Configuring OSPF
December 2005
© Foundry Networks, Inc.
20 - 3
Figure 20.1
OSPF operating in a network
OSPF Point-to-Point Links
OSPF point-to-point links are supported on Gigabit and 10-Gigabit Ethernet interfaces of FESX devices running
software release 02.2.00 or later, and on FSX devices running software release 02.3.01 or later.
One important OSPF process is
Adjacency
. Adjacency occurs when a relationship is formed between
neighboring routers for the purpose of exchanging routing information. Adjacent OSPF neighbor routers go
beyond the simple Hello packet exchange; they exchange database information. In order to minimize the amount
of information exchanged on a particular segment, one of the first steps in creating adjacency is to assign a
Designated Router (DR) and a Backup Designated Router (BDR). The Designated Router ensures that there is a
central point of contact, thereby improving convergence time within a multi-access segment.
In an OSPF point-to-point network, where a direct Layer 3 connection exists between a single pair of OSPF
routers, there is no need for Designated and Backup Designated Routers, as is the case in OSPF multi-access
networks. Without the need for Designated and Backup Designated routers, a point-to-point network establishes
adjacency and converges faster. The neighboring routers become adjacent whenever they can communicate
directly. In contrast, in broadcast and non-broadcast multi-access (NBMA) networks, the Designated Router and
Backup Designated Router become adjacent to all other routers attached to the network.
To configure an OSPF point-to-point link, see “Configuring an OSPF Point-to-Point Link” on page 20-35.
Area Border
Router (ABR)
Autonomous System
Border Router (ASBR)
RIP Router
Area 192.5.1.0
Area 200.5.0.0
Area 195.5.0.0
Area 0.0.0.0 Backbone
Virtual Link
Router A
Router C
e8
Router B
Router E
Router F
Router G
206.5.1.1
208.5.1.1
Area Border
Router (ABR)
Router D
Summary of Contents for FastIron Edge Switch X424
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