Quick Reference Guide

688 PowerConnect B-Series TI24X Configuration Guide

53-1002269-02

Configuring OSPF

The router software can use the route information it learns through OSPF to determine the paths

and costs. Example OSPF network with four equal-cost paths

In the example in Figure , the switch has four paths to R1:

• Device->R3

• Device->R4

• Device->R5

• Device->R6

Normally, the switch will choose the path to the R1 with the lower metric. For example, if R3 metric

is 1400 and R4 metric is 600, the switch will always choose R4.

However, suppose the metric is the same for all four routers in this example. If the costs are the

same, the switch now has four equal-cost paths to R1. To allow the switch to load share among the

equal cost routes, enable IP load sharing. The software supports four equal-cost OSPF paths by

default when you enable load sharing. You can specify from 2 – 6 paths.

NOTE

The switch is not source routing in these examples. The switch is concerned only with the paths to

the next-hop routers, not the entire paths to the destination hosts.

OSPF load sharing is enabled by default when IP load sharing is enabled. To configure IP load

sharing parameters, refer to “Configuring IP load sharing” on page 605.

Configure external route summarization

When the Layer 3 Switch is an OSPF Autonomous System Boundary Router (ASBR), you can

configure it to advertise one external route as an aggregate for all redistributed routes that are

covered by a specified address range.

OSPF Area 0

Device