3Com Switch 7750 Configuration Guide

362 CHAPTER 36: BGP CONFIGURATION
c
CAUTION:
■ Using routing policy, you can configure the preference for the routes that
match the filtering conditions. As for the unmatched routes, the default
preference is adopted.
■ If other conditions are the same, the route with the lowest MED value is
preferred to be the exterior route of the AS.
■ After BGP load balance is configured, no matter whether the peer
next-hop-local command is executed or not, the local router changes the
next hop IP address to its own IP address before advertising a route to its IBGP
peers/peer group.
Configur
e the
MED
attribute
Configure the default local
MED value
default med
med-value
Optional
By default, the
med-value argument is
0.
Permit to compare the MED
values of the routes coming
from the neighbor routers in
different ASs.
compare-different-as-
med
Optional
By default, the compare
of MED values of the
routes coming from the
neighbor routers in
different ASs is
disabled.
Configure the local address as the next
hop address when a BGP router advertises
a route.
peer group-name
next-hop-local
Required
In some network, to
ensure an IBGP
neighbor locates the
correct next hop, you
can configure the next
hop address of a route
to be the local address
for a BGP router to
advertise route
information to IBGP
peer groups.
Configure the
AS_Path attribute
Configure the
number of local
AS number
occurrences
allowed
peer { group-name |
ip-address }
allow-as-loop
[ number ]
Optional
By default, the number
of local AS number
occurrences allowed is
1.
Assign an AS
number for a peer
group
peer group-name
as-number as-number
Optional
By default, the local AS
number is not assigned
to a peer group.
Configure that the
BGP update
packets only carry
the pubic AS
number in the
AS_Path attribute
when a peer sends
BGP update
packets to BGP
peers.
peer group-name
public-as-only
Optional
By default, a BGP
update packet carries
the private AS number.
Table 299 Configure BGP route attributes
Operation Command Description