JPH1013449A - Routing table updating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To update a routing table in a short time after fault occurrence by monitoring the state change of specific bytes as APS(automatic protection switching) bytes in the line overhead of an optical communication overhead signal and changing a management route of an optical line in case of fault occurrence when the specific bytes change in state. SOLUTION: The APS bytes are positioned as K1 and K2 bytes on the line overhead in the optical communication overhead signal, and transmit information for switching a main signal if a fault occurs to the line. During this period, the fault place is limited, signals in directions to the fault are switched at both the ends of the fault place, and the switched signals are passed through other nodes. Information on the APS bytes is utilized when the routing table is updated to enable high-speed switching. Further, no special monitor packet is needed, so no load is placed on a communication line.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a route (path) when a line failure occurs in an optical synchronous backbone transmission apparatus constructing a management network by section data communication channel (SDCC) communication. The present invention relates to a dynamically selected dynamic routing method.

[0002]

2. Description of the Related Art In an optical synchronous trunk transmission system, NE
(Network Element) (ie, node)
L for the physical layer of operations for communication management
AN (Local Area Network) and SD
Although CC is used, the use of SDCC communication using three bytes D1 to D3 in the section overhead of the optical communication overhead signal is said to be advantageous in terms of security and cost as compared with operation using a LAN,
It is used not only for communication management between stations, but also for communication management between NEs such as nodes and relay devices in the office.

FIG. 4 shows a typical N using SDCC communication.
3 shows an E management network. In this NE management network, a plurality of nodes 11 to 17 are connected in a ring by optical lines. Further, a higher-level operating system or the management device 2 is connected to the node 17. There are redundant routes 31 and 32 on this network.
Exists.

[0004] As described above, the redundant route 3 is provided on the network.
In the case where 1 and 32 exist, a means for determining which route is to be used and automatically switching the route when a failure occurs,
This is called a routing protocol and is implemented in routers and communication terminals.

FIG. 5 shows the relationship between protocol stacks when a routing protocol is implemented using SDCC on an optical synchronous trunk transmission device.

The routing protocol creates a routing table storing communication route information by periodically exchanging information (routing protocol packets) for route determination between terminals and routers. When a failure occurs on a communication path or in a router or a terminal, the monitoring timer of the routing protocol times out to detect the failure, determine an alternative route, and update the routing table. Routing protocols include RIP (Routing Information).
on Protocol: Routing Information Exchange Protocol) or OSPF (Open Shortest Pa
th First Protocol).

However, in a route determination method using a routing protocol, a failure location is detected by a timer timeout, so that the larger the network configuration, the more time is required to find the failure location on the management path. I do. In particular, when a network is constructed by SDCC, if a failure occurs on a transmission path, node management becomes impossible for a period of time (several tens of seconds to several minutes). Specifically, the transmission interval of the RIP packet is 30 seconds, and the time until timeout is 1.5 to 3 minutes.
During this time, it becomes impossible for the operator or the upper OS (operating system) to access the node or the relay device.

As a solution to the problem that a communication disabled state occurs before the rewriting of the routing table as described above, a high-speed route switching method and a router proposed by Masato Tsukakoshi et al. In Japanese Patent Application Laid-Open No. Hei 7-264233 have been proposed. Device. This method aims to solve the problem by periodically sending monitoring packets for mutual monitoring at shorter intervals (1 second) than RIP (3 seconds before updating the routing table). However, simply increasing the number of monitoring packets and shortening the monitoring interval leads to an increase in the load on the communication path and hinders the passage of network management packets. Further, when the monitoring packet is discarded due to an increase in the load on the communication path, there is a risk that the routing table is erroneously rewritten.

[0009]

The first problem of the prior art described above is that when a failure occurs on a node or a communication path, it takes several tens seconds to several minutes to select a management communication path. Meanwhile, the operator cannot manage the node.

[0010] The reason is that the RIP
This is due to the adoption of a dynamic routing protocol. Since the RIP finds a communication path failure due to a timeout, it always requires that time.

The second problem of the above-mentioned prior art is that it is not possible to construct a highly reliable network system simply by shortening the timer interval or increasing the number of packets of the monitoring protocol.

The reason is that the packet interval of the RIP is determined by regulation (RFC1058), so that the interval cannot be changed unnecessarily. Frequent transmission of a monitoring packet using a unique monitoring protocol causes an increase in the load on the communication path due to the monitoring packet itself, and erroneous determination of switching when the monitoring packet is discarded.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to perform a short period of time from the occurrence of a failure on a node or a communication path to the update of a routing table.

A further object of the present invention is to solve the problem by using a method that does not increase the load on the communication path.

[0015]

According to the present invention, the node management of an optical synchronous trunk transmission device in which a plurality of nodes are connected in a ring by an optical line is performed by a section / section in a section overhead of an optical communication overhead signal. A method for updating a routing table applied to a network using a data communication channel (SDCC) and using a routing protocol packet to update a routing table of the nodes constituting the network, the method comprising: Is APS (Automatic Protection) in the line overhead of the optical communication overhead signal.
monitoring the state change of the K1 and K2 bytes acting as n switching bytes and sending out the routing protocol packet used to update the routing table when a state change occurs in the APS byte; There is provided a routing table updating method characterized by changing a management route when a failure occurs in an optical line.

Further, according to the present invention, the node management of the optical synchronous backbone transmission apparatus in which a plurality of nodes are connected in a ring by an optical line is performed by the section data communication channel in the section overhead of the optical communication overhead signal. In a routing table updating method applied to a network performed using (SDCC) and periodically exchanging a routing protocol packet between the nodes in order to update a routing table of the nodes constituting the network, Each of the nodes has an APS (Automatic Pr) in the line overhead of the optical communication overhead signal.
monitoring the change in state of the K1 and K2 bytes acting as protection switching) bytes;
The routing protocol packet used for updating the routing table is transmitted even when a state change occurs in the APS byte, and a management route when a failure occurs in the optical line is changed. A table updating method is obtained.

[0017] Preferably, the routing protocol packet is a RIP (Routing Information Exchange Protocol) packet.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings.

The routing table updating method according to the present invention uses the APS (Au) in the optical communication overhead signal.
tomatic Protection Switch
ing) It is realized by using bytes. APS
The bytes are located as K1 and K2 bytes on the line overhead in the optical communication overhead signal, as shown in FIG. 1, and carry information for switching the main signal when a fault occurs on the line. The time for this information transmission is within 50 msec from the occurrence of the fault, during which the fault location is limited, the signal in the fault direction is switched at both ends of the fault location, and the other nodes pass the switched signal through. By using this APS byte information at the time of updating the routing table, high-speed switching becomes possible. Further, since no special monitoring packet is required, no load is applied to the communication path. Each of the nodes 11 to 17 in the general NE management network using the SDCC communication illustrated in FIG. 4 includes an APS byte monitoring unit that monitors an APS byte (restriction of a failure occurrence location), as described later in detail. The APS byte monitoring unit has a comparing unit that compares the APS byte monitored by the APS byte monitoring unit with the APS byte of the routing table and determines whether the APS byte monitored by the APS byte monitoring unit has changed.

The APS byte is carried on the protection line and terminated at the node. The K1 byte is used for transmitting the switching priority and the node ID of the switching request destination, and the K2 byte is used for transmitting the node ID of the switching request source and the status of the bridge, both of which have a speed of 64 kb / s.

Nodes are classified into the following three types according to their states. If there is no failure on the transmission path, an idle signal is on the APS byte (1: idle state). When a failure occurs and signal deterioration is detected, the detected node creates a switching request and transmits it to the adjacent node in the APS byte. The node that has received this transmits the APS byte one after another in a relay manner (2: through state). When finally transmitted to the request destination, switching is performed (3: switching state). After the switching, the request destination node returns a response (APS response) to the request source node,
The request source is also switched (switching state).

In the present system, the RIP is thrown regardless of the period of 30 seconds until the state is changed by the APS as a trigger. As a result, the routing table can be updated in a short time after the occurrence of the switching. Further, since the subsequent transmission of the RIP is performed normally, the load on the SDCC does not suddenly increase.

FIG. 2 shows the configuration of a node for implementing the present invention.
Shown in Each of the nodes 11 to 17 in the general NE management network using the SDCC communication shown in FIG. 4 monitors the APS code of the APS byte of the line overhead in addition to the conventional routing protocol unit 8, and determines the location of the failure. APS byte monitoring unit 4 and this AP
The APS byte monitored by the S byte monitoring unit 4 is compared with the APS byte of the routing table 9, and a comparison unit 5 that determines whether there is a change in the APS byte monitored by the APS byte monitoring unit 4 is provided. . Each node further obtains a monitoring result in the monitoring unit 6 that monitors the comparison operation in the comparing unit 5 and a monitoring result indicating that the APS byte monitored by the APS byte monitoring unit 4 has changed, and updates the table. And a monitoring data notifying unit 7 for notifying the routing protocol unit 8 of the changed APS byte as monitoring data when the request becomes necessary.

Referring to FIG. 3, the operation of the NE management network to which the present invention is applied will be described.

"Normal state" In the normal state, there is no failure on the transmission line, and an idle signal is carried in the APS byte (see 101 in FIG. 3). Each of the nodes 11 to 17
In the normal state, the R is set to 30
Throw IPs and check the communication status.

When a failure occurs, a line failure occurs on the network operating in the normal state (nodes 15 and 1 in FIG. 3).
6) occurs and the APS byte is transferred,
This is shown at 102 in FIG. 3 (Ring Switch). The switching must be completed within 50 msec after detecting the abnormality. Each node throws a RIP packet 201 to an adjacent node and rewrites the routing table, triggered by a change in the APS byte due to the abnormality detection. At this time, there is no need for the nodes 15 and 16 at both ends of the fault location to throw RIP packets to the switching line side. Also, the RIP may be created assuming that the node connected to the switching side has been disconnected.

[At the time of recovery from a failure] When the failure is recovered and normal operation can be performed, a change to the APS byte is used as a trigger to throw a RIP packet to shift to a shorter route in a short time. It is possible to

In FIG. 3, reference numeral 301 denotes the A
The PS response is shown.

[0029]

The effect of the present invention is that, by realizing a high-speed routing table update at the time of a ring switch due to a line failure, the node can be managed even when a failure occurs.

The reason is that the RIP packets are exchanged using the transmission of the APS byte due to the line failure as a sigma to update the routing table. In addition, at the nodes at both ends of the switching point, the nodes existing on the line side in advance are deleted from the table, thereby realizing quick table updating.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining APS (K1 and K2) bytes of a line overhead in an optical communication overhead signal used by the present invention.

FIG. 2 is a block diagram illustrating a configuration of a node for implementing the present invention.

FIG. 3 is a diagram showing a transmission state of an APS byte according to the present invention.

FIG. 4 is a block diagram of a general NE management network using SDCC communication.

FIG. 5 is a diagram showing a protocol stack when a routing protocol is implemented using SDCC on the optical synchronous trunk transmission device.

[Explanation of symbols]

 11 to 17 node 2 host operating system or management device 31, 32 redundant route 4 APS byte monitoring unit 5 comparison unit 6 monitoring unit 7 monitoring data notification unit 8 routing protocol unit 9 routing table 101 APS byte (normal time) 102 APS byte ( (When a failure occurs) 201 RIP packet 301 APS response

Claims (4)

[Claims] A node management of an optical synchronous trunk transmission device in which a plurality of nodes are connected in a ring by an optical line is performed by using a section data communication channel (SDCC) in a section overhead of an optical communication overhead signal. A routing table update method that uses a routing protocol packet to update a routing table of the node configuring the network, wherein each of the plurality of nodes includes a line overhead of an optical communication overhead signal. APS (Automati
c Protection Switching) Monitors the state changes of the K1 and K2 bytes acting as bytes, and when a state change occurs in the APS byte,
A routing table updating method, comprising: transmitting the routing protocol packet used for updating the routing table; and changing a management route when a failure occurs in the optical line. 2. The method according to claim 1, wherein the routing protocol packet is a RIP (Routing Information Exchange Protocol) packet. 3. A node management of an optical synchronous trunk transmission device in which a plurality of nodes are connected in a ring by optical lines using a section data communication channel (SDCC) in a section overhead of an optical communication overhead signal. A routing table update method for periodically exchanging routing protocol packets between the nodes in order to update a routing table of the nodes configuring the network, wherein each of the plurality of nodes includes: APS (Automati) in the line overhead of the optical communication overhead signal
c Protection Switching) Monitors the state changes of the K1 and K2 bytes acting as bytes and sends out the routing protocol packet used to update the routing table when a state change occurs in the APS byte. And updating a management route when a failure occurs in the optical line. 4. The method according to claim 3, wherein the routing protocol packet is a RIP (Routing Information Exchange Protocol) packet.