3Com 4800G Series, Configuration Manual

Page: 412 / 1246

412 C
HAPTER
30: BGP C
ONFIGURATION
[SwitchD] bgp 200
[SwitchD-bgp] peer 194.1.1.2 as-number 200
[SwitchD-bgp] peer 195.1.1.2 as-number 200
[SwitchD-bgp] quit
4 Configure attributes for route 1.0.0.0/8, making Switch D give priority to the route
learned from Switch C.
■
Configure a higher MED value for the route 1.0.0.0/8 advertised from Switch A
to peer 192.1.1.2.
# Define an ACL numbered 2000 to permit route 1.0.0.0/8.
[SwitchA] acl number 2000
[SwitchA-acl-basic-2000] rule permit source 1.0.0.0 0.255.255.255
[SwitchA-acl-basic-2000] quit
# Define two routing policies, apply_med_50, which sets the MED for route
1.0.0.0/8 to 50, and apply_med_100, which sets the MED for route 1.0.0.0/8 to
100.
[SwitchA] route-policy apply_med_50 permit node 10
[SwitchA-route-policy] if-match acl 2000
[SwitchA-route-policy] apply cost 50
[SwitchA-route-policy] quit
[SwitchA] route-policy apply_med_100 permit node 10
[SwitchA-route-policy] if-match acl 2000
[SwitchA-route-policy] apply cost 100
[SwitchA-route-policy] quit
# Apply routing policy apply_med_50 to the route advertised to peer 193.1.1.2
(Switch C), and apply_med_100 to the route advertised to peer 192.1.1.2 (Switch
B).
[SwitchA] bgp 100
[SwitchA-bgp] peer 193.1.1.2 route-policy apply_med_50 export
[SwitchA-bgp] peer 192.1.1.2 route-policy apply_med_100 export
[SwitchA-bgp] quit
# Display the BGP routing table on Switch D.
[SwitchD] display bgp routing-table
Total Number of Routes: 2
BGP Local router ID is 194.1.1.1
Status codes: * - valid, > - best, d - damped,
h - history, i - internal, s - suppressed, S - Stale
Origin : i - IGP, e - EGP, ? - incomplete
Network NextHop MED LocPrf PrefVal Path/Ogn
*>i 1.0.0.0 193.1.1.1 50 100 0 100i
* i 192.1.1.1 100 100 0 100i
You can find route 1.0.0.0/8 is the optimal.
■
Configure different local preferences on Switch B and C for route 1.0.0.0/8,
making Switch D give priority to the route from Switch C.
# Define an ACL numbered 2000 on Router C, permitting route 1.0.0.0/8.