D-Link DES-3326SR User Manual page 126

DES-3326SR Layer 3 Fast Ethernet Switch User's Guide
packets
acknowledge
segment and to elect a Designated Router on
multi-access segments.
intervals to be exactly the same between any two
neighbors. If any of these intervals are different,
these routers will not become neighbors on a
particular segment.
• Stub Area Flag − any two routers also have to
have the same stub area flag in their Hello
packets in order to become neighbors.
Adjacencies
Adjacent routers go beyond the simple Hello exchange and
participate in the link-state database exchange process. OSPF
elects one router as the Designated Router (DR) and a second
router as the Backup Designated Router (BDR) on each multi-
access segment (the BDR is a backup in case of a DR failure).
All other routers on the segment will then contact the DR for
link-state database updates and exchanges.
bandwidth required for link-state database updates.
Designated Router Election
The election of the DR and BDR is accomplished using the
Hello protocol. The router with the highest OSPF priority on a
given multi-access segment will be com the DR for that
segment. In case of a tie, the router with the highest Router ID
wins. The default OSPF priority is 1.
indicates a router that can not be elected as the DR.
on each segment
each other's existence
OSPF requires these
This limits the
A priority of zero
114
in order to
on a