C613-50186-01 Rev B
Command Reference for AR2050V
1116
AlliedWare Plus™ Operating System - Version 5.4.7-1.x
BGP
AND
BGP4+ C
OMMANDS
BGP
BESTPATH
MED
bgp bestpath med
Overview
This command controls how the Multi Exit Discriminator (MED) attribute
comparison is performed.
Use the
no
variant of this command to prevent BGP from considering the MED
attribute when comparing paths.
Syntax
bgp bestpath med {[confed] [missing-as-worst]}
Mode
Router Configuration
Usage
The
confed
parameter enables MED comparison among paths learned from
confederation peers. The MED attributes are compared only if there is no external
AS (Autonomous System), where an external AS is one that is not within the
confederation. If there is an external AS in the path, then the MED comparison is
not made.
For example, in the following paths the MED value is not compared with
Path3
since it is not in the confederation. MED is compared for
Path1
and
Path2
only.
•
Path1 = 32000 32004, med=4
•
Path2 = 32001 32004, med=2
•
Path3 = 32003 1, med=1
The effect of the
missing-as-worst
parameter is to treat a missing MED attribute
in a path as having a value of infinity, making the path without a MED value the
least desirable path. If the
missing-as-worst
parameter is not configured, the
missing MED attribute is assigned the value of 0, making the path with the missing
MED attribute the best path.
Examples
awplus#
configure terminal
awplus(config)#
router bgp 100
awplus(config-router)#
bgp bestpath med missing-as-worst
awplus#
configure terminal
awplus(config)#
router bgp 100
awplus(config-router)#
bgp bestpath med confed
awplus#
configure terminal
awplus(config)#
router bgp 100
awplus(config-router)#
bgp bestpath med confed missing-as-worst
Parameter
Description
confed
Compares MED among confederation paths.
missing-as-worst
Treats missing MED as the least preferred one.