3Com S7902E, Configuration Manual

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CLV Code Name PDU Type
132 IP Interface Address IIH, LSP
Code 1 to 10 of CLV are defined in ISO 10589 (code 3 and 5 are not shown in the table), and others are
defined in RFC 1195.
Supported IS-IS Features
Multiple instances and processes
IS-IS supports multiple instances and processes. Multiple processes allow a IS-IS process to work in
concert with a group of interfaces. This means that a router can run multiple IS-IS processes, and each
process corresponds to a unique group of interfaces.
For routers supporting VPN, each IS-IS process is associated with a VPN instance. Thus, the VPN
instance is also associated with interfaces corresponding to the process.
Hot standby
A distributed router supports IS-IS Hot Standby (HSB). The data is copied from the Active Main Board
(AMB) to the Standby Main Board (SMB). Whenever the AMB is down, the SMB can switch to the active
status to run IS-IS.
There are two kinds of IS-IS HSB. One is IS-IS data synchronization backup. After switching from AMB
to SMB, IS-IS can work immediately.
The other HSB is to backup only the configuration information of IS-IS during the switching from AMB to
SMB. After the graceful restart (GR), the IS-IS router will send requests to neighbors to synchronize the
LSDB.
IS-IS Graceful Restart
For detailed GR information, refer to GR Configuration in the High Availability Volume .
After an IS-IS GR Restarter restarts IS-IS, it needs to complete the following two tasks to synchronize
the LSDB with its neighbors.
z
To obtain effective IS-IS neighbor information without changing adjacencies.
z
To obtain the LSDB contents.
After the restart, the GR Restarter will send an OSPF GR signal to its neighbors to keep the adjacencies.
After receiving the responses from neighbors, the GR Restarter can restore the neighbor table.
After reestablishing neighborships, the GR Restarter will synchronize the LSDB and exchange routing
information with all adjacent GR capable neighbors. After that, the GR Restarter will update its own
routing table and forwarding table based on the new routing information and remove the stale routes. In
this way, the IS-IS routing convergence is complete.