Enable Peer Groups
A BGP speaker might have the same update policies for a set of its peers. This is very useful if you have to change the update policies for all of the peers: Changing individual routers for separate policies can be very time-consuming, thus, peer groups play an important role in creating and assigning policies to a group of routers.
The peer group can be created dynamically or statically.
For dynamic peer groups all configuration can be done at group level only.
The static peer group configuration falls into two categories:
• Attributes that can be configured only at group level. Attempt to configure at member peer level will return error.
• Attributes that allow member peer level configuration. The member peer configuration has precedence.
Category A: Neighbor configuration allowed only at peer-group level
The outbound update impacting configurations of peer group will replace peer member configurations of same attributes when a peer becomes member of peer group. Outbound attribute modifications to group members are not allowed.
Following are the commands which are allowed at peer-group level.
• neighbor WORD activate - neighbor activate
• neighbor WORD as-origination-interval <1-65535> - neighbor as-origination-interval
• neighbor WORD attribute-unchanged ({as-path|next-hop|med}|) - neighbor attribute-unchanged
• neighbor WORD fall-over bfd - neighbor extended-optional-param
• neighbor WORD fall-over bfd multihop - neighbor extended-optional-param
• neighbor WORD next-hop-self - neighbor next-hop-self
• neighbor WORD remove-private-AS - neighbor remove-private-AS
• neighbor WORD route-reflector-client - neighbor route-reflector-client
• neighbor WORD route-server-client - neighbor route-server-client
• neighbor WORD send-community - neighbor send-community
• neighbor WORD distribute-list WORD out - neighbor distribute-list
• neighbor WORD dont-capability-negotiate - neighbor dont-capability-negotiate
• neighbor WORD capability orf prefix-list (both|receive|send) - neighbor capability orf prefix-list
• neighbor WORD filter-list WORD out - neighbor filter-list
• neighbor WORD prefix-list WORD out - neighbor prefix-list
• neighbor WORD route-map WORD out - neighbor route-map
• neighbor WORD advertisement-interval <1-65535> - neighbor advertisement-interval
• neighbor WORD disallow-infinite-holdtime - neighbor disallow-infinite-holdtime
• neighbor WORD local-as <1-4294967295> - neighbor local-as
Category: Neighbor configuration allowed at peer-group member level; precedence based
For the below configuration, member level configurations will take precedence over peer group configuration.
Following are the commands which are allowed at member level also.
• neighbor WORD authentication-key WORD - neighbor authentication-key
• neighbor WORD remote-as <1-4294967295> - neighbor remote-as
• neighbor WORD allowas-in <1-10> - neighbor allowas-in
• neighbor WORD description WORD - neighbor description
• neighbor WORD distribute-list WORD In - neighbor distribute-list
• neighbor WORD ebgp-multihop - neighbor ebgp-multihop
• neighbor WORD ebgp-multihop <1-255> - neighbor ebgp-multihop
• neighbor WORD maximum-prefix <1-4294967295> - neighbor maximum-prefix
• neighbor WORD update-source WORD - neighbor update-source
• neighbor WORD weight <0-65535> - neighbor weight
• neighbor WORD shutdown - neighbor shutdown
• neighbor WORD strict-capability-match - neighbor strict-capability-match
• neighbor WORD route-map WORD in - neighbor route-map
• neighbor WORD prefix-list WORD in - neighbor prefix-list
• neighbor WORD passive - neighbor passive
• neighbor WORD override-capability - neighbor override-capability
• neighbor WORD filter-list WORD in - neighbor filter-list
• neighbor WORD enforce-multihop - neighbor enforce-multihop
• neighbor WORD collide-established - neighbor collide-established
BGP Peer Groups for Address-Family IPv4 Unicast
In the following scenario, R1, R2, and R3 belong to the same peer group ABC. R1, R2 and R3 are in AS 200 and R1 is the route reflector.R4 and R1 are eBGP peers. R4 is in AS 100.
Topology
Figure 1-17: BGP Peer Groups with IPv4 Unicast Members
R1
#configure terminal | Enter configure mode. |
(config)#router bgp 200 | Define the routing process. The number 200 specifies the AS number of R2. |
(config-router)#neighbor ABC peer-group | Configuring ABC peer-group |
(config-router)#neighbor ABC remote-as 200 | Assign options to the peer group named ABC. |
(config-router)#neighbor 2.2.2.2 peer-group ABC | Define neighbor 2.2.2.2 (R2) as a peer group member. |
(config-router)#neighbor 3.3.3.3 peer-group ABC | Define neighbor 3.3.3.3 (R3) as a peer group member. |
(config-router)#neighbor 4.4.4.4 remote-as 100 | Define neighbor 4.4.4.4 (R4) is the IP address of R4 and 100 is the AS number. |
(config-router)#address-family ipv4 unicast | Enter address-family ipv4 unicast mode |
(config-router-af)# neighbor ABC activate | Activate neighbor under address family mode |
(config-router-af)# neighbor 4.4.4.4 activate | Activate neighbor under address family mode |
(config-router-af)# neighbor ABC route-reflector-client | Configure the peer-group ABC to be route-reflector-client |
(config-router-af)#network 1.1.1.1/32 | Advertise the network 1.1.1.1/32 |
(config-router-af)#network 11.11.11.11/32 | Advertise the network 11.11.11.11/32 |
(config-router-af)#exit-address-family | Exit address family mode |
(config-router)#commit | Commit the candidate configuration to the running configuration. |
R2
#configure terminal | Enter configure mode. |
(config)#router bgp 200 | Define the routing process. The number 200 specifies the AS number of R2. |
(config-router)#neighbor 2.2.2.1 remote-as 200 | Create a TCP connection with neighbor 2.2.2.1 of AS 200. |
(config-router)#address-family ipv4 unicast | Enter address-family ipv4 unicast mode |
(config-router-af)# neighbor 2.2.2.1 activate | Activate neighbor under address family mode |
(config-router-af)#exit-address-family | Exit address family mode |
(config-router)#commit | Commit the candidate configuration to the running configuration. |
R3
#configure terminal | Enter configure mode. |
(config)#router bgp 200 | Define the routing process. The number 200 specifies the AS number of R3. |
(config-router)#neighbor 3.3.3.1 remote-as 200 | Create a TCP connection with neighbor 3.3.3.1 of AS 200. |
(config-router)#address-family ipv4 unicast | Enter address-family ipv4 unicast mode |
(config-router-af)# neighbor 3.3.3.1 activate | Activate neighbor under address family mode |
(config-router-af)#exit-address-family | Exit address family mode |
(config-router)#commit | Commit the candidate configuration to the running configuration. |
R4
#configure terminal | Enter configure mode. |
(config)#router bgp 100 | Define the routing process. The number 100 specifies the AS number of R4. |
(config-router)#neighbor 4.4.4.1 remote-as 200 | Create a TCP connection with neighbor 4.4.4.1 of AS 200. |
(config-router)#address-family ipv4 unicast | Enter address-family ipv4 unicast mode |
(config-router-af)# neighbor 4.4.4.1 activate | Activate neighbor under address family mode |
(config-router-af)#exit-address-family | Exit address family mode |
(config-router)#commit | Commit the candidate configuration to the running configuration. |
Validation
R1
R1#show ip bgp neighbors
BGP neighbor is 2.2.2.2, remote AS 200, local AS 200, internal link
Member of peer-group ABC for session parameters
BGP version 4, local router ID 192.168.52.2, remote router ID 10.12.7.155
BGP state = Established, up for 00:04:55
Last read 00:04:55, 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 11 messages, 0 notifications, 0 in queue
Sent 11 messages, 0 notifications, 0 in queue
Route refresh request: received 0, sent 0
Minimum time between advertisement runs is 5 seconds
For address family: IPv4 Unicast
BGP table version 1, neighbor version 1
Index 1, Offset 0, Mask 0x2
ABC peer-group member
Route-Reflector Client
Community attribute sent to this neighbor (both)
0 accepted prefixes
2 announced prefixes
Connections established 1; dropped 0
Local host: 2.2.2.1, Local port: 33865
Foreign host: 2.2.2.2, Foreign port: 179
Nexthop: 2.2.2.1
Nexthop global: 1111::1
Nexthop local: fe80::a00:27ff:fecc:47a6
BGP connection: non shared network
BGP neighbor is 3.3.3.3, remote AS 200, local AS 200, internal link
Member of peer-group ABC for session parameters
BGP version 4, local router ID 192.168.52.2, remote router ID 10.12.7.153
BGP state = Established, up for 00:04:55
Last read 00:04:55, 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 11 messages, 0 notifications, 0 in queue
Sent 11 messages, 0 notifications, 0 in queue
Route refresh request: received 0, sent 0
Minimum time between advertisement runs is 5 seconds
For address family: IPv4 Unicast
BGP table version 1, neighbor version 1
Index 2, Offset 0, Mask 0x4
ABC peer-group member
Route-Reflector Client
Community attribute sent to this neighbor (both)
0 accepted prefixes
2 announced prefixes
Connections established 1; dropped 0
Local host: 3.3.3.1, Local port: 44280
Foreign host: 3.3.3.3, Foreign port: 179
Nexthop: 3.3.3.1
Nexthop global: fe80::a00:27ff:fe85:25d4
Nexthop local: ::
BGP connection: non shared network
BGP neighbor is 4.4.4.4, remote AS 100, local AS 200, external link
BGP version 4, remote router ID 10.12.7.120
BGP state = Established, up for 00:04:55
Last read 00:04:55, 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 11 messages, 0 notifications, 0 in queue
Sent 11 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 3, Offset 0, Mask 0x8
Community attribute sent to this neighbor (both)
0 accepted prefixes
2 announced prefixes
Connections established 1; dropped 0
Local host: 4.4.4.1, Local port: 55493
Foreign host: 4.4.4.4, Foreign port: 179 Nexthop: 4.4.4.1
Nexthop global: fe80::a00:27ff:fe7e:674a
Nexthop local: ::
BGP connection: non shared network
R1#show ip bgp summary
BGP router identifier 192.168.52.2, 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/ Down State/PfxRcd
2.2.2.2 4 200 12 12 1 0 0 00:05:02 0
3.3.3.3 4 200 12 12 1 0 0 00:05:02 0
4.4.4.4 4 100 12 12 1 0 0 00:05:02 0
Total number of neighbors 3
Total number of Established sessions 3
R2
R2#show ip bgp
BGP table version is 4, local router ID is 10.12.65.123
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
l - labeled, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*>i 1.1.1.1/32 2.2.2.1 0 100 0 i
*>i 11.11.11.11/32 2.2.2.1 0 100 0 i
Total number of prefixes 2
R2#
R3
R3#show ip bgp
BGP table version is 8, local router ID is 10.12.65.121
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
l - labeled, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*>i 1.1.1.1/32 3.3.3.1 0 100 0 i
*>i 11.11.11.11/32 3.3.3.1 0 100 0 i
Total number of prefixes 2
R3#
Peer-group can have either iBGP or eBGP peers but not both.
Validation
The configuration above fails with an appropriate error:
R1(config)#router bgp 200
R1(config-router)#neighbor 4.4.4.4 peer-group ABC
%% Peer with AS 100 cannot be in this peer-group, members must be all internal or all external
R1(config-router)#
Peer group members inherit the properties of Outbound Policies configured for Peer-group.
R1
#configure terminal | Enter configure mode. |
(config)# ip access-list permit-1 | Configure access-list to permit 1.1.1.1/32 |
(config-ip-acl)# permit any 1.1.1.1/32 any | Configure a permit statement in the acl to permit 1.1.1.1/32 |
(config-ip-acl)#exit | Exit ip access-list mode |
(config)# route-map permit-only-1 | Configure route-map |
(config-route-map)# match ip address permit-1 | Configure a match statement in the route-map to match the access-list permit-1 |
(config-route-map)#set local-preference 250 | Set local preference as 250 |
(config-route-map)#exit | Exit route-map mode |
(config)#router bgp 200 | Define the routing process. The number 200 specifies the AS number of R1. |
(config-router)# address-family ipv4 unicast | Enter address-family ipv4 unicast mode |
(config-router-af)# neighbor ABC route-map permit-only-1 out | Configure the peer-group ABC with route-map in the outbound direction |
(config-router-af)#exit | Exit router BGP mode |
(config-router)#exit | Exit router mode. |
(config)#commit | Commit the candidate configuration to the running configuration. |
(config)# exit | Exit configure terminal mode |
#clear ip bgp peer-group ABC soft out | Do outbound soft reset for the peer-group ABC for the policy to take affect for the peer-group members |
Validation
R1
R1#show bgp neighbors 2.2.2.2
BGP neighbor is 2.2.2.2, remote AS 200, local AS 200, internal link
Member of peer-group ABC for session parameters
BGP version 4, local router ID 10.12.65.126, remote router ID 10.12.65.123
BGP state = Established, up for 00:07:01
Last read 00:00:15, 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 20 messages, 0 notifications, 0 in queue
Sent 28 messages, 1 notifications, 0 in queue
Route refresh request: received 0, sent 0
Minimum time between advertisement runs is 5 seconds
For address family: IPv4 Unicast
BGP table version 1, neighbor version 1
Index 1, Offset 0, Mask 0x2
ABC peer-group member
Route-Reflector Client
Community attribute sent to this neighbor (both)
Outbound path policy configured
Route map for outgoing advertisements is *permit-only-1
0 accepted prefixes
1 announced prefixes
Connections established 2; dropped 1
Local host: 2.2.2.1, Local port: 179
Foreign host: 2.2.2.2, Foreign port: 42657
Nexthop: 2.2.2.1
Nexthop global: ::
Nexthop local: ::
BGP connection: non shared network
Last Reset: 00:08:39, due to Hold Timer Expired (Notification sent)
Notification Error Message: (Hold Timer Expired/No sub-error code)
R1#show bgp neighbors 3.3.3.3
BGP neighbor is 3.3.3.3, remote AS 200, local AS 200, internal link
Member of peer-group ABC for session parameters
BGP version 4, local router ID 10.12.65.126, remote router ID 10.12.65.121
BGP state = Established, up for 00:11:46
Last read 00:00:18, 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 29 messages, 0 notifications, 0 in queue
Sent 32 messages, 0 notifications, 0 in queue
Route refresh request: received 0, sent 0
Minimum time between advertisement runs is 5 seconds
For address family: IPv4 Unicast
BGP table version 1, neighbor version 1
Index 2, Offset 0, Mask 0x4
ABC peer-group member
Route-Reflector Client
Community attribute sent to this neighbor (both)
Outbound path policy configured
Route map for outgoing advertisements is *permit-only-1
0 accepted prefixes
1 announced prefixes
Connections established 1; dropped 0
Local host: 3.3.3.1, Local port: 179
Foreign host: 3.3.3.3, Foreign port: 48008
Nexthop: 3.3.3.1
Nexthop global: ::
Nexthop local: ::
BGP connection: non shared network
R2
R2#show ip bgp
BGP table version is 3, local router ID is 10.12.65.123
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
l - labeled, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*>i 1.1.1.1/32 2.2.2.1 0 250 0 i
Total number of prefixes 1
R3
R3#show ip bgp
BGP table version is 7, local router ID is 10.12.65.121
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
l - labeled, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*>i 1.1.1.1/32 3.3.3.1 0 250 0 i
Total number of prefixes 1
Peer-group-members cannot be configured with Outbound Policies.
Validation
The above configuration fails with an appropriate error:
R1(config)#router bgp 200
R1(config)#address-family ipv4 unicast
R1(config-router-af)#neighbor 2.2.2.2 route-map permit-only-11 out
%% Invalid command for a peer-group member
Peer-group-members inherit the properties of Inbound Policies configured for Peer-group.
R2
#configure terminal | Enter configure mode. |
(config)# interface lo | Enter interface mode for Loopback interface |
(config-if)#ip address 100.1.1.1/24 secondary | Configure IP address for Loopback interaface |
(config-if)#interface eth3 | Enter interface mode for interface eth3 |
(config-if)#ip address 22.1.1.1/24 | Configure IP address for interface eth3 |
(config-if)#exit | Exit interface mode |
(config)#router bgp 200 | Enter router bgp mode |
(config-router)#address-family ipv4 unicast | Enter address-family ipv4 unicast mode |
(config-router-af)#network 22.1.1.0/24 | Advertise the network of eth3 in BGP |
(config-router-af)#network 100.1.1.0/24 | Advertise the network of Loopback in BGP |
(config-router-af)#exit-address-family | Exit address family mode. |
(config-router)#commit | Commit the candidate configuration to the running configuration. |
R3
#configure terminal | Enter configure mode. |
(config)# interface lo | Enter interface mode for Loopback interface |
(config-if)#ip address 100.1.1.2/24 secondary | Configure IP address for Loopback interaface |
(config-if)#interface eth3 | Enter interface mode for interface eth3 |
(config-if)#ip address 22.1.1.2/24 | Configure IP address for interface eth3 |
(config-if)#exit | Exit interface mode |
(config)#router bgp 200 | Enter router bgp mode |
(config-router)#address-family ipv4 unicast | Enter address-family ipv4 unicast mode |
(config-router-af)#network 22.1.1.0/24 | Advertise the network of eth3 in BGP |
(config-router-af)#network 100.1.1.0/24 | Advertise the network of Loopback in BGP |
(config-router-af)#exit-address-family | Exit address family mode. |
(config-router)#commit | Commit the candidate configuration to the running configuration. |
R1
#configure terminal | Enter configure mode. |
(config)#ip access-list permit-22 | Configure access-list to permit 22.1.1.0/24 |
(config-ip-acl)# permit any 22.1.1.0/24 any | Configure a permit statement to permit 22.1.1.0/24 |
(config-ip-acl)#exit | Exit ip access-list mode |
(config)#route-map permit-only-22 | Configure route-map |
(config-route-map)#match ip address permit- 22 | Configure match statement in route-map to match the access- list permit-22 |
(config-route-map)#exit | Exit route-map mode |
(config)#router bgp 200 | Enter BGP router mode |
(config)# address-family ipv4 unicast | Enter address-family ipv4 unicast mode |
(config-router-af)# neighbor ABC activate | Activate peer-group in the address family |
(config-router-af)#neighbor ABC route-map permit-only-22 in | Configure the peer-group ABC with route-map in the inbound direction |
(config-router)#exit | Exit router bgp mode |
(config)#commit | Commit the candidate configuration to the running configuration. |
(config)# exit | Exit configure terminal mode |
#clear ip bgp peer-group ABC soft in | Do inbound soft reset for the peer-group ABC for the policy to take affect for the peer-group members |
Validation
R1
R1#show ip bgp
BGP table version is 7, local router ID is 1.1.1.1
Status codes: s suppressed, d damped, h history, a add-path, g group-best, * valid, > best, i - internal, l - labeled
S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*> 1.1.1.1/32 0.0.0.0 0 100 32768 i
*> 11.11.11.11/32 0.0.0.0 0 100 32768 i
*>i 22.1.1.0/24 2.2.2.2 0 100 0 i
* i 3.3.3.3 0 100 0 i
Total number of prefixes 3
Peer group members can be configured with Inbound Policies
R1
#configure terminal | Enter configure mode. |
(config)#ip access-list permit-100 | Configure access-list to permit 100.1.1.0/24 |
(config-ip-acl)# permit any 100.1.1.0/24 any | Configure a permit statement to permit 100.1.1.0/24 |
(config-ip-acl)#exit | Exit ip access-list mode |
(config)#route-map permit-only-100 | Configure route-map |
(config-route-map)#match ip address permit- 100 | Configure match statement in route-map to match the access- list permit-100 |
(config-route-map)#exit | Exit route-map mode |
(config)#router bgp 200 | Enter BGP router mode |
(config)# address-family ipv4 unicast | Enter address-family ipv4 unicast mode |
(config-router-af)# neighbor 2.2.2.2 activate | Activate neighbor in the address family |
(config-router-af)#neighbor 2.2.2.2 route- map permit-only-100 in | Configure the peer-group-member R2(2.2.2.2) with route-map in the inbound direction |
(config-router-af)#exit | Exit address-family mode |
(config-router)#exit | Exit router bgp mode |
(config-router)#commit | Commit the candidate configuration to the running configuration. |
(config)# exit | Exit configure terminal mode |
#clear ip bgp peer-group ABC soft in | Do inbound soft reset for the peer-group ABC for the policy to take affect for the peer-group members |
Validation
R1
R1#show ip bgp
BGP table version is 4, local router ID is 10.12.65.126
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
l - labeled, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*> 1.1.1.1/32 0.0.0.0 0 100 32768 i
*> 11.11.11.11/32 0.0.0.0 0 100 32768 i
*>i 22.1.1.0/24 3.3.3.3 0 100 0 i
*>i 100.1.1.0/24 2.2.2.2 0 100 0 i
Total number of prefixes 4
R1#
Last modified date: 10/16/2023