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BGP and BGP4+ Commands
Software Reference Supplement for SwitchBlade® x8112, x908, x900 and x610 Series Switches
3.14 AlliedWare Plus
TM
Operating System - Software Version 5.4.3-2.6 C613-50032-01 REV D
bgp always-compare-med (BGP and BGP4+)
This command enables BGP to compare the Multi Exit Discriminator (MED) for paths from
neighbors in different autonomous systems.
Multi Exit Discriminator (MED) is used in best path selection by BGP. MED is compared
after BGP attributes weight, local preference, AS-path and origin have been compared
and are equal.
By default, MED comparison is done only among routes from the same autonomous
system (AS). Use the bgp always-compare-mode command to allow comparison of MEDs
from different ASs.
A path with a lower MED value is preferred. For example, if the bgp table contains the
following entries, and the bgp always-compare-med command has been issued to
enable this feature:
Route1: as-path 400, med 300
Route2: as-path 200, med 200
Route3: as-path 400, med 250
Route1 is compared to Route2. Route2 is best of the two (lower MED). Next, Route2 is
compared to Route3 and Route2 is chosen best path again (lower MED). If always-
compare-med was disabled, MED is not taken into account when Route1 and Route2 are
compared, because of different ASs and MED is compared for only Route1 and Route3. In
this case, Route3 would be the best path. The selected route is also affected by the bgp
deterministic-med command. See the bgp deterministic-med (BGP and BGP4+)
command on page 3.29 for details.
If this command is used to compare MEDs for all paths, it should be configured on every
BGP router in the AS.
The no variant of this command disallows the comparison.
Syntax bgp always-compare-med
no bgp always-compare-med
Default
By default this feature is disabled.
Mode Router Configuration
Example
Related Commands
bgp bestpath med (BGP and BGP4+)
bgp bestpath as-path ignore (BGP and BGP4+)
bgp bestpath compare-routerid (BGP and BGP4+)
bgp deterministic-med (BGP and BGP4+)
awplus#
configure terminal
awplus(config)#
router bgp 100
awplus(config-router)#
bgp always-compare-med