H3C Technologies H3C SR8800 - Manual (Page 165)

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NOTE:
For detailed configuration of the IS-IS TE, see MPLS Configuration Guide.
Management tag
Management tag simplifies routing information management by carrying the management information
of the IP address prefixes (to control route redistribution from other routing protocols) and BGP community
and extended community attributes.
LSP fragment extension
IS-IS advertises link state information by flooding LSPs. Because one LSP carries a limited amount of link
state information, IS-IS fragments LSPs. Each LSP fragment is uniquely identified by a combination of the
System ID, Pseudonode ID (0 for a common LSP or a non-zero value for a Pseudonode LSP), and LSP
Number (LSP fragment number) of the node or pseudo node that generated the LSP. The one-byte LSP
Number field, allowing a maximum of only 256 fragments to be generated by an IS-IS router, limits the
amount of link information that the IS-IS router can advertise.
The LSP fragment extension feature allows an IS-IS router to generate more LSP fragments. Up to 50
additional virtual systems can be configured on the router, and each virtual system is capable of
generating 256 LSP fragments to enable the IS-IS router to generate up to 13056 LSP fragments.
• Terms
{
Originating System
It is the router actually running IS-IS. After LSP fragment extension is enabled, additional virtual
systems can be configured for the router. Originating system is the actual IS-IS process that
originally runs.
{
System ID
System ID of the originating system.
{
Additional System ID
Additional virtual system IDs are configured for the IS-IS router after LSP fragment extension is
enabled. Each additional system ID can generate 256 LSP fragments. Both the additional
system ID and the system ID must be unique in the entire routing domain.
• Virtual System
A virtual system is identified by an additional system ID and generates extended LSP fragments.
• Original LSP
It is the LSP generated by the originating system. The system ID in its LSP ID field is the system ID of
the originating system.
• Extended LSP
Extended LSPs are generated by virtual systems. The system ID in its LSP ID field is the virtual system
ID.
After additional system IDs are configured, an IS-IS router can advertise more link state information
in extended LSP fragments. Each virtual system can be considered a virtual router. An extended
LSP fragment is advertised by a virtual system identified by an additional system ID.
• Operation modes
The LSP fragment extension feature operates in the following modes:
{
Mode-1