Flooding Scope; Multiple Instances Per Link; Link-Local Addresses - Avaya ERS 8800 series Configuration Manual

IPv6 routing fundamentals

Flooding scope

LSA flooding scope is generalized in OSPFv3 and coded in the LS type field of the LSA. The
following three flooding scopes are available for LSAs:
• Link-local scope: The LSA is not flooded beyond the local link.
• Area scope: The LSA is flooded in a single OSPF area. Area scope is used in router LSAs,
network LSAs, Inter-Area-Prefix-LSAs, Inter-Area-Router LSAs, and Intra-Area-Prefix-
LSAs.
• AS scope: The LSA is flooded through the routing domain. AS scope is used for AS-
external-LSAs.

Multiple instances per link

OSPFv3 supports multiple OSPF protocol instances on a single link. For example, you can
configure a single link in two or more OSPF areas.
An Instance ID in the OSPF packet header and the OSPF interface structures allow multiple
protocol instances on a single link.

Link-local addresses

IPv6 uses link-local addresses on a single link. Link-local addresses facilitate features such
as neighbor discovery and autoconfiguration. Datagrams with link-local sources are not
forwarded. Instead, routers assign link-local unicast addresses from the IPv6 address range.
OSPF for IPv6 assigns link-local unicast addresses to physical segments attached to a router.
The source for all OSPF packets sent on OSPF physical interfaces is the associated link-
local unicast address. Routers learn link-local addresses for all other nodes on links. The next-
hop information during packet forwarding includes the learned addresses.
For OSPF protocol packets, you must use global scope or site-local IP addresses as the source
for packets.
Link LSA is the only OSPF LSA type that includes link-local addresses. Link-local addresses
must not be advertised in other LSA types.
48 Configuration — IPv6 Routing November 2010