Chapter 16: Dynamic Routing Protocols
STANDARD Revision 1.0 C4® CMTS Release 8.3 User Guide
© 2016 ARRIS Enterprises LLC. All Rights Reserved. 473
Dynamic Host Mapping Table
If a router that has been advertising the dynamic name Type-Length-Value (TLV) on the network suddenly stops the
advertisement, the mapping information last received will remain in the dynamic host mapping table for up to one hour.
This allows the network administrator to display the entries in the mapping entry during a time when the network
experiences problems.
Entering the following command, displays the entries in the system-ID-to-router-name mapping table:
show isis hostname
IS-IS Network Topology — Multi-homing
Multi-homing provides the capability to define multiple NSAP addresses, one per area.
Primary Purpose
The primary purpose of IS-IS multi-homing is to merge otherwise disparate, Level 1 areas into one large unified area. The
LSP database thus becomes unified across the individual Level 1 areas.
Note: IS-IS multi-homing is not analogous to the IP concept of sub-interfaces with multiple secondary IP addresses. IP
multi-homing implies that multiple logical subnets can be defined on the same physical link.
Additional Benefit
Multi-homing provides the benefit of not having to take down an IS-IS network during:
NSAP address renumbering.
IS-IS area merging.
IS-IS splitting.
Packet Flow Between IS-IS Systems
IS-IS defines three packet type categories, similar to that defined in OSPF:
Hello packets.
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