway device according to claim 7, wherein a PPP frame including a Web content request message is identified. 10. The PPP in which the packet transfer control device receives, from the user terminal, a Web content request message addressed to the Web server, which is received from the cache server via the cache server interface.
It is converted into a PPP frame having a PPP header different from the frame, and any L2 set on the access network is converted.
The gateway device according to any one of claims 7 to 9, further comprising means for transmitting to a TP connection. 11. A plurality of ISs connected to the Internet
P (Internet Service Provider) P that is connected to the access network containing the network and received from the user terminal
L2TP (Layer 2 Tunneling Pro) in which a PP (Point to Point Protocol) frame is set on the access network.
LAC (L2TP Access Concentrat) for transferring to any one of the ISP networks corresponding to the ISP to which the user of the user terminal subscribes via a
or) function, in the gateway device, a cache server interface for packet communication with a cache server that holds a part of the content data provided by the Web server connected to the Internet as cache data, and a subscriber ISP. A PPP frame having a payload content request message is selected from a plurality of PPP frames received from different user terminals, and the request message indicated by the PPP frame is sent to the cache server via the cache server interface. A packet that is transferred and transfers the IP packet including the response message received from the cache server via the cache server interface to the user terminal of the Web content request source in the PPP frame format. Gateway device is characterized in that a Tsu-forwarding control means.