BGP Weight per Peer
A different weight can be assigned per address family of a peer. For example, a system can be configured to prefer VPN4 routes from peer A and IPv4 routes from peer B.
If the neighbor weight command is given under a specific address-family mode, the peer weight is set for that specific address family. If the address family is not specifically set, the weight is updated for the default address-family.
Topology
Figure 1-29: BGP Weight Per Peer
R1
#configure terminal | Enter configure mode. |
(config)#router bgp 100 | Assign the ASN value (100) to the router. |
(config-router)#neighbor 1.1.1.2 remote-as 200 | Specify the neighbor's IP address and ASN value. |
(config-router)#address-family ipv4 unicast | Enter address-family ipv4 unicast mode |
(config-router-af)#neighbor 1.1.1.2 activate | Activate the neighbor in address family mode |
(config-router-af)#exit-address-family | Exit address-family ipv4 unicast mode |
(config-router)#commit | Commit the candidate configuration to the running configuration. |
R2
#configure terminal | Enter configure mode. |
(config)#router bgp 200 | Assign the ASN value (200) to the router. |
(config-router)#neighbor 1.1.1.1 remote-as 100 | Specify the neighbor's IP address and ASN value. |
(config-router)# address-family ipv4 unicast | Enter address-family ipv4 unicast mode |
(config-router-af)#neighbor 1.1.1.1 weight 500 | Add a weight of 500 to all the routes coming from the neighbor, 1.1.1.1 (only IPv4 routes). |
(config-router-af)#neighbor 1.1.1.1 activate | Activate the neighbor in address family mode |
(config-router-af)#exit-address-family | Exit address-family ipv4 unicast mode |
(config-router)#commit | Commit the candidate configuration to the running configuration. |
Validation
R1
#show ip bgp summary
BGP router identifier 192.168.56.101, local AS number 100
BGP table version is 1
0 BGP AS-PATH entries
0 BGP community entries
Neighbor V AS MsgRcv MsgSen TblVer InQ OutQ Up/Dow
n State/PfxRcd
1.1.1.2 4 200 6 7 1 0 0 00:02:00
0
Total number of neighbors 1
Total number of Established sessions 1
#show ip bgp neighbors
BGP neighbor is 1.1.1.2, remote AS 200, local AS 100, external link
BGP version 4, local router ID 192.168.52.2, remote router ID 192.168.52.3
BGP state = Established, up for 00:01:17
Last read 00:00:17, hold time is 90, keepalive interval is 30 seconds
Neighbor capabilities:
Route refresh: advertised and received (old and new)
Address family IPv4 Unicast: advertised and received
Received 4 messages, 0 notifications, 0 in queue
Sent 5 messages, 0 notifications, 0 in queue
Route refresh request: received 0, sent 0
Minimum time between advertisement runs is 30 seconds
For address family: IPv4 Unicast
BGP table version 1, neighbor version 1
Index 1, Offset 0, Mask 0x2
Community attribute sent to this neighbor (both)
0 accepted prefixes
0 announced prefixes
Connections established 1; dropped 0
Local host: 1.1.1.1, Local port: 179
Foreign host: 1.1.1.2, Foreign port: 34619
Nexthop: 1.1.1.1
Nexthop global: ::
Nexthop local: ::
BGP connection: non shared network
#show ip route
Codes: K - kernel, C - connected, S - static, R - RIP, B - BGP
O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2,
ia - IS-IS inter area, E - EVPN,
v - vrf leaked
* - candidate default
IP Route Table for VRF "default"
C 1.1.1.0/24 is directly connected, eth1, 00:09:10
C 127.0.0.0/8 is directly connected, lo, 00:15:56
C 192.168.52.0/24 is directly connected, eth0, 00:15:52
Gateway of last resort is not set
R2
#show ip bgp summary
BGP router identifier 192.168.56.102, local AS number 200
BGP table version is 1
0 BGP AS-PATH entries
0 BGP community entries
Neighbor V AS MsgRcv MsgSen TblVer InQ OutQ Up/Dow
n State/PfxRcd
1.1.1.1 4 100 3 3 1 0 0 00:00:34
0
Total number of neighbors 1
Total number of Established sessions 1
#show ip bgp neighbors
BGP neighbor is 1.1.1.1, remote AS 100, local AS 200, external link
BGP version 4, local router ID 192.168.52.3, remote router ID 192.168.52.2
BGP state = Established, up for 00:07:14
Last read 00:00:14, hold time is 90, keepalive interval is 30 seconds
Neighbor capabilities:
Route refresh: advertised and received (old and new)
Address family IPv4 Unicast: advertised and received
Received 16 messages, 0 notifications, 0 in queue
Sent 16 messages, 0 notifications, 0 in queue
Route refresh request: received 0, sent 0
Minimum time between advertisement runs is 30 seconds
For address family: IPv4 Unicast
BGP table version 1, neighbor version 1
Index 1, Offset 0, Mask 0x2
Community attribute sent to this neighbor (both)
Weight500
0 accepted prefixes
0 announced prefixes
Connections established 1; dropped 0
Local host: 1.1.1.2, Local port: 34619
Foreign host: 1.1.1.1, Foreign port: 179
Nexthop: 1.1.1.2
Nexthop global: ::
Nexthop local: ::
BGP connection: non shared network
#show ip route
Codes: K - kernel, C - connected, S - static, R - RIP, B - BGP
O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2,
ia - IS-IS inter area, E - EVPN,
v - vrf leaked
* - candidate default
IP Route Table for VRF "default"
C 1.1.1.0/24 is directly connected, eth1, 00:11:26
C 127.0.0.0/8 is directly connected, lo, 00:21:36
C 192.168.52.0/24 is directly connected, eth0, 00:21:32
Gateway of last resort is not set
Last modified date: 10/16/2023