Chapter 16: Dynamic Routing Protocols
STANDARD Revision 1.0
C4® CMTS Release 8.3 User Guide
© 2016 ARRIS Enterprises LLC. All Rights Reserved.
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Link-State Database
Each router maintains a link-state database for the OSPFv3 network. This database contains all the collected LSAs, and
includes information on all the routes through the network. OSPFv3 uses this information to calculate the best path to
each destination and populates the routing table with these best paths.
LSAs are removed from the link-state database if no LSA update has been received within a set interval, called the MaxAge.
Routers flood a repeat of the LSA every 30 minutes to prevent accurate link-state information from being aged out.
VRF Requirements
OSPFv3 only runs in the default VRF on the C4/c CMTS.
Stub Area
The amount of external routing information that floods an area can be limited by making it a stub area. A stub area is an
area that does not allow AS External (type 5) LSAs. These LSAs are usually flooded throughout the local AS to propagate
external route information.
Not-So-Stubby Area
A Not-So-Stubby Area (NSSA) is similar to the stub area, except that an NSSA allows you to import autonomous system
external routes within an NSSA using redistribution.
Note: The backbone Area 0 cannot be an NSSA.
Route Summarization
Because OSPFv3 shares all learned routes with every OSPFv3-enabled router, route summarization can be used to reduce
the number of unique routes that are flooded to every OSPFv3-enabled router.