Reference Guide
Type 7—NSSA-
External LSA
(OSPFv2), Type-7
LSA (OSPFv3)
Routers in an NSSA do not receive external LSAs from ABRs but send external routing information for
redistribution. They use Type 7 LSAs to tell the ABRs about these external routes, which the ABR then translates
to Type 5 external LSAs and oods as normal to the rest of the OSPF network.
Type 8—Link LSA
(OSPFv3)
LSA carries the IPv6 address information of the local links.
Type 9—Link-Local
Opaque LSA
(OSPFv2), Intra-
Area Prex LSA
(OSPFv3)
Link-local opaque LSA as dened by RFC2370 for OSPFv2. Intra-Area-Prex LSA carries the IPv6 prexes of the
router and network links for OSPFv3.
Type 11—Grace LSA
(OSPFv3)
Link-local opaque LSA for OSPFv3 only is sent during a graceful restart by an OSPFv3 router.
The LSA header is common to LSA types. Its size is 20 bytes. One of the elds of the LSA header is the link-state ID. Each router link is
dened as one of four types—type 1, 2, 3, or 4. The LSA includes a link ID eld that identies, by the network number and mask, the object
this link connects to. Depending on the type, the link ID has dierent meanings.
1 Point-to-point connection to another router or neighboring router
2 Connection to a transit network IP address of the DR
3 Connection to a stub network IP network or subnet number
4 Virtual link neighboring router ID
Router priority
Router priority determines the designated router for the network. The default router priority is 1. When two routers are attached to a
network, both attempt to become the designated router. The router with the higher router priority takes precedence. If there is a tie, the
router with the higher router ID takes precedence. A router with a router priority set to zero cannot become the designated router or
backup designated router.
If not assigned, the system selects the router with the highest priority as the DR. The second highest priority is the BDR. Priority rates
from 0 to 255, with 255 as the highest number with the highest priority.
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