JP2002247098A - Ppp frame multiplexing device, method and subscriber switchboard - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance line efficiency in the case of connecting a PPP frame multiplexing device with an IP network by using an ISDN line. SOLUTION: This subscriber switchboard is provided with a subscriber storage part (SBM) 13a to store a plurality of subscriber terminals and to perform line concentration of subscriber lines and a service processing part (ASM) 13b to store many subscriber storage parts (SBM) and to realize a service processing function. A distribution switch part 21b identifies a subscriber at a transmitting origin of information including a PPP frame transmitted from the SBM 13a, further adds subscriber identification information and multiplexes the PPP frame. An IP network IF 21f converts the multiplexed PPP frame into PPPoE and outputs it to the IP network.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system for accommodating IP (Internet Protocol) traffic in a digital exchange (hereinafter simply referred to as an exchange) constituting a public communication network. In particular, a PPP (Point-to-Point) in which IP packet data is stored in a data portion.
The present invention relates to a method for multiplexing and transmitting Point Protocol (Frame) frames.

[0002]

2. Description of the Related Art In recent years, for example, NTT Technical Journal 1
September 996, Special Issue: New Node System NS8000
A new local exchange called a multi-location type described in "Series" has been introduced and has begun to provide services. In this technique, as shown in FIG. 10, the functions of the subscriber exchange are a subscriber accommodation function (subscriber accommodation / concentration / multiplexing) and a service processing function (service processing / distribution / relay).
This is not to provide all the local exchanges with these two functions, but to optimally arrange necessary functions. In such a multi-location type local exchange 13 shown in FIG. 10, a line processing unit (ASM) 13 having a function such as a service processing function that can be integrated in one place.
b in a wide area, and a large number of subscriber accommodation units (SB
M) 13a is controlled. Then, the line processing unit (AS)
M) 13b and the subscriber accommodation unit (SBM) 13a are standardized SDH (Synchronous Trans).
A transmission line interface called “ferMode” is used.

FIG. 11 shows a subscriber accommodation unit (SBM) 13a.
2 shows a functional configuration of a line processing unit (ASM) 13b.
The subscriber accommodating unit (SBM) 13a includes an ISDN subscriber circuit (OCU) 20a, a demultiplexing unit (MDX) 20d,
And a concentrator switch section 20b. Line processing unit (AS
M) 13b includes a distribution switch unit 21b, a frame handler (FH) 21j, and an I subscriber line signal processing unit (ISI).
G) 21d, and a processor 21g that controls the line processing module.

[0004] Here, a dial-up IP network connection via a general public communication network using this exchange will be described. ISP (Internet Service)
When used as an access line for connection (ice provider), a dial-up connection method is generally used in the ISDN communication mode using the same circuit switching as that for voice communication. At this time, PPP is used as the layer 2 protocol.
Is used, and as shown in the protocol stack of FIG. 12, a protocol configuration is adopted in which an IP packet is stored in a data portion of a PPP frame.

FIG. 10 shows an example in which an access point to an IP network is located in the same city as a subscriber. First, when a subscriber issues a call setting instruction from a terminal device to the access point, the access point is already set. The terminal adapter (TA) 11-I subscriber signal processing unit (IS
IG) 21d sends and receives a call control packet to perform connection control, and the processor 21g causes the subscriber accommodation unit (SBM) 13
Concentrator switch unit 20b and line processing unit (ASM)
A Bch path is set in the distribution switch unit 21b of 13b,
A layer 1 path is established between the terminal 10 and the PPP termination device 14. In this case, the path setting of the distribution switch unit 21b is turned back in the own station. At this stage, the transmission of the PPP frame becomes possible. First, the LCP (Link) in the PPP is transmitted.
Control Protocol) establishes a layer 2 link, and sets a communication path for passing an upper layer protocol such as IP. At this time, it is also possible to execute user authentication and header compression. Then NCP
(Network Control Protocol
According to 1), an IP address is assigned to the terminal, etc., and a state in which a network layer protocol can be communicated is prepared, and a PPP data communication state is established. PPP termination device 1
In step 4, the PPP frame used for communication between the terminals 10 is terminated, and connection with the IP network is established.

[0006]

The IP network connection via the above-mentioned ISDN exchange uses ISDN circuit switching. Therefore, for example, when the Bch1 channel is used, a bandwidth of 64 kbit / s per subscriber is occupied in the exchange. In addition, a PPP terminating device, which is an access point to the IP network, is installed on the user network interface (UNI) side. Therefore, PP
In order to connect to the P terminating device, it is necessary to secure a band for the number of subscribers. As a result, the efficiency of packet transmission with bursty traffic characteristics is low, and it is also a factor that makes it difficult to reduce network cost.

On the other hand, the PPP terminating device is 64 kbit /
Since it is necessary to prepare ports for s × n subscribers, there is a problem that the amount of hardware increases as the number of subscribers increases.

Japanese Patent Application Laid-Open No. 5-183469 has proposed a method for accommodating IP traffic in a public communication network. This is 64 kb of Bch used for IP network connection.
It / s data is directly framed, frames of multiple subscribers are multiplexed, and I / O
In this system, Bch data is framed irrespective of the presence or absence of an IP packet on the Bch. Therefore, a bandwidth of 64 kbit / s or more per subscriber is required. No consideration is given to efficient accommodation in the switching network.

An object of the present invention is to improve line efficiency when connecting to an IP network using an ISDN network.

[0010]

In order to achieve the above object, the present invention performs the following processing. That is, the PPP transmitted via any of the plurality of subscriber lines
(Point-to-Point Protocol)
Accepts information including frames. By identifying the subscriber line to which the received information has been transmitted, the subscriber from which the information is transmitted is identified. The identification information of the subscriber identified by the identification means is added to the PPP frame included in the information, and the PPP frame is multiplexed.
This processing is preferably performed in the local exchange.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. In the present embodiment, the existing ISDN Dch packet service is used as the route for connecting to the IP network, This is an example in which a PPP frame is stored in 25 packets and packet processing hardware in the local exchange is used for multiplexing the PPP frame. Therefore, the local exchange in this embodiment is
A subscriber receiving a conventional packet service and a subscriber receiving an IP network connection service are accommodated simultaneously.
In this embodiment, DchPVC (Permanen) is used.
t Virtual Circuit: Fixed connection with the other party
Assume that you are using a connection.

FIG. 1 is a diagram showing a network configuration when a local exchange according to a first embodiment of the present invention is used. That is, in the present embodiment, the local exchange 13
Accommodates each subscriber line and is connected to the PPP terminating device 14. The PPP termination device 14 is connected to the IP network.

In each subscriber home 1, a subscriber terminal device (hereinafter referred to as a terminal) 10, a terminal adapter (TA) 1
1, and a network terminating unit (DSU) 12 is installed.

The terminal 10 uses software to perform PPP.
It performs frame processing and TCP / IP processing. That is, terminal 10 generates PPP frame data 720 including IP packet 710 (see FIG. 6). Further, the terminal 10 asynchronously transmits and receives the PPP frame data to and from the terminal adapter (TA) 11 using RS-232C or the like (see FIG. 5).

The terminal adapter (TA) 11 is based on X.
25 (Layer 3 of the OSI reference model) and LAPD
(Link Access Procedure on
the D-channel) protocol (layer 2 of the OSI reference model). For example,
The terminal adapter 11 stores the PPP frame data 72
0 and divide X.0. A process for encapsulation into 25 packets 730 is performed (see FIGS. 5 and 7).

A network termination unit (DSU) 12 terminates the subscriber line of the exchange.

The local exchange 13 has a plurality of subscriber accommodation units (SBMs) 13a and a line processing unit (ASM) 13b. Each subscriber accommodation unit 13a accommodates a plurality of subscriber lines. The line processing unit 13b is connected to the PPP termination device 14. The line processing unit 13 b
The frame data is multiplexed and output to the PPP termination device 14.

Here, the format of input data and output data of the local exchange 13 will be described. FIG.
(A) shows the format of data input from each subscriber's home 1 to the subscriber exchange 13. That is, the input data is IP, layer 4 in layer 5 of the OSI reference model.
In PPP, in layer 3, X. 25, LA for Layer 2
Indicates that PD is used. FIG. 6B shows a format of data output from the local exchange 13 to the PPP terminating device 14. That is, the output data is PPPoE (Point-to-Po
int Protocol over Ethernet
t), Layer 2 uses a frame for Ethernet (registered trademark of Fuji Xerox Co., Ltd.).

FIG. 2 shows a detailed block configuration of the local exchange 13. The subscriber accommodation unit (SBM) 13a is an ISDN subscriber circuit (OCU) 20 for terminating a subscriber line.
a, a demultiplexing unit (MDX) 20d for performing time-division multiplexing and demultiplexing of subscriber data, a concentrator switch unit 20b for concentrating ISDN subscriber lines, and a transmission interface (SD)
H) having 20c.

A path for Dch is set in the concentrator switch section 20b. Also, the PPP data from the subscriber is X. 25 packets 730. The X. 25 packets are additionally LAPD frames 740
Is stored in Details of the LAPD file format are shown in FIG. This LAPD frame 74
0 denotes an ISDN subscriber circuit (OCU) 20a and a demultiplexer (MDX) 20 in a subscriber accommodating unit (SBM) 13a.
d, concentrator switch section 20b, transmission interface (SD
H) The signal is transmitted to the line processing unit (ASM) 13b through 20c. In the demultiplexer (MDX) 20d,
A plurality of subscriber data are time-division multiplexed.

The identification of the subscriber can be performed by identifying the subscriber line. In other words, the subscriber can be identified by knowing from which subscriber line the data is transmitted. Further, when time division multiplexing is performed by the demultiplexing unit (MDX) 20d, it is determined in advance to which time slot number the data transmitted from each subscriber line is set. Therefore, when time-division multiplexing is performed, the subscriber at the transmission source can be specified by the time slot number.

The line processing unit (ASM) 13b includes transmission interfaces 21a and 21h, a distribution switch unit 21b,
An I subscriber line signal processing unit (ISIG) 21d for performing a layer 2 protocol processing of the ISDN subscriber control signal, and a processor 21g for controlling each module in the line processing unit 13
And a frame handler (FH) for multiplexing / demultiplexing Dch / Bch packets and call control signals in layer 2
21c, a plurality of IP network interfaces 21f having an interface function with the IP network side, and a frame sorting unit 21e for outputting a frame to any of the plurality of IP network interfaces 21f.

The distribution switch unit 21b extracts one B channel or D channel arbitrarily determined from the channel structure of the ISDN basic interface or primary group interface multiplexed for each subscriber terminal device. Further, the distribution switch unit 21b separates and edits information of each time slot according to the time slot number of the time division multiplex. The distribution switch unit 21b has a Dch
Path is set.

The frame handler 21 (FH) c performs a process of distributing a control packet and a Dch packet and multiplexing a D channel packet with a PPP frame. Hereinafter, regarding the processing of the frame handler 21 (FH) c,
This will be described with reference to FIG. FIG. 3 shows the frame handler 21
(FH) c receives an input from the distribution switch 21b,
A state is shown in which a frame to be output to the ISIG 21d and a frame to be output to the distribution switch 21b again are sorted.

The time-division multiplexed subscriber data is input to the frame handler (FH) 21c. Each subscriber data represents each time slot as an independent 16
Accepted as kbit / s input channel. A subscriber can be uniquely identified by a time slot number (input channel number) assigned to each time slot as an input channel.

This embodiment shows an example in which 8000 subscribers are accommodated. Frame handler (FH) 21c
Is the received LAPD frame 80 for each input channel.
The SAPI field 801 of 0 (see FIG. 7A) is confirmed. Then, “0” or “6” indicating that the frame is a control signal is set in the SAPI field 801.
If "3" is set, the frame handler 21c
Outputs the frame to the ISIG 21d. SAPI
When “16” indicating that the frame is a packet is set in the field 801, the service form of the subscriber corresponding to the input channel is further confirmed. The confirmation of the service form is performed by referring to a table (not shown) storing service contract information for each subscriber. The following multiplexing is performed on the packet frame.

The frame handler 21c converts the packet frame from the LAPD to the LAPF (Link Access).
Procedure for Frame Mode
(Bearer Service). More specifically, the LAPD frame format 800 shown in FIG. 7A is converted to the LAPF frame format 810 shown in FIG. LAPD to LAP
To convert to F, a header is added. Among the added headers, an address capable of uniquely identifying the subscriber is assigned to the DLCI 813. Note that the LAPD information field 802 is not converted and becomes the LAPF information field 812 as it is.

For example, S of the received LAPD frame
When the API is "16", the input channel number is LAPF
Is converted to a LAPF frame as a DLCI 811.
Further, according to whether the subscriber is a conventional packet subscriber or an IP connection subscriber, the output channel is allocated to channel # 1 for the packet switch or channel # 2 for the IP network. The channel for the IP network of channel # 2 is connected to the frame distribution unit via the distribution switch unit 12. Output channel is 1.5Mbit
/ S band, and a plurality of subscriber data are multiplexed in the 1.5 Mbit / s band. With this frame multiplexing function, when all 8000 subscribers are subscribers for the IP network, multiplexing up to about 80: 1 can be realized (1).
6kbit / s x 8000 subscriptions / 1.5Mbi
t / s ≒ 80).

The multiplexed data is input to the frame distribution unit 21e via the distribution switch unit 21b.

The frame distribution unit 21e receives the LAPF frame, and sends a plurality of IP network interfaces 21
The process of sorting to any of f. This processing will be described with reference to FIG.

In FIG. 4, the frame handler (FH) 21
c to 5 devices (# 0 to # 4), IP network interface 21
The figure illustrates an example in which 10 devices (# 0 to # 9) are provided. 1.5 Mbi in which PPP frame data of a maximum of 8000 subscribers is multiplexed,
Five channels of t / s are input. On the output side,
A 3 Mbit / s channel is set in each IP network interface 21f. Frame sorting unit 21e
Classifies the input DLCI into 10 input channels for each input channel,
The frames are distributed so that the data is output to channels # 0 to # 9 of the IP network interface 21f in ascending order of DLCI.

Further, the frame sorting unit 21e outputs the LA
The DLCI 811 of the PF frame is converted. That is, in each IP network interface 21f, the DLC
Address conversion is performed so that I does not overlap. The provision of the frame sorting unit 21e makes it possible to minimize the amount of hardware of the IP network interface 21f when the number of IP network connection subscribers accommodated by each frame handler (FH) 21c is small.

In the IP network interface 21f, the multiplexed frame is protocol-converted so as to conform to the line protocol on the IP network side, and interfaces with the outside. In the present embodiment, the multiplexed LAPF frame is converted into an Ethernet frame (LAN data). here,
PPPoE defined by RFC2516 is used as a protocol on the IP network side.

The specific conversion procedure will now be described with reference to FIG.
This will be described with reference to FIG. LAPF frame 81
With reference to the DLCI 811 of 0, a PPP frame 720 is extracted for data from the same subscriber. The extraction of the PPP frame 720 is performed according to LAPF, LAPD, X.
25 is terminated. The extracted PPP frame 720 is stored in the PPPoE frame 760.
The PPPoE frame 760 generated here is further stored in a frame 770 for Ethernet.

A session ID is given to the PPPoE frame 760 generated here based on the correspondence table 90 shown in FIG. Table 9 shown in FIG.
0 is the address 91 of the DLCI of the LAPF frame;
Session ID that identifies the subscriber in the PPPoE frame
92 and the MAC address 93 of the PPP terminating device 14 are associated with each other. Therefore, the PPP terminator 14 can identify the link of each subscriber by the session ID. Thus, the local exchange 13 and the PPP terminating device 14 can be connected by a multiplex line.

FIG. 5 summarizes the protocol conversion described above. That is, the P generated by the terminal 10
Based on the PP frame, TA. An LAPD frame including 25 frames is generated. This LA
The PD frame is converted into a LAPF frame in the frame handler (FH) 21c. Furthermore, this L
The APF frame is converted into a PPPoE frame in the IP network interface 21f. This PPPo
The PPP terminating device 14 that has received the E frame terminates the PPP and takes out the IP frame.

In the above embodiment, DchP
Taking VC connection as an example, the case where LAPD is used as a communication protocol between the local exchange 13 and the subscriber home has been described. However, when the number of multiplexed B-channel communications is LAPB (Link Access Processed).
ure Balanced Mode). That is, as in the case of the LAPD, the subscriber terminal 1
The LAP frame transmitted from 0 is converted into a LAPF frame in the frame handler (FH) 21c.

Next, a second embodiment of the present invention will be described.
This will be described with reference to FIG. In the present embodiment, a description will be given focusing on differences from the first embodiment.

In this embodiment, the frame handler (FH) provided in the line processor 13b in the first embodiment
Is provided in the subscriber accommodation unit 13a. Concentrator switch unit 20
b 'extracts one arbitrarily defined B channel or D channel from the channel structure of the ISDN basic interface or the primary rate interface. The frame handler 20e performs the same processing as the frame handler 21c in the first embodiment.

Therefore, in the present embodiment, the channel of the IP connection subscriber is dropped by the concentrator switch unit 20b in the subscriber accommodation unit (SBM) 13a, and the frame handler 2
It multiplexes at 0e and connects to the line processing unit (ASM) 13b. Then, in the line processing unit (ASM) 13b,
A path to the frame distribution unit 21e is set by the distribution switch unit 21b, and is connected to the IP network side via the frame distribution unit 21e and the IP network interface 21f.

As a result, in the present embodiment, after the PPP data is multiplexed in the subscriber accommodating unit (SBM) 13a, it is connected to the line processing unit (ASM) 13b, so that the subscriber accommodating unit (SBM) 13a And line processing unit (ASM) 13
It can be further expected that the number of transmission paths to the channel b is reduced.

As described above, according to the above-described embodiment, in the subscriber exchange for the public communication service,
The distribution switch 21b extracts one predetermined B channel or D channel from the channel structure of the ISDN basic interface or the primary group interface multiplexed for each subscriber terminal device, and outputs the frame handler (F)
H) 21c extracts PPP frame data from the data in the channel from each subscriber terminal device extracted for each subscriber terminal device, and adds an in-device header for identifying the subscriber in the exchange to the PPP frame. Then, by multiplexing the frames and transmitting the multiplexed frame to the outside by the IP network interface 21f, an economical path to the IP network can be obtained.

As a result, it is possible to greatly reduce the resources used in the exchange when accessing the IP network via the subscriber exchange. Further, it is possible to connect the PPP terminating device installed at the access point of the ISP and the exchange with a multiplexed line, and it is possible to suppress an increase in facilities on the PPP terminating device side.

[0044] In addition, the subscriber can be expected to have an economic effect of reducing the charge burden on the IP connection via the public communication network.

[0045]

According to the present invention, according to the present invention, I
When connecting to the P network, the line efficiency can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a network configuration according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a functional configuration of a local exchange according to the first embodiment of the present invention.

FIG. 3 is a diagram illustrating a process of sorting a packet including a control signal and a packet including data in a frame handler.

FIG. 4 is a diagram illustrating a frame distribution process in a frame distribution unit.

FIG. 5 is a diagram showing a protocol stack in a network according to the first embodiment of the present invention.

6A is a frame format of data input to the local exchange, and FIG. 6B is a frame format of data output from the local exchange.

FIG. 7A is a diagram showing a LAPD frame format, and FIG. 7B is a diagram showing a LAPF frame format.

FIG. 8 is a diagram showing an example of the X.100 in the IP network interface unit. 25-P
It is a figure showing a PPoE conversion table.

FIG. 9 is a diagram showing a functional configuration of a local exchange according to the second embodiment of the present invention.

FIG. 10 is a diagram showing an example of a conventional network configuration at the time of IP connection.

FIG. 11 is a diagram showing a functional configuration of a conventional exchange.

FIG. 12 is a diagram showing a protocol stack in a conventional network.

[Explanation of symbols]

10. Terminal (subscriber terminal device) Terminal adapter (TA) 12. 12. Network terminating equipment (DSU) Local exchange 13a. Subscriber accommodation unit (SBM) 13b. Line processing unit (ASM) 14. PPP termination device 20a. OCU (ISDN subscriber circuit) 20b. Concentrator switch units 20c, 21a, 21h. SDH transmission interface 20e. PPP frame multiplex processing unit 21b. Distribution switch unit 21c. PPP frame multiplex processing unit and frame handler 21d. I subscriber line signal processing unit (ISIG) 21e, 40. Frame allocating unit 21f, 42. IP network interface unit 21g. Processor

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Yasuo Kinohin 216 Totsuka-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Inside the Hitachi, Ltd.Communications Division (72) Inventor Makoto Okumura 216 Totsuka-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture (72) Inventor Naohiko Yamamoto 2-3-1 Otemachi, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (72) Inventor Tomoharu Obayashi 2-chome Otemachi, Chiyoda-ku, Tokyo No.3-1 Nippon Telegraph and Telephone Corporation (72) Kazuhiko Hirashima 2-3-1 Otemachi, Chiyoda-ku, Tokyo F-term within Nippon Telegraph and Telephone Corporation 5K028 AA11 CC05 DD07 KK01 KK03 KK32 MM08 RR01 TT01 5K030 GA19 HA08 HC01 JA01 JL08 JT03 KA14 LB19 LE06 5K034 AA04 DD02 DD06 EE11 EE13 FF10 FF13 HH61 JJ11 KK24 MM25 SS02

Claims (6)

[Claims] 1. A PPP (Point-to-Point) transmitted via any one of a plurality of subscriber lines.
(T Protocol) frame, receiving means for receiving information including a frame, identifying means for identifying a subscriber from which the received information is transmitted by identifying a subscriber line to which the received information has been transmitted, and information included in the information. Multiplexing means for adding the identification information of the subscriber identified by the identification means to the PPP frame to be multiplexed, and multiplexing the PPP frame; and output means for outputting the multiplexed PPP frame. Device. 2. The information received by the receiving means is LA.
PD (Link Access Procedure)
on the D-channel) frame or L
APB (Link Access Procedure)
And the multiplexing unit converts the received LAPD frame or LABP frame into a LAPF (Link Acc).
ess Procedure for Frame M
The output means refers to the identification information and converts the PPP frame for each subscriber into a PPPoE (Point-to-Point).
-Point Protocol overEther
2. The PPP frame multiplexing device according to claim 1, wherein the PPP frame multiplexing device converts the output to a net. 3. The multiplexing of the PPP frame is performed according to X. 2
3. The frame multiplexing apparatus according to claim 1, wherein the multiplexing is performed by multiplexing five packets. 4. A subscriber exchange accommodating a plurality of subscriber terminals and having a subscriber accommodating unit for concentrating a subscriber's destination and a line processing unit accommodating the subscriber accommodating unit. The accommodating unit is configured to transmit a Point-to-Point Protocol (PPP) transmitted via any of a plurality of subscriber lines.
col) a receiving unit that receives information including a frame, and an identifying unit that identifies a subscriber line from which the received information has been transmitted, thereby identifying a subscriber from which the information is transmitted. A processing unit that adds identification information of the subscriber identified by the identification unit to the PPP frame included in the information and multiplexes the PPP frame; and outputs the multiplexed PPP frame. Output means. 5. A subscriber exchange accommodating a plurality of subscriber terminals and having a subscriber accommodating unit for concentrating a subscriber's destination and a line processing unit accommodating the subscriber accommodating unit. The accommodating unit is configured to transmit a Point-to-Point Protocol (PPP) transmitted via any of a plurality of subscriber lines.
col) a receiving unit for receiving information including a frame; an identifying unit for identifying a subscriber from which the information is transmitted by identifying a subscriber line to which the received information is transmitted; Multiplexing means for adding the identification information of the subscriber identified by the identification means to the PPP frame and multiplexing the PPP frame, wherein the line processing unit outputs the multiplexed PPP frame Output means. 6. A PPP (Point-to-Point) transmitted via any one of a plurality of subscriber lines.
t Protocol) frame, and identifies the subscriber line from which the received information has been transmitted, thereby identifying the source subscriber of the information. The PPP frame included in the information includes A method of multiplexing a PPP frame, wherein identification information of a subscriber identified by an identification unit is added and a PPP frame is multiplexed.