Protocols And Standards - HPE 5800 Series Configuration Manual

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Operation modes:
The LSP fragment extension feature operates in the following modes:
Mode-1—Applicable to a network where some routers do not support LSP fragment
extension. In this mode, adjacencies are formed between the originating system and virtual
systems, with the link cost from the originating system to each virtual system as 0. Each
virtual system acts as a router connected to the originating system in the network, but the
virtual systems are reachable through the originating system only. The IS-IS routers not
supporting LSP fragment extension can operate properly without modifying the extended
LSP fragments received, but some limitation is imposed on the link state information in the
extended LSP fragments advertised by the virtual systems.
Mode-2—Applicable to a network where all routers support LSP fragment extension. In this
mode, all IS-IS routers know which virtual system belongs to which originating system. No
limitation is imposed on the link state information of the extended LSP fragments advertised
by the virtual systems.
The operation mode of LSP fragment extension is configured based on area and routing level.
Mode-1 allows the routers supporting and not supporting LSP fragment extension to
interoperate with each other, but it restricts the link state information in the extended fragments.
Mode-2 does not restrict the link state information in the extended fragments, and is
recommended for an area where all routers are at the same routing level and support LSP
fragment extension.
Dynamic host name mapping mechanism
The dynamic host name mapping mechanism provides the mappings between the host names and
the system IDs for the IS-IS routers. The dynamic host name information is announced in the
dynamic host name CLV of an LSP.
This mechanism also provides the mapping between a host name and the DIS of a broadcast
network, which is announced in the dynamic host name TLV of a pseudonode LSP.
A host name is easier to remember than a system ID. After enabling this feature on the router, you
can see the host names instead of system IDs by using the display command.
BFD
Bidirectional forwarding detection (BFD) provides a single mechanism to quickly detect any link
failures between IS-IS neighbors to reduce network convergence time.
For more information about BFD, see High Availability Configuration Guide.

Protocols and standards

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ISO 10589, ISO IS-IS Routing Protocol
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ISO 9542, ES-IS Routing Protocol
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ISO 8348/Ad2, Network Services Access Points
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RFC 1195, Use of OSI IS-IS for Routing in TCP/IP and Dual Environments
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RFC 2763, Dynamic Hostname Exchange Mechanism for IS-IS
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RFC 2966, Domain-wide Prefix Distribution with Two-Level IS-IS
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RFC 3277, IS-IS Transient Blackhole Avoidance
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RFC 3358, Optional Checksums in ISIS
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RFC 3373, Three-Way Handshake for IS-IS Point-to-Point Adjacencies
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RFC 3567, Intermediate System to Intermediate System (IS-IS) Cryptographic Authentication
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RFC 3719, Recommendations for Interoperable Networks using IS-IS
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RFC 3786, Extending the Number of IS-IS LSP Fragments Beyond the 256 Limit
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RFC 3787, Recommendations for Interoperable IP Networks using IS-IS
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