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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State Sequence
For a better understanding of this section, see
RFC 2178
http://www.rfc-base.org/txt/rfc-2178.txt
), Section 10.1, Neighbor
States, and Section 10.3, the Neighbor state machine, in order to understand state changes. When the first Hello packet is
received from a new neighbor:
1.
The neighbor is entered into the neighbor table in the init state.
2.
When bidirectional communication is established, the neighbor state becomes two-way as the two interfaces exchange
their link-state databases.
3.
Finally, the neighbor moves into the full state, signifying full adjacency.
If the C4/c CMTS fails to receive any Hello packets from a neighbor for the length of the dead-interval, that adjacency is
broken and considered down.
Adjacency
Not all neighbors establish adjacency. Depending on the network type and designated router establishment, some
neighbors become fully adjacent and share LSAs with all their neighbors, while other neighbors do not.
Adjacency is established using:
Database Description Packets — The Database Description packet includes just the LSA headers from the link-state
database of the neighbor. The local router compares these headers with its own link-state database and determines
which LSAs are new or updated.
Link State Request Packets — The local router sends a Link State Request packet for each LSA for which it needs new
or updated information.
Link State Update Packets — The neighbor responds with a Link State Update packet. This exchange continues until
both routers have the same link-state information.
Router Types
Networks with multiple routers present a unique situation for OSPFv3. If every router floods the network with LSAs, the
same link-state information will be sent from multiple sources.
