JP2001111620A - Adsl router - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ADSL router that can automatically revise routing information in a direction of improving a utilizing efficiency of an entire network attended with revision of a channel speed so as to enhance the utilizing efficiency of the entire network. SOLUTION: An ADSL interface section 16 has a rate adaptation function that adjusts a transmission rate in response to a line condition such as a distance and a line characteristic, a channel speed monitor section 15 monitors channel sped information of the ADSL interface section 16 and informs a routing protocol processing section 13 about the revised channel speed when finding out a revision of the channel speed information. The routing protocol processing section 13 generates routing information at a cost obtained from the channel speed after the revision correction according to contents of a channel speed and cost corresponding table 14 that is preset when receiving a revision notice of the channel speed from the channel speed monitor section 15 and transmits the routing information to other router.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ADSL router, and more particularly, to an ADSL (Asymmetric Digital).
al Subscriber Line (asymmetric digital subscriber line)
About.

[0002]

2. Description of the Related Art ADSL is one of the typical systems of xDSL, and xDSL mainly uses a subscriber line (copper cable) laid for telephones for several hundred kbps to several Mbp.
s high-speed communication.

[0003] Normal modems use 4 kHz for voice transmission.
Although only the following low frequency band is used, the xDSL modem also uses a high frequency band from about 20 kHz to 1.1 MHz, and the bandwidth is more than 250 times that of a normal modem.

[0004] The xDSL includes the communication speed and transmission distance, and the accommodation station (up) from the user's house and the user's house (down) from the accommodation station.
There are several methods depending on whether the speed to the same is the same (symmetric) or not (asymmetric).
SL (High bit rate DSL), SDS
L (Symmetric DSL), VDSL (Ver
y high bit rate DSL).

ADSL is an asymmetric type in which the upstream / downstream speed is asymmetric, and is a high-speed system in the downstream direction. Therefore, the ADSL is the most suitable technology for the Internet (Web access) having a large downstream communication amount. Expectations are growing as a means of doing so.

[0006] Regarding the above-mentioned xDSL, see "New Information and Communication Quick Understanding Course 34 Chapter 4 Network Equipment and Devices xD
SL Modem "(co-authored by Nobuo Inoue, etc., Nikkei Communication Edition, published by Nikkei BP, April 25, 1999, pp20
8-209). Also, for the spread of ADSL, an ADSL technology called ADSL lite has been proposed.
G of -T. It is recommended as "G.lite" in 992.2 and the like.

[0007]

The above-mentioned conventional ADS
L has the same connection form as the conventional dedicated line connection,
A function specific to ADSL is a Rate Adaptation function that adjusts the transmission rate according to line conditions such as distance and line characteristics. When a certain abnormality occurs in the line, the function is automatically performed. In some cases, the line speed may drop.

In such a case, simply incorporating a conventional router into a network deteriorates the utilization efficiency of the entire network because the network topology is constant despite the change in line speed.

Accordingly, an object of the present invention is to solve the above-mentioned problems, and to automatically change the routing information in a direction to increase the utilization efficiency of the entire network with the change of the line speed. An object of the present invention is to provide an ADSL router capable of improving utilization efficiency.

[0010]

An ADSL router according to the present invention is an ADSL router for controlling a communication path in an asymmetric digital subscriber line, which includes a rate adaptation function for adjusting a transmission rate in accordance with a line condition. Interface means for connecting to an asymmetric digital subscriber line, dynamic routing for executing the communication path control based on renewable routing information, and automatically updating the routing information when the routing information is updated. Routing protocol processing means for notifying each circuit in the network to which the circuit belongs.

That is, the ADSL router of the present invention has means for automatically switching the line speed by the rate adaptation function of ADSL, and means for performing dynamic routing for performing routing based on renewable routing cost information. It is characterized in that the routing cost information corresponding to the line speed preset in those means is automatically notified to other routers, and the efficiency of the entire network is not reduced.

More specifically, the ADSL router according to the present invention, together with a router in a network, includes a DSLA
M (Digital Subscriber Line)
Access Multiplexer) and ISDN
It is connected to the Internet via a network. Within the network, the ADSL router and the router perform dynamic routing for executing communication path control based on updatable routing information, and exchange routing information with each other.

The ADSL router is 6 Mbps downstream (DSLAM → ADSL router direction) and 640 kbp upstream (ADSL router → DSLAM) with the DSLAM.
When the connection is made at a line speed of about s, the fact that connection to the Internet is possible at a small cost is notified to the inside of the network by routing information.

The router inside the network calculates the total cost from the notified cost to the Internet, and if the total cost is smaller through the ADSL router than through the router, each PC inside the network is calculated.
(Personal Computer) sends all packets to the Internet via the ADSL router.

If the line condition between the ADSL router and the DSLAM deteriorates and the line speed of the downstream becomes about 4 Mbps and the upstream becomes about 480 kbps due to the rate adaptation function of the ADSL, the ADSL router sends the downstream 6 MHz.
bps, the upstream is required to cost more than when connected at the line speed of 640 kbps.

In this case, the packet passes through a route where the total cost from the inside of the network to the Internet becomes smaller. If the line condition deteriorates and the line speed of the ADSL router decreases, the packet before the line speed lowers. Packets passing through the same route are reduced, and the efficiency of the entire network is not reduced.

Thus, even when the line speed is changed, it is possible to secure an optimal network topology for each preset line speed by using the routing cost included in the routing information. It does not reduce the utilization efficiency of the entire network.

[0018]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a system configuration including the Internet according to an embodiment of the present invention. Referring to FIG. 1, a system according to an embodiment of the present invention includes a network 7, a DSLAM 8, an ISDN (Int
Egrated Services Digital
The network 7 includes an ADSL router 1 inside the network 7 and the Internet 10.
, Routers 2 and 3 and PCs 4 to 6 are provided.

In this network 7, the ADSL router 1 is connected to the router 3 and the PC 4 via the communication path, the router 2 is connected to the router 3 and the PC 6 via the communication path, and the router 3 is connected via the communication path. And router 2 and P
C4 to C6.

FIGS. 2A and 2B are diagrams showing examples of costs in the system shown in FIG. These FIGS. 1 and 2
The operation of the system for determining a route according to an embodiment of the present invention will be described with reference to FIG.

The network 7 is connected to the Internet 10 via the DSLAM 8 and the ISDN network 9 by ADSL routers 1 and 2 respectively. The ADSL router 1 and the routers 2 and 3 inside the network 7 perform dynamic routing and exchange routing information.

ADSL router 1 goes down to DSLAM 8 (DSLAM 8 → ADSL router 1 direction) 6 Mbp
s, upstream (ADSL router 1 → DSLAM8 direction) 64
When the connection is made at about 0 kbps, the ADSL router 1 notifies the inside of the network 7 with routing information that it can be connected to the Internet 10 at a small cost.

The routers 2 and 3 inside the network 7 calculate the total cost from the notified cost to the Internet 10. If the total cost is smaller through the ADSL router 1 than through the router 2, the network 2 All packets transmitted from each of the PCs 4 to 6 inside 7 to the Internet 10 are transmitted to the Internet 10 via the ADSL router 1. Fig. 2 shows a specific cost example at this time.
(A).

That is, in FIG.
The cost from router 1 to PC 5 is “1”, the cost from ADSL router 1 to PC 6 is “1”, ADSL router 1
The cost from the router to the Internet 10 is “4”, the cost from the router 2 to the PC 4 is “1”, the cost from the router 2 to the PC 5 is “1”, the cost from the router 2 to the Internet 10 is “10”, and the router 3 It is assumed that the cost from the Internet to the Internet 10 is “5”.

In this case, the total cost of PC 4 → ADSL router 1 → Internet 10 is “4”, PC 5 → Router 3
The total cost of → ADSL router 1 → Internet 10 is “5”, and the total cost of PC 6 → Router 2 → Router 3 → ADSL router 1 → Internet 10 is “6”.

The line condition between the ADSL router 1 and the DSLAM 8 deteriorates, and the ADSL Rate Adapta
4Mbps down stream, 480kb up stream by Tion function
In the case of about ps, the ADSL router 1
ps, it is notified as routing information that a higher cost is required than when the connection is performed at 640 kbps. FIG. 2B shows a specific example of the cost.

That is, in FIG.
2A except that the cost from the L router 1 to the Internet 10 is changed to “9”.
→ ADSL router 1 → total cost of Internet 10 is “9”, PC 5 → router 3 → ADSL router 1 → total cost of Internet 10 is “10”, PC 6 → router 2 →
Router 3 → ADSL router 1 → Total cost of Internet 10 is “11”, PC 6 → Router 2 → Internet 10
Becomes 10 and the route from the PC 6 to the Internet 10 is selected from the PC 6 → the router 2 → the Internet 10.

In the above case, the packet passes through a route from the inside of the network 7 to the Internet 10 where the total cost is smaller, and the line condition is deteriorated and the ADSL
When the line speed of the router 1 is reduced, the number of packets passing through the same route as before the line speed is reduced is reduced.
The efficiency of the entire network 7 does not decrease.

FIG. 3 is a block diagram showing a detailed configuration of the ADSL router 1 of FIG. In FIG. 3, the ADSL router 1 includes a routing processing unit 11, a routing protocol processing unit 13, a line speed monitoring unit 15, and an ADSL router.
The interface unit 16 and a LAN (Local Area)
a Network) interface unit 17 and AAL
5 (ATM Adaptation Layer 5)
It comprises a processing unit 18 and a user interface unit 19.

The routing processor 11 is provided with a routing table 12, and the routing protocol processor 13 is provided with a line speed / cost correspondence table 14.

The routing processing unit 11 receives the IP (Integer) input from the AAL5 processing unit 8 via the LAN interface unit 17 and the ADSL interface unit 16 respectively.
(rnet Protocol: network layer protocol of the Internet) A packet routing process is performed, and a process of outputting an IP packet to a routing destination interface is performed. At the time of routing processing, a routing table 12 included in the routing processing unit 11 is referred to.

When a packet having routing information is received, the packet is passed from the routing processing unit 11 to the routing protocol processing unit 13, and the routing protocol processing unit 13 determines the routing table 1 of the routing processing unit 11 according to the contents of the routing information.
Change the contents of 2.

On the other hand, when there is a change in the contents of the routing table 12 or a notification of a change in the line speed from the line speed monitoring unit 15, the routing protocol processing unit 13 preliminarily sets A
From the user terminal (not shown) connected to the DSL router 1, the routing information is created at the cost obtained from the changed line speed according to the contents of the line speed / cost correspondence table 14 set by the user, and the other routers 2, 3 is transmitted to the routing information. The contents of the line speed / cost correspondence table 14 are stored in the user interface unit 19.
From the user.

The ADSL interface section 16 adjusts the transmission rate according to line conditions such as distance and line characteristics, and so on.
n) It has a function, and the line speed monitoring unit 15
It monitors the line speed information in the rate adaptation function of the interface unit 16 and notifies the routing protocol processing unit 13 of the changed line speed when the line speed information is changed.

The line speed monitoring unit 15 can monitor the line speed information by using, for example, a polling process. That is, the line speed monitoring unit 15 periodically monitors the line speed information of the ADSL interface unit 16 at a certain period, and when recognizing a change in the line speed, notifies the routing protocol processing unit 13 of the change in the line speed. .

FIG. 4 is a diagram showing a configuration example of the line speed / cost correspondence table 14 of FIG. In FIG. 4, if the line speed / cost correspondence table 14 is equal to or more than 1024 kbps, “1” is set as the cost and 896 kbps to 896 kbps.
If it is 24 kbps, the cost is “2”, but 768 k
If bps to 896 kbps, cost is "3"
However, if it is 640 kbps to 768 kbps, the cost is “4”. If it is 576 kbps to 640 kbps, the cost is “5”, and the cost is 512 kbps to 576 kb.
If it is ps, the cost is “7”, but 448 kbps ~
If it is 512 kbps, the cost is “9” but 384
If it is kbps to 448 kbps, the cost is “1”.
If “1” is equal to or less than 384 kbps, the cost is “1”.
3 "is written.

FIGS. 5 and 6 are flowcharts showing the processing operation of the ADSL router 1 of FIG. 3 to 6, an ADSL router 1 according to an embodiment of the present invention.
Will be described.

The IP packet received by the LAN interface unit 17 is a MAC (Media Access Co)
ntrol: medium access control) address ARP (A
address Resolution Protco
l) MAC-level reception processing such as registration in the cache is performed (steps S1 and S2 in FIG. 5).

Thereafter, the IP packet received by the LAN interface unit 17 has the destination MAC address of ADSL.
If it is the MAC address of the router 1 (step S5 in FIG. 5)
3), the packet is passed to the routing processing unit 11, and an IP packet receiving process such as checking the contents of the IP header is performed (step S11 in FIG. 5).

If the IP packet received by the LAN interface unit 17 is otherwise (step S3 in FIG. 5), ARP (physical LAN address and logical I
A protocol located between the data link layer and the network layer for associating with the P address) or a discarding process is performed (step S4 in FIG. 5).

On the other hand, the ADSL frame received by the ADSL interface 16
TM (Asynchronous Transfer)
Mode: Asynchronous Transfer Mode) A cell is removed and AAL
5 processing unit 18 (step S5 in FIG. 5),
SAR (Segmentation And Reas)
semly: cell division / assembly) processing is performed and AA
These are combined into an L5 frame (step S6 in FIG. 5).

In the case of IPoA (IP over ATM), RFC (Request for Common) is used.
ts) 1577 (RFC2225), IPoA processing is performed, and the routing processing unit 1
1 (steps S7 and S8 in FIG. 5).

Also, PPPoA (PPP over A)
TM) in the case of PPP (Po) according to RFC2364.
int to Point Protocol: a protocol for making an IP connection over a public line) After assembling into a frame (steps S7 and S9 in FIG. 5), PPP processing is performed, and the packet is passed to the routing processing unit 11 as an IP packet (FIG. 5). Step S10).

The routing processor 11 performs an IP packet receiving process such as checking the contents of the IP header (step S11 in FIG. 5), and the destination IP address of the packet is ADS.
If it is the IP address (or broadcast address) of the L router 1 (step S16 in FIG. 6), the protocol is checked.

If the protocol is a routing protocol (step S1 in FIG. 6)
9) Only when the routing information is changed (FIG. 6)
(Step S21), the contents of the routing table 12 are changed (Step S23 in FIG. 6).

If the routing processor 11 is not a routing protocol (step S19 in FIG. 6), other protocol processing is performed (step S20 in FIG. 6), and if there is no change in the routing information (step S2 in FIG. 6).
1) The packet is discarded (step S22 in FIG. 6).

If the destination IP address is any other (step S16 in FIG. 6), a routing process is performed (step S17 in FIG. 6), and the IP address is determined according to the routing table 12.
The interface to be transmitted is determined from the destination IP address of the packet, and the packet is passed to the determined transmission interface (step S18 in FIG. 6).

When the transmission interface is the LAN interface unit 17, MAC-level transmission processing such as creation of a MAC header is performed (step S24 in FIG. 6), and the packet is actually transmitted from the LAN interface unit 17 (step S6 in FIG. 6). S25).

If the transmission interface is the ADSL interface unit 16, if the AAL5 processing unit 18 is IPoA (step S26 in FIG. 6), an IPoA process for assembling the IP packet into an AAL5 frame is performed (step S27 in FIG. 6). If it is PPPoA (step S26 in FIG. 6), the PPP process and the PPP frame are
The PPPoA process for assembling into the L5 frame is performed (steps S28 and S29 in FIG. 6).

Thereafter, an ATM SAR process for dividing the AAL5 frame into ATM cells is performed (step S6 in FIG. 6).
30), the ADSL interface unit 16 incorporates the ATM cell into the ADSL frame, and the frame is transmitted (step S31 in FIG. 6).

The line speed monitoring unit 15 checks whether or not the ADSL line speed of the ADSL interface unit 16 has been changed (step S12 in FIG. 5). If there is no change, the timer for periodic startup is started, and when the timer times out (step S5 in FIG. 5). S13) Return to step S12 to monitor the line speed again.

When there is a change in the line speed, the line speed monitoring unit 15 starts a timer and notifies the routing protocol processing unit 13 of the changed line speed (step S14 in FIG. 5).

The routing protocol processing unit 13 uses a line speed / cost correspondence table 14 preset by the user from the user interface unit 19 based on the notified line speed.
To find the cost corresponding to the changed line speed,
In order to notify the changed cost as routing information, a routing information packet is created and passed to the routing processing unit 11 (step S15 in FIG. 5).

The routing processor 11 performs a routing process in the same manner as the transmission process of other packets (step S17 in FIG. 6), and transmits a routing information packet (steps S18, S24 to S31 in FIG. 6).

In the conventional dedicated line connection, the line speed is always constant, but when using ADSL, the line speed may change. In such a case, the use efficiency of the entire network may be deteriorated by only the fixed routing information as in the related art.

ADSL router 1 according to one embodiment of the present invention
Since the routing information is automatically changed in a direction to increase the utilization efficiency of the entire network with the change of the line speed, the utilization efficiency of the entire network can be improved as compared with the conventional router.

FIG. 7 shows an ADSL according to another embodiment of the present invention.
FIG. 3 is a block diagram illustrating a detailed configuration of a router. 7, an ADSL router according to another embodiment of the present invention has the same configuration as the ADSL router 1 according to one embodiment of the present invention shown in FIG. Elements have the same reference numerals. The operation of the same component is the same as that of the embodiment of the present invention.

The interrupt generator 20 generates an interrupt when the line speed of the ADSL line is changed. The line speed monitoring unit 15 recognizes that the line speed has been changed by an interrupt from the interrupt generation unit 20. With this as a trigger, the line speed monitoring unit 15 causes the ADSL interface unit 1
6 and notifies the routing protocol processing unit 13 of the changed line speed.

In another embodiment of the present invention, the line speed monitor 15 is activated only when a change occurs in the line speed, so that, in addition to the above effects, the load caused by the constant period activation can be reduced. This has the effect.

[0060]

As described above, according to the present invention, A for performing communication path control in an asymmetric digital subscriber line is provided.
The DSL router includes a rate adaptation function for adjusting a transmission rate in accordance with line conditions and includes interface means for connecting to an asymmetric digital subscriber line and communication path control based on renewable routing information. Routing protocol processing means for performing dynamic routing for updating and notifying the routing information updated when the routing information is updated to each circuit in the network to which the own circuit belongs. The routing information can be changed in a direction to increase the use efficiency of the entire network, and there is an effect that the use efficiency of the entire network can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a system configuration including the Internet according to an embodiment of the present invention.

FIGS. 2A and 2B are diagrams showing examples of costs in the system shown in FIG. 1;

FIG. 3 is a block diagram showing a detailed configuration of the ADSL router of FIG. 1;

FIG. 4 is a diagram showing a configuration example of a line speed / cost correspondence table in FIG. 3;

FIG. 5 is a flowchart showing a processing operation of the ADSL router of FIG. 3;

FIG. 6 is a flowchart showing a processing operation of the ADSL router of FIG. 3;

FIG. 7 is a block diagram illustrating a detailed configuration of an ADSL router according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ADSL router 2, 3 router 4-6 PC 7 Network 8 DSLAM 9 ISDN network 10 Internet 11 Routing processing part 12 Routing table 13 Routing protocol processing part 14 Line speed / cost correspondence table 15 Line speed monitoring part 16 ADSL interface part 17 LAN Interface section 18 AAL5 processing section 19 User interface section 20 Interrupt generation section

Continued on the front page F-term (reference) 5K030 GA03 GA13 GA20 HA08 HC04 HD03 JA11 JL07 KA05 KA14 LB09 LB14 LC11 MA04 MB09 5K034 AA01 DD03 EE11 FF02 HH63 JJ11 KK21 LL01 LL08 MM08 5K035 AA01 BB03 CC03 EE01 BB03 CC03 EE01

Claims (6)

[Claims] An ADSL router for controlling a communication path in an asymmetric digital subscriber line, comprising a rate adaptation function for adjusting a transmission rate in accordance with a line condition, and connecting to the asymmetric digital subscriber line. Performing dynamic routing for executing the communication path control based on the updatable routing information, and notifying the updated routing information to each circuit in the network to which the own circuit belongs when the routing information is updated. An ADSL router comprising routing protocol processing means. 2. A monitoring means for monitoring a line speed of the asymmetric digital subscriber line, wherein the routing protocol processing means updates the routing information based on a monitoring result of the monitoring means and notifies the network of the updated routing information. 2. The ADS according to claim 1, wherein:
L router. 3. The apparatus according to claim 2, wherein said monitoring means periodically monitors line speed information in said rate adaptation function of said interface means to detect a change in line speed of said asymmetric digital subscriber line. The ADSL router according to claim 2, wherein 4. A line speed / cost correspondence table which is settable externally and stores a line speed of said asymmetric digital subscriber line and routing cost information which constitutes said routing information in association with each other. The ADSL router according to claim 2 or 3. 5. The routing protocol processing unit reads routing cost information corresponding to the changed line speed from the line speed / cost correspondence table when the monitoring unit detects a change in the line speed, and performs the routing. 5. The ADSL router according to claim 4, wherein the information is notified to the inside of the network. 6. An interrupting means for constantly monitoring a change in the line speed of the asymmetric digital subscriber line and notifying the monitoring unit of an interrupt when the change in the line speed is detected. An ADSL router according to any one of claims 2 to 5.