Is-Is Features Supported - 3Com MSR 50 Series Configuration Manual

IS-IS Features Supported

n
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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.
Multiple instances and processes
IS-IS supports multiple instances and processes. Multiple processes allow a
designated 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 designated VPN
instance. Thus, the VPN instance is also associated with interfaces corresponding
to the process.
IS-IS Graceful Restart
For detailed GR information, refer to
After an IS-IS GR Restarter restarts IS-IS, it needs to complete the following two
tasks to synchronize the LSDB with its neighbors.
To obtain effective IS-IS neighbor information without changing adjacencies.
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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.
IS-IS TE
IS-IS Traffic Engineering (TE) creates and maintains the Label Switched Path (LSP).
When creating the Constraint-based Routed LSP (CR LSP), MPLS needs to get the
traffic attribute information of all links in the local area. The Traffic Engineering
information of links is obtained from IS-IS.
For detailed configuration of the IS-IS TE, refer to
page 1345.
Management tag
Management tag carries the management information of the IP address prefixes
and BGP community attribute. It controls the redistribution from other routing
protocols.
LSP fragment extension
IS-IS advertises link state information by flooding LSPs. One LSP carries limited
amount of link state information; therefore, IS-IS fragments LSPs. Each LSP
fragment is uniquely identified by a combination of the System ID, Pseudonode ID
"GR Overview" on page
"MPLS TE Configuration" on
IS-IS Overview 889
1957.