Route selection using MED

[xianglong han]

Hi, all

I am building a BGP and OSPF network specified in RFC 3345 which will lead
to a BGP oscillation. see below:

      ---------------------------------------------------------------
    /     --------------------               --------------------     \
   |    /                      \           /                      \    |
   |   |       Cluster 1        |         |      Cluster 2         |   |
   |   |                        |         |                        |   |
   |   |                        |   *1    |                        |   |
   |   |         Ra(RR) . . . . . . . . . . . . . . Rd(RR)         |   |
   |   |         .  .           |         |           .            |   |
   |   |       .*5    .*4       |         |           .*12         |   |
   |   |     .          .       |         |           .            |   |
   |   |   Rb(C)        Rc(C)   |         |         Re(C)          |   |
   |   |     .            .     |         |           .            |   |
   |    \    .            .    /           \          .           /    |
   |      ---.------------.---               ---------.----------      |
    \        .(10)        .(1)     AS1                .(0)            /
      -------.------------.---------------------------.--------------
             .            .                           .
          ------            .     ------------      .
        /        \            . /              \   .
       |   AS10   |            |      AS6       |
        \        /              \              /
          ------                  ------------
                .                      .
                   .                   .
                      .       --------------
                         .  /                \
                           |      AS100       |- 10.0.0.0/8
                            \                /
                              --------------



The problem is, the router Rd does not perform as expected in selecting the
best route.

10.199.0.0/16      via 10.1.7.2 on eth2 [SR 14:30] * (100-/5) [AS65002i]
        Type: BGP unicast univ
        BGP.origin: IGP
        BGP.as_path: 65002
        BGP.next_hop: 10.1.5.2
        BGP.med: 1
        BGP.local_pref: 100
        BGP.originator_id: 10.1.4.2
        BGP.cluster_list: 10.1.3.3
                   via 10.1.1.2 on eth3 [SC 14:29] (100/12) [AS65002i]
        Type: BGP unicast univ
        BGP.origin: IGP
        BGP.as_path: 65002
        BGP.next_hop: 10.1.1.2
        BGP.med: 0


Should the second route in the above route table be better? as it has a
lower med value with the local preference, AS path length and orgins.

Thanks
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