Lsa Type And Flooding - Zte ZXR10 5900E Series User Manual

F 5 OSPF ROUTER TYPES
IGURE
� Internal router: Router's interface is in the same area.
�
Backbone router: Router has at least one interface in Area 0.
� Area Border Router (ABR): Router has at least one interface in
Area 0 and at least one interface in another area.
� Autonomous System Border Router (ASBR): Router connects
an AS that runs OSPF to another AS that runs another protocol,
such as RIP and IGRP.

LSA Type and Flooding

OSPF routers use LSAs to exchange information for the link state
database. LSAs set up an accurate and complete network diagram
routes in a routing table. ZXR10 5900E supports six types of LSAs:
� Type 1 Router LSA
� Type 2 Network LSA
� Type 3 Network Summary LSA
� Type 4 ASBR Summary LSA
� Type 5 AS External LSA
� Type 7 NSSA External LSA
OSPF operations are determined by all routers that share one pub-
lic link state database in a region. Therefore all LSAs need to be
flooded over the region and the processing must be reliable. Each
router sends the LSAs that it receives from a particular area to the
other interfaces in the area. Instead of being packets, LSAs are
contained in Link State Update (LSU) packets. Several LSAs can be
included in one LSU. When a router receives an LSU packet instead
of forwarding it directly, router extracts LSAs from the packet and
puts them into its database. In addition, the router constructs its
own LSU and forwards the modified LSU to neighbors connecting
to it.
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Chapter 3 OSPF Configuration
17