Lucent Technologies 6000 - Manual (Page 349)

MAX 6000/3000 Network Configuration Guide 8-1
8 Configuring OSPF Routing
To configure your MAX for Open Shortest Path First (OSPF) routing, you need to determine
the interfaces—LAN or WAN—you wish to support the protocol. To configure OSPF for a
LAN (Ethernet) interface, you use the Ether Options profile. To configure OSPF for a WAN
interface, you use a Connections profile. In addition, you can configure the MAX unit to add
routes from a remote router that does not support OSPF or, in a complex network, configure
the MAX unit as an OSPF internal router.
OSPF overview
OSPF is the next-generation Internet routing protocol designed to overcome the limitations in
Routing Information Protocol (RIP) that have occurred as a result of the growth of the Internet.
RIP is a distance-vector protocol, which uses a hop count to select the shortest route to a desti-
nation network. RIP always uses the lowest hop count, regardless of the speed or reliability of
a link. OSPF is a link-state protocol, which means that OSPF can take into account a variety of
link conditions, such as the reliability or speed of the link, and whether the link is up or down
when determining the best path to a destination network.
With RIP, a destination that requires more than 15 consecutive hops is considered unreachable,
which inhibits the maximum size of a network. OSPF has no hop limitation. You can add as
many routers to a network as you want.
RIP creates a routing table and then propagates it throughout the internet of routers, hop by
hop. With increasing Internet routing traffic, RIP convergence (the time it takes for all routers
to receive information about a topology change) is sometimes slow, resulting in routing loops
and errors.
A RIP router broadcasts its entire routing table every 30 seconds. On a 15-hop network, con-
vergence can be as high as 7.5 minutes. In addition, a large table can require multiple broad-
casts for each update, which consumes a lot of bandwidth. OSPF uses a topological database of
the network and propagates only changes to the database, which results in more efficient pro-
pogation.
OSPF overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1
Configuring OSPF routing in the MAX. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-9