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bgp route question

Mike Schooley
Level 1
Level 1

so I have this output, the "local" route is appearing in my routing table via eigrp.  10.33.254.20 is not a bgp neigh, and 10.40.33.4 is this routers loopback.  The primary route should be via bgp.  Those routes are being redistirbuted int eigrp with a tag of 1000, then eigrp is being redistibuted back into bgp except for the tagged routes.  10.33.254.20 is actually our backup dmvpm router which is where the eigrp route is coming from, I just can't figure out why the bgp route isnt being put into the routing table instead of the eigrp route.  Note it is working correctly on about 50 sites and just about 10 are doing this.  Also if you look at an eigrp neigh, this route doesnt have the 1000 tag.  Perhaps, I am redistributing the route and learning the routes via dmvpn, and the dmvpn router has a better cost than the redistributed route, but bgp route should still be installed due to admin distance right?

router2#sho ip bgp 10.35.10.0

BGP routing table entry for 10.35.10.0/24, version 170673

Paths: (2 available, best #2, table Default-IP-Routing-Table)

  Advertised to update-groups:

        1    2

  65000 10

    147.225.157.153 from 147.225.157.153 (159.24.198.5)

      Origin IGP, localpref 100, valid, external

  Local

    10.33.254.20 from 0.0.0.0 (10.40.33.4)

      Origin incomplete, metric 25858816, localpref 100, weight 32768, valid, sourced, best

router2#sho ip route 10.35.10.0
Routing entry for 10.35.10.0/24
  Known via "eigrp 136", distance 90, metric 25858816, type internal
  Redistributing via eigrp 136, bgp 1
  Advertised by bgp 1 route-map eigrp_to_bgp
  Last update from 10.33.254.20 on FastEthernet0/0, 6d00h ago
  Routing Descriptor Blocks:
  * 10.33.254.20, from 10.33.254.20, 6d00h ago, via FastEthernet0/0
      Route metric is 25858816, traffic share count is 1
      Total delay is 10110 microseconds, minimum bandwidth is 100 Kbit
      Reliability 255/255, minimum MTU 1400 bytes
      Loading 198/255, Hops 2

19 Replies 19

so the route is in bgp and eigrp yet eigrp is in ip routing table

RC002VPN2#sho ip eigrp top 10.35.9.0/24
IP-EIGRP (AS 136): Topology entry for 10.35.9.0/24
  State is Passive, Query origin flag is 1, 1 Successor(s), FD is 25861120
  Routing Descriptor Blocks:
  10.33.254.20 (FastEthernet0/0), from 10.33.254.20, Send flag is 0x0
      Composite metric is (25861120/25858560), Route is Internal
      Vector metric:
        Minimum bandwidth is 100 Kbit
        Total delay is 10200 microseconds
        Reliability is 255/255
        Load is 56/255
        Minimum MTU is 1400
        Hop count is 2
RC002VPN2#sho ip bgp 10.35.9.0/24
BGP routing table entry for 10.35.9.0/24, version 170832
Paths: (2 available, best #2, table Default-IP-Routing-Table)
  Advertised to update-groups:
        1    2
  65000 9
    147.225.157.153 from 147.225.157.153 (159.24.198.5)
      Origin IGP, localpref 100, valid, external
  Local
    10.33.254.20 from 0.0.0.0 (10.40.33.4)
      Origin incomplete, metric 25861120, localpref 100, weight 32768, valid, sourced, best
RC002VPN2#sho ip route 10.35.9.0/24
                                ^
% Invalid input detected at '^' marker.

RC002VPN2#sho ip route 10.35.9.0
Routing entry for 10.35.9.0/24
  Known via "eigrp 136", distance 90, metric 25861120, type internal
  Redistributing via eigrp 136, bgp 1
  Advertised by bgp 1 route-map eigrp_to_bgp
  Last update from 10.33.254.20 on FastEthernet0/0, 6d09h ago
  Routing Descriptor Blocks:
  * 10.33.254.20, from 10.33.254.20, 6d09h ago, via FastEthernet0/0
      Route metric is 25861120, traffic share count is 1
      Total delay is 10200 microseconds, minimum bandwidth is 100 Kbit
      Reliability 255/255, minimum MTU 1400 bytes
      Loading 56/255, Hops 2

So I see


BGP routing table entry for 10.35.9.0/24, version 170832
Paths: (2 available, best #2, table Default-IP-Routing-Table)
Advertised to update-groups:
1    2
65000 9
147.225.157.153 from 147.225.157.153 (159.24.198.5)
Origin IGP, localpref 100, valid, external

Local
10.33.254.20 from 0.0.0.0 (10.40.33.4)
Origin incomplete, metric 25861120, localpref 100, weight 32768, valid, sourced, best

IMHO, you need to configure something like:

router bgp 1

redistribute eigrp 136 route-map eigrp-to-bgp

route-map eigrp-to-bgp deny 10

match tag 1000

route-map eigrp-to-bgp permit 20

set local-preference 50

set weight 0

HTH,

Milan

that may fix it but it doesnt answer the core question here, why is the eigrp route in the routing table instead of the bgp route.  If the bgp route was in the routing table, this would all be moot as there would be no eigrp route to redistirbute, and since the bgp route has an admin distance of 20 vs 90 for eigrp, I'm kind of confused.

Because from BGP process point of view the best route is that one which had been redistributed from EIGRP.

As it was only redistributed, it can't be handled like a BGP route, it's still an EIGRP route from the RIB point of view.

If you try my fix, you'll see the route coming from eBGP will become the best one from the BGP process point of view and will also be installed into the RIB as a BGP route.

BR,

Milan

ok, I think I am going to set the weight on all of my bgp routes to > 32768, thanks for your help.

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