Dell S4820T, Configuration Manual

Page: 209 / 1178

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.
Dell Networking OS 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 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 10. Redistributed 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
Border Gateway Protocol IPv4 (BGPv4)
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