TMS zl Management and Configuration Guide ST.1.1.100226

9-27
Routing
OSPF
OSPF
OSPF is a sophisticated routing protocol designed for large networks.
Read the section below if you are interested in learning more about OSPF and
how it functions on the TMS zl Module. If you are interested only in configuring
OSPF on the module, move directly to “Enable OSPF” on page 9-40.
OSPF Overview
OSPF was designed to cope with several of RIP’s shortcomings. For example,
OSPF provides quicker convergence and more sophisticated methods of
computing best routes. Instead of sending routing table entries, routers send
link state advertisements (LSAs) that allow peers to construct a more com-
prehensive, accurate, moment-to-moment topology of the network.
An LSA advertises the state and cost of each of the router’s connections—to
an OSPF network or to another router. In a network divided into areas, special
LSAs can advertise the state and cost of a connection to the entire range of
networks in an area. Other special LSAs advertise external routes.
OSPF routes are typically more reliable than RIP routes. RIP only takes the
number of hops into account when computing a route’s metric, but OSPF also
considers the relative cost of each link used in the route. OSPF usually
computes the cost of a link relative to that link’s inverse bandwidth.
In addition, RIP networks are limited to 15 hops. OSPF allows networks to
expand beyond this limit.
As it does with RIP, the TMS zl Module can provide security on OSPF. You can
configure a router to require a clear-text or an MD5- encrypted key from a peer
before exchanging LSAs with it.
10.1.7.0/24 10.1.7.1 1 vlan7 connected
172.16.1.0/30 10.1.6.1 7 vlan6 rip
Destination Gateway Metric VLAN Ty p e