BGP supports multiple paths, allowing an ADVPN to advertise multiple paths. This allows BGP to extend and keep additional network paths according to RFC 7911.
In this example, Spoke1 and Spoke2 each have four VPN tunnels that are connected to the Hub with ADVPN. The Spoke-Hub has established four BGP neighbors on all four tunnels.
Spoke 1 and Spoke 2 can learn four different routes from each other.
To configure the hub:
config router bgp
set as 65505
set router-id 11.11.11.11
set ibgp-multipath enable
set additional-path enable
set additional-path-select 4
config neighbor-group
edit "gr1"
set capability-default-originate enable
set remote-as 65505
set additional-path both
set adv-additional-path 4
set route-reflector-client enable
next
end
config neighbor-range
edit 1
set prefix 10.10.0.0 255.255.0.0
set neighbor-group "gr1"
next
end
config network
edit 12
set prefix 11.11.11.11 255.255.255.255
next
end
end
To configure a spoke:
config router bgp
set as 65505
set router-id 2.2.2.2
set ibgp-multipath enable
set additional-path enable
set additional-path-select 4
config neighbor
edit "10.10.100.254"
set soft-reconfiguration enable
set remote-as 65505
set additional-path both
set adv-additional-path 4
next
edit "10.10.200.254"
set soft-reconfiguration enable
set remote-as 65505
set additional-path both
set adv-additional-path 4
next
edit "10.10.203.254"
set soft-reconfiguration enable
set remote-as 65505
set additional-path both
set adv-additional-path 4
next
edit "10.10.204.254"
set soft-reconfiguration enable
set remote-as 65505
set additional-path both
set adv-additional-path 4
next
end
config network
edit 3
set prefix 22.1.1.0 255.255.255.0
next
end
end
To view the BGP routing table on a spoke:
Spoke1 # get router info routing-table bgp
Routing table for VRF=0
B* 0.0.0.0/0 [200/0] via 10.10.200.254, vd2-2, 03:57:26
[200/0] via 10.10.203.254, vd2-3, 03:57:26
[200/0] via 10.10.204.254, vd2-4, 03:57:26
[200/0] via 10.10.100.254, vd2-1, 03:57:26
B 1.1.1.1/32 [200/0] via 11.1.1.1 (recursive via 12.1.1.1), 03:57:51
[200/0] via 11.1.1.1 (recursive via 12.1.1.1), 03:57:51
[200/0] via 11.1.1.1 (recursive via 12.1.1.1), 03:57:51
[200/0] via 11.1.1.1 (recursive via 12.1.1.1), 03:57:51
B 11.11.11.11/32 [200/0] via 10.10.200.254, vd2-2, 03:57:51
[200/0] via 10.10.203.254, vd2-3, 03:57:51
[200/0] via 10.10.204.254, vd2-4, 03:57:51
[200/0] via 10.10.100.254, vd2-1, 03:57:51
B 33.1.1.0/24 [200/0] via 10.10.204.3, vd2-4, 03:57:26
[200/0] via 10.10.203.3, vd2-3, 03:57:26
[200/0] via 10.10.200.3, vd2-2, 03:57:26
[200/0] via 10.10.100.3, vd2-1, 03:57:26
[200/0] via 10.10.204.3, vd2-4, 03:57:26
[200/0] via 10.10.203.3, vd2-3, 03:57:26
[200/0] via 10.10.200.3, vd2-2, 03:57:26
[200/0] via 10.10.100.3, vd2-1, 03:57:26
[200/0] via 10.10.204.3, vd2-4, 03:57:26
[200/0] via 10.10.203.3, vd2-3, 03:57:26
[200/0] via 10.10.200.3, vd2-2, 03:57:26
[200/0] via 10.10.100.3, vd2-1, 03:57:26
[200/0] via 10.10.204.3, vd2-4, 03:57:26
[200/0] via 10.10.203.3, vd2-3, 03:57:26
[200/0] via 10.10.200.3, vd2-2, 03:57:26
[200/0] via 10.10.100.3, vd2-1, 03:57:26