BGP multiple path support

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