Dell Configuration Guide for the S4048–ON System 9.14.2.4

PDF

Advertise IGP Cost as MED for Redistributed Routes

When using multipath connectivity to an external AS, you can advertise the MED value selectively to each peer for redistributed routes. For some peers you can set the internal/IGP cost as the MED while setting others to a constant pre-defined metric as MED value.

Use the set metric-type internal command in a route-map to advertise the IGP cost as the MED to outbound EBGP peers when redistributing routes. The configured set metric value overwrites the default IGP cost.

By using the redistribute command with the route-map command, you can specify whether a peer advertises the standard MED or uses the IGP cost as the MED.

When configuring this functionality:

If the redistribute command does not have metric configured and the BGP peer outbound route-map does have metric-type internal configured, BGP advertises the IGP cost as MED.
If the redistribute command has metric configured (route-map set metric or redistribute route-type metric) and the BGP peer outbound route-map has metric-type internal configured, BGP advertises the metric configured in the redistribute command as MED.
If BGP peer outbound route-map has metric configured, all other metrics are overwritten by this configuration.

NOTE When redistributing static, connected, or OSPF routes, there is no metric option. Simply assign the appropriate route-map to the redistributed route.

The following table lists some examples of these rules.

Table 1. Redistributed Route RulesRedistributed Route Rules
Command Settings	BGP Local Routing Information Base	MED Advertised to Peer WITH route-map metric-type internal	MED Advertised to Peer WITHOUT route-map metric-type internal
redistribute isis (IGP cost = 20)	MED: IGP cost 20	MED = 20	MED = 0
redistribute isis route-map set metric 50	MED: IGP cost 50	MED: 50 MED: 50	MED: 50 MED: 50
redistribute isis metric 100	MED: IGP cost 100	MED: 100	MED: 100