Border Gateway Protocol (BGP)

Configuring ECMP support for BGP

“ECMP” stands for “Equal Cost Multiple Path”. ECMP is a mechanism that allows multiple routes to the same destination with different next-hops and load-balances routed traffic over those multiple next-hops.

  • ECMP only works for routes that are sourced by the same routing protocol (that is: Static Routes, OSPF, or BGP).
  • ECMP is enabled by default with 10 paths.
  • ECMP with static routes is effective if the routes are configured with the same distance and same priority.

To configure ECMP support – CLI

config router bgp

set ebgp-multipath disable[|enable]

set ibgp-multipath disable[|enable]

… end

 

Testing network configuration

Testing this configuration involves the standard connectivity checks, but also ensuring that routes are being passed between protocols as expected.

Check the routing table on the FortiGate unit to ensure that routes from both OSPF and BGP are present. Check the routing table on devices on the OSPF network for routes redistributed from BGP. Also check those devices for connectivity to the Internet.

Check the routing table on Peer 2 to ensure no routes from Peer 1 are present, but routes from the internal OSPF network are present.

For help with troubleshooting, see Redistributing and blocking routes in BGP on page 369.

 

6 thoughts on “Border Gateway Protocol (BGP)

  1. piccolo

    Hi Mike,
    if i configure the following on fortigate1:
    config router bgp
    set as 65000
    set router-id 10.2.2.254
    config neighbor
    edit “10.2.2.253”
    set next-hop-self enable
    set remote-as 65000
    set send-community6 disable
    next

    config redistribute “static”
    set status enable
    end

    fortigate2 should get the default route 0.0.0.0 0.0.0.0 from fortigate1 as it is static ?

    how can i redistribute the default route(fortigate1) to fortigate2 ?

    thanks
    regards

    Reply
    1. Mike Post author

      There is a really good KB article that explains how to do this. You can find it here

      If you want to redistribute static routes you would enable the following

      config router bgp
      config redistribute static
      set status enable
      end
      end

      An example of the config would be like this

      config router prefix-list
      edit “only_dflt”
      config rule
      edit 1
      set prefix 0.0.0.0 0.0.0.0
      unset ge
      unset le
      next
      end
      next
      end

      config router route-map
      edit “only_default_route”
      config rule
      edit 1
      set match-ip-address “only_dflt”
      next
      end
      next
      end

      config router bgp
      set as 2
      config neighbor
      edit 10.142.0.110
      set remote-as 1
      set route-map-in “only_default_route”
      next
      end

      set router-id 10.142.0.205
      end

      Let me know if this helped answer your question!

      Thanks!

      Reply
  2. kamal

    config router bgp
    set as 65041
    set router-id 162.53.156.138
    config neighbor
    edit “10.104.55.1”
    set ebgp-enforce-multihop enable
    set soft-reconfiguration enable
    set remote-as 64699
    set send-community6 disable
    next
    edit “10.104.55.2”
    set ebgp-enforce-multihop enable
    set soft-reconfiguration enable
    set remote-as 64699
    set send-community6 disable
    next

    i am trying to accomplish above but i can see only one neighbour is establish and other is in ACTIVE state…

    Reply

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