Route Reflector
The configurations in this section apply to BGP Route Reflectors (RR).
Reduce the iBGP Mesh Inside an Autonomous System
Use Route Reflectors to reduce the iBGP mesh inside an Autonomous System (AS).
Topology
In this example, R2, R5, and R4 would have to maintain a full mesh among themselves, but by making R5 the Route Reflector, R2 (Client1) has an iBGP session with the RR only, but not with R4 (Client 2). The routes learned from R2 are advertised to the other clients, and to iBGP peers outside the cluster; the iBGP routes learned from iBGP peers outside the cluster are advertised to R2. This reduces the iBGP peer connections in AS1.
Figure 1-4: BGP Route Reflector
RR (R5)
#configure terminal | Enter configure mode. |
(config)#router bgp 1 | Define the routing process. The number 1 identifies the AS number of R5. |
(config-router)#neighbor 10.10.10.50 remote-as 1 | Define the BGP neighbor, and establish a TCP session. 10.10.10.50 is the IP address of one of the neighbors (R2), and 1 is the neighbor's AS number. |
(config-router)#neighbor 10.10.11.50 remote-as 1 | Define the BGP neighbor, and establish a TCP session. 10.10.11.50 is the IP address of one of the neighbors (R4), and 1 is the neighbor's AS number. |
(config-router)# address-family ipv4 unicast | Enter address-family ipv4 unicast mode |
(config-router-af)# neighbor 10.10.10.50 activate | Activate the neighbor in the Ipv4 address family. |
(config-router-af)#neighbor 10.10.11.50 activate | Activate the neighbor in the Ipv4 address family. |
(config-router-af)#neighbor 10.10.10.50 route-reflector-client | Configure R5 as the Route-Reflector (RR) and neighbor R2 as its client. |
(config-router-af)#neighbor 10.10.11.50 route-reflector-client | Configure R5 as the Route-Reflector (RR) and neighbor R4 as its client. |
(config-router-af)#exit-address-family | Exit address-family mode. |
(config-router)#commit | Commit the candidate configuration to the running configuration. |
RR Client 1 (R2)
(config)#router bgp 1 | Define the routing process. The number 1 specifies the AS number of R2. |
(config-router)#neighbor 10.10.10.10 remote-as 1 | Define the BGP neighbor, and establish a TCP session. 10.10.10.10 is the IP address of the neighbor (R5), and 1 is the neighbor’s AS number. |
(config-router)# address-family ipv4 unicast | Enter address-family ipv4 unicast mode |
(config-router-af)# neighbor 10.10.10.10 activate | Activate the neighbor in the Ipv4 address family. |
(config-router-af)#exit-address-family | Exit address-family mode. |
(config-router)#exit | Exit router mode. |
(config)#commit | Commit the candidate configuration to the running configuration. |
RR Client 2 (R4)
(config)#router bgp 1 | Define the routing process. The number 1 identifies the AS number of R4. |
(config-router)#neighbor 10.10.11.10 remote-as 1 | Define BGP neighbor, and establish a TCP session. 10.10.11.10 is the IP address of the neighbor (R5), and 1 is the neighbor’s AS number. |
(config-router)# address-family ipv4 unicast | Enter address-family ipv4 unicast mode |
(config-router-af)# neighbor 10.10.11.10 activate | Activate the neighbor in the Ipv4 address family. |
(config-router-af)#exit-address-family | Exit address-family mode. |
(config-router)#exit | Exit router mode. |
(config)#commit | Commit the candidate configuration to the running configuration. |
Validation
R5
#show ip bgp neighbors
BGP neighbor is 10.10.10.50, remote AS 1, local AS 1, internal link
BGP version 4, local router ID 192.160.50.3, remote router ID 10.12.4.152
BGP state = Established, up for 00:01:04
Last read 00:01:04, 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 4 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
Route-Reflector Client
Community attribute sent to this neighbor (both)
0 accepted prefixes
0 announced prefixes
Connections established 1; dropped 0
Local host: 10.10.10.10, Local port: 47983
Foreign host: 10.10.10.50, Foreign port: 179
Nexthop: 10.10.10.10
Nexthop global: fe80::a00:27ff:fe09:fd25
Nexthop local: ::
BGP connection: non shared network
BGP neighbor is 10.10.11.50, remote AS 1, local AS 1, internal link
BGP version 4, remote router ID 10.12.4.197
local router ID 192.160.50.3
BGP state = Established, up for 00:01:04
Last read 00:01:04, 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 4 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
Route-Reflector Client
Community attribute sent to this neighbor (both)
0 accepted prefixes
0 announced prefixes
Connections established 1; dropped 0
Local host: 10.10.11.10, Local port: 39851
Foreign host: 10.10.11.50, Foreign port: 179
Nexthop: 10.10.11.10
Nexthop global: fe80::a00:27ff:fe52:45f6
Nexthop local: ::
BGP connection: non shared network
R3
#show ip bgp neighbors
BGP neighbor is 10.10.11.10, remote AS 1, local AS 1, internal link
BGP version 4, local router ID 192.160.50.4, remote router ID 10.12.4.185
BGP state = Established, up for 00:00:56
Last read 00:00:56, 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 3 messages, 0 notifications, 0 in queue
Sent 3 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
Community attribute sent to this neighbor (both)
0 accepted prefixes
0 announced prefixes
Connections established 1; dropped 0
Local host: 10.10.11.50, Local port: 179
Foreign host: 10.10.11.10, Foreign port: 39851
Nexthop: 10.10.11.50
Nexthop global: fe80::a00:27ff:fe42:fb7a
Nexthop local: ::
BGP connection: non shared network
R2
#show ip bgp neighbors
BGP neighbor is 10.10.10.10, remote AS 1, local AS 1, internal link
BGP version 4, local router ID 192.160.50.2, remote router ID 10.12.4.185
BGP state = Established, up for 00:01:23
Last read 00:01:23, 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 4 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
Community attribute sent to this neighbor (both)
0 accepted prefixes
0 announced prefixes
Connections established 1; dropped 0
Local host: 10.10.10.50, Local port: 179
Foreign host: 10.10.10.10, Foreign port: 47983
Nexthop: 10.10.10.50
Nexthop global: fe80::a00:27ff:fe9c:f35d
Nexthop local: ::
BGP connection: non shared network
Last modified date: 10/16/2023