Chapter 16: Dynamic Routing Protocols
STANDARD Revision 1.0
C4® CMTS Release 8.3 User Guide
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The ABR has a separate link-state database for each area to which it connects. The ABR sends Inter-Area Prefix (type 3)
LSAs from one connected area to the backbone area.
Autonomous System Boundary Router
OSPFv3 defines one other router type: the Autonomous System Boundary Router (ASBR). This router connects an OSPFv3
area to another Autonomous System (AS).
An AS is a network controlled by a single technical administration entity. OSPFv3 can redistribute its routing information
into another AS or receive redistributed routes from another AS.
Link-State Advertisement
OSPFv3 uses link-state advertisements (LSAs) to build its routing table.
LSA Types
The following tables contains the various LSA Types.
Table 68.
LSA Types
Name
Description
Router LSA
LSA sent by every router. This LSA includes state and cost of all links. Does not include prefix information.
Router LSAa trigger an SPF recalculation. Router LSAs are flooded to the local OSPFv3 area.
Network LSA
LSA sent by the DR. Lists all routers in the multi-access network. This LSA does not include prefix
information. Network LSAs trigger an SPF recalculation.
Inter-Area Prefix
LSA
LSA sent by the area border router to an external area for each destination in local area. This LSA includes
the link cost from area the border router to the local destination.
Inter-Area Router
LSA
LSA sent by the area border router to an external area. This LSA advertises the link cost to the ASBR only.
AS External LSA
LSA generated by the ASBR. This LSA includes the link cost to an external autonomous system destination.
AS External LSAs are flooded throughout the autonomous system.