[Xorp-users] Advertising same route from two BGP peers

[Arsi Antila]

XORP has two BGP peers, which both advertise route 14.14.14.0/24. If
there is a simple policy rule in the XORP configuration, then both
routes are marked 'Winner'. If there is no policy rule, only one of the
routes is marked 'Winner'. Is this expected behaviour?

When XORP is started with 'bgp1.boot' as parameter, 'show bgp routes
detail' shows the following:

> show bgp routes detail
14.14.14.0/24
        From peer: 10.1.0.2
        Route: Winner
        Origin: IGP
        AS Path: 1114
        Nexthop: 10.1.0.2
        Multiple Exit Discriminator: 0
14.14.14.0/24
        From peer: 11.1.0.2
        Route: Not Used
        Origin: IGP
        AS Path: 1112
        Nexthop: 11.1.0.2
        Multiple Exit Discriminator: 0



If XORP is started with 'bgp2.boot' as parameter, both routes are marked
'Winner'. In addition, if BGP peer 10.1.0.2 is restarted, XORP BGP
process dies (this situation is similar, but simpler, to the situation
described in my previous mail "BGP crash".


> show bgp routes detail
14.14.14.0/24
        From peer: 11.1.0.2
        Route: Winner
        Origin: IGP
        AS Path: 1112
        Nexthop: 11.1.0.2
        Multiple Exit Discriminator: 0
14.14.14.0/24
        From peer: 10.1.0.2
        Route: Winner
        Origin: IGP
        AS Path: 1114
        Nexthop: 10.1.0.2
        Multiple Exit Discriminator: 0



-------- bgp1.boot -------------
interfaces {
  restore-original-config-on-shutdown: false
  interface eth1 {
    default-system-config
  }
  interface eth1.10 {
    default-system-config
  }
  interface eth1.11 {
    default-system-config
  }
}

protocols {
  bgp {
    bgp-id: 10.1.0.1
    local-as: 1113
    peer 10.1.0.2 {
      local-ip: 10.1.0.1
      as: 1114
      next-hop: 10.1.0.1
    }
    peer 11.1.0.2 {
      local-ip: 11.1.0.1
      as: 1112
      next-hop: 11.1.0.1
    }
  }
}

------ bgp2.boot ----
interfaces {
  restore-original-config-on-shutdown: false
  interface eth1 {
    default-system-config
  }
  interface eth1.10 {
    default-system-config
  }
  interface eth1.11 {
    default-system-config
  }
}

policy {
  policy-statement bgp_export_policy {
    term a1 {
      from {
        protocol: "bgp"
      }
      then {
        accept
      }
    }
  }
}

protocols {
  bgp {
    export: "bgp_export_policy"
    bgp-id: 10.1.0.1
    local-as: 1113
    peer 10.1.0.2 {
      local-ip: 10.1.0.1
      as: 1114
      next-hop: 10.1.0.1
    }
    peer 11.1.0.2 {
      local-ip: 11.1.0.1
      as: 1112
      next-hop: 11.1.0.1
    }
  }
}