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Table of Contents

Administration Guide

Next hop recursive resolution using ECMP routes

When there are multiple ECMP routes to a BGP next hop, all of them are considered for the next hop recursive resolution. This ensures that the outgoing traffic can be load balanced.

Note

To support multipath, either EGBP or IGBP multipath must be enabled:

config router bgp
    set ebgp-multipath enable
    set ibgp-multipath enable
end

In this example, there are two static routes. The FortiGate has learned two BGP routes from Router 1 that have the same next hop at 10.100.100.1. The next hop is resolved by the two static routes.

To verify that the routes are added to the BGP routing table:
  1. Check the two static routes:

    # get router info routing-table static
    Routing table for VRF=0
    S       10.100.100.0/24 [10/0] via 172.16.200.55, port9
                            [10/0] via 172.16.203.2, agg1
  2. Confirm that both routes are in the BGP routing table:

    # get router info routing-table bgp
    Routing table for VRF=0
    B       10.100.10.0/24 [20/200] via 10.100.100.1 (recursive via 172.16.200.55, port9), 00:00:07
                                                     (recursive via 172.16.203.2, agg1), 00:00:07
    B       10.100.11.0/24 [20/200] via 10.100.100.1 (recursive via 172.16.200.55, port9), 00:00:07
                                                     (recursive via 172.16.203.2, agg1), 00:00:07

Next hop recursive resolution using ECMP routes

When there are multiple ECMP routes to a BGP next hop, all of them are considered for the next hop recursive resolution. This ensures that the outgoing traffic can be load balanced.

Note

To support multipath, either EGBP or IGBP multipath must be enabled:

config router bgp
    set ebgp-multipath enable
    set ibgp-multipath enable
end

In this example, there are two static routes. The FortiGate has learned two BGP routes from Router 1 that have the same next hop at 10.100.100.1. The next hop is resolved by the two static routes.

To verify that the routes are added to the BGP routing table:
  1. Check the two static routes:

    # get router info routing-table static
    Routing table for VRF=0
    S       10.100.100.0/24 [10/0] via 172.16.200.55, port9
                            [10/0] via 172.16.203.2, agg1
  2. Confirm that both routes are in the BGP routing table:

    # get router info routing-table bgp
    Routing table for VRF=0
    B       10.100.10.0/24 [20/200] via 10.100.100.1 (recursive via 172.16.200.55, port9), 00:00:07
                                                     (recursive via 172.16.203.2, agg1), 00:00:07
    B       10.100.11.0/24 [20/200] via 10.100.100.1 (recursive via 172.16.200.55, port9), 00:00:07
                                                     (recursive via 172.16.203.2, agg1), 00:00:07