Reference Guide

184 | Border Gateway Protocol IPv4 (BGPv4)
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Dell Networking OS 9.1(1.0) supports configuring 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 in conjunction with the route-map command, you can specify whether
a peer advertises the standard MED or uses the IGP cost as the MED.
Note the following when configuring this functionality:
• If the
redistribute command does not have any metric configured and BGP Peer out-bound 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 out-bound route-map has metric-type internal configured, BGP advertises
the metric configured in the redistribute command as MED.
• If BGP peer out-bound route-map has
metric configured, then all other metrics are overwritten by this.
Table 9-1 gives some examples of these rules.
Ignoring Router-ID for some best-path calculations
Dell Networking OS 9.1(1.0) allows you to avoid unnecessary BGP best-path transitions between external
paths under certain conditions. The
bgp bestpath router-id ignore command reduces network disruption
caused by routing and forwarding plane changes and allows for faster convergence.
Note: When redistributing static, connected or OSPF routes, there is no metric option. Simply assign the
appropriate route-map to the redistributed route.
Table 9-1. Example MED advertisement
Command Settings
BGP Local Routing
Information Base MED Advertised to Peer
WITH route-map metric-type
internal
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
redistribute isis metric 100 MED: IGP cost 100 MED: 100 MED: 100