EIGRP and Distance command

I am trying to filter based on distance with eigrp. I want to filter the out the 103 network. I cannot get it to work. everything looks right. What am I missing here?

router eigrp af

  address-family ipv4 unicast autonomous-system 1

   topology base

   distance 255 0.0.0.0 255.255.255.255 2

    exit-af-topology

  exit-address-family

______________________________________________________

r1#show run | sec access-list 2

access-list 2 permit 150.1.103.0 0.0.0.255

______________________________________________________

r1#show ip route 150.1.103.0

Routing entry for 150.1.103.0/24

  Known via "eigrp 1", distance 170, metric 5176320, type external

  Redistributing via eigrp 1

  Last update from 155.1.1.2 on GigabitEthernet1.12, 00:00:44 ago

  Routing Descriptor Blocks:

  * 156.1.1.2, from 156.1.1.2, 00:00:44 ago, via GigabitEthernet1.21

      Route metric is 5176320, traffic share count is 1

      Total delay is 110 microseconds, minimum bandwidth is 1000 Kbit

      Reliability 255/255, minimum MTU 1500 bytes

      Loading 1/255, Hops 1

    155.1.1.2, from 155.1.1.2, 00:00:44 ago, via GigabitEthernet1.12

      Route metric is 5176320, traffic share count is 1

      Total delay is 110 microseconds, minimum bandwidth is 1000 Kbit

      Reliability 255/255, minimum MTU 1500 bytes

      Loading 1/255, Hops 1

____________________________________________________________________________

r1#show ip eigrp top 150.1.103.0/24

EIGRP-IPv4 VR(af) Topology Entry for AS(1)/ID(156.1.1.1) for 150.1.103.0/24

  State is Passive, Query origin flag is 1, 2 Successor(s), FD is 662568960, RIB is 5176320

  Descriptor Blocks:

  155.1.1.2 (GigabitEthernet1.12), from 155.1.1.2, Send flag is 0x0

      Composite metric is (662568960/661913600), route is External

      Vector metric:

        Minimum bandwidth is 1000 Kbit

        Total delay is 110000000 picoseconds

        Reliability is 255/255

        Load is 1/255

        Minimum MTU is 1500

        Hop count is 1

        Originating router is 150.1.2.2

      External data:

        AS number of route is 0

        External protocol is Connected, external metric is 0

        Administrator tag is 0 (0x00000000)

  156.1.1.2 (GigabitEthernet1.21), from 156.1.1.2, Send flag is 0x0

      Composite metric is (662568960/661913600), route is External

      Vector metric:

        Minimum bandwidth is 1000 Kbit

        Total delay is 110000000 picoseconds

        Reliability is 255/255

        Load is 1/255

        Minimum MTU is 1500

        Hop count is 1

        Originating router is 150.1.2.2

      External data:

        AS number of route is 0

        External protocol is Connected, external metric is 0

        Administrator tag is 0 (0x00000000)

r1#

Comments

  • It's because of the external route. As far is I it is not possible to change the AD for external routes in EIGRP on a per prefix basis.

    I think this has to do with the loop prevention.

  • Thanks Marten, that was it. The only way I know to adjust distance for EX routes is though this command but the side effect it is does it for all routes vs just secleted routes. Thanks for you help on that.

    r2(config-router-af-topology)#distance eigrp 255 ?
      <1-255>  Distance for external routes

  • You cannot have per-prefix AD in EIGRP for external routes.

    Sent from my iPhone

    On Aug 11, 2015, at 22:46, JustINcase <[email protected]> wrote:

    I am trying to filter based on distance with eigrp. I want to filter the out the 103 network. I cannot get it to work. everything looks right. What am I missing here?

    router eigrp af

      address-family ipv4 unicast autonomous-system 1

       topology base

       distance 255 0.0.0.0 255.255.255.255 2

        exit-af-topology

      exit-address-family

    ______________________________________________________

    r1#show run | sec access-list 2

    access-list 2 permit 150.1.103.0 0.0.0.255

    ______________________________________________________

    r1#show ip route 150.1.103.0

    Routing entry for 150.1.103.0/24

      Known via "eigrp 1", distance 170, metric 5176320, type external

      Redistributing via eigrp 1

      Last update from 155.1.1.2 on GigabitEthernet1.12, 00:00:44 ago

      Routing Descriptor Blocks:

      * 156.1.1.2, from 156.1.1.2, 00:00:44 ago, via GigabitEthernet1.21

          Route metric is 5176320, traffic share count is 1

          Total delay is 110 microseconds, minimum bandwidth is 1000 Kbit

          Reliability 255/255, minimum MTU 1500 bytes

          Loading 1/255, Hops 1

        155.1.1.2, from 155.1.1.2, 00:00:44 ago, via GigabitEthernet1.12

          Route metric is 5176320, traffic share count is 1

          Total delay is 110 microseconds, minimum bandwidth is 1000 Kbit

          Reliability 255/255, minimum MTU 1500 bytes

          Loading 1/255, Hops 1

    ____________________________________________________________________________

    r1#show ip eigrp top 150.1.103.0/24

    EIGRP-IPv4 VR(af) Topology Entry for AS(1)/ID(156.1.1.1) for 150.1.103.0/24

      State is Passive, Query origin flag is 1, 2 Successor(s), FD is 662568960, RIB is 5176320

      Descriptor Blocks:

      155.1.1.2 (GigabitEthernet1.12), from 155.1.1.2, Send flag is 0x0

          Composite metric is (662568960/661913600), route is External

          Vector metric:

            Minimum bandwidth is 1000 Kbit

            Total delay is 110000000 picoseconds

            Reliability is 255/255

            Load is 1/255

            Minimum MTU is 1500

            Hop count is 1

            Originating router is 150.1.2.2

          External data:

            AS number of route is 0

            External protocol is Connected, external metric is 0

            Administrator tag is 0 (0x00000000)

      156.1.1.2 (GigabitEthernet1.21), from 156.1.1.2, Send flag is 0x0

          Composite metric is (662568960/661913600), route is External

          Vector metric:

            Minimum bandwidth is 1000 Kbit

            Total delay is 110000000 picoseconds

            Reliability is 255/255

            Load is 1/255

            Minimum MTU is 1500

            Hop count is 1

            Originating router is 150.1.2.2

          External data:

            AS number of route is 0

            External protocol is Connected, external metric is 0

            Administrator tag is 0 (0x00000000)

    r1#




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  • This is really interesting, I didn't know you couldn't set the AD on a per prefix basis for external EIGRP routes. Which leads me to wondering, what other options do you actually have to filter this external route out? Is it only possible to stop these routes being installed into the EIGRP process using the distribute-list command? I actually can't think of any other way.

  • Hi sg4rbo,  I have tried to captue every way to filter. The only thing I can think of would be maybe a offset lists to set the metric so high that you perfer anohter route. (if one exists that is). If the external routes had more hops you could also use Max hops command. In my case they didnt.  If I am missing a way to filter let me know.

    But you to your point besides using the DLs there does not really seem to be any other way to do that unless the stars align and you have additional routes or multiple hops. (that I can find at any rate)

    1. Passive Interface

    2. distribut-list with deny  std acl

    3. distribute-list with deny ext acl

    5 distribute-list with deny prefix list

    6. distribute-list with deny prefix list  then gateway key word then premit prefix list with neighbor address

    7. distribute-list with deny route map using TAGs

    8. offset list with permit acl

    9. distnace with std acl

    10. distance with neighbor address and permit std acl.

    11. set defualt distance for all internal and eternal routes

    12. set maximum hops

    13. apply ext acl to interface deny protocol 88 and 224.0.0.10

     

  • Hi All,

    Good post.

    If you use an offset list, using new code, does it alter the delay value of route?  And does it advertise new delay value downstream?  In old code, if you altered offset in blocks of 256, appeared to alter delay by plus 1.  <from recollection>

    Like you said, offset cost so high that it becomes an invalid route.  It seems then that it wouldn't be inserted in local route table.  Not advertised/distributed at all.

    I like tagging.

  • I don't think you can set the metric too high in the old code. It's only the new code that you can set the metric too high I think!

  • Hi SG and All,

    Been a while!  Yeah, I've gotten rusty with all this stuff (as I transitioned to Juniper).  The offset in blocks of 255 sticks in my mind cause someone said that it wasn't possible to perform Traffic Engineering using an offset list within EIGRP, as the effect of an offset is not passed along within an update.   So I labbed it.  And the delay parameter increases when offset is greater than 255, and that delay change is propagated.  -- IOS 12.4

    Keeping it out of the local route table?  mmm can't recall that I ever labbed EIGRP with that goal in mind.

    Will attempt//Thanks for keeping me on track//RandyB

    Performed an attempt:  

    Trial 1:  offset-list 0 in 2147483647    Result:  route still valid;

    Trial 2:    offset-list 0 in 2147483647; with bandwidth 1   Result: route invalid   

    Yeah, I know.  I skirted the requirements with the second Trial.  So, offset list doesnt allow one to keep out of local route table, using IOS 12.4

  • In general, it is not recommended to filter a route from the RIB by using AD of 255 or big enough offset; if the routing protocol supports it(all except link-state and this is by design), why don't you filter the route at the database/topology level to begin with, by using the distribute-list and attach a ACL, prefix-list or route-map.

  • As using offset-list you will modify the delay value in the vector metric components from the EIGRP topology, the offset affects both local EIGRP topology and RIB, as well as downstream neighbors; it is always been like this.

  • Hi Cristian and All, 

    Adding further about offset lists and classic eigrp:

    With Classic eigrp and its 256 factoring (narrow metrics), a command like:

    "offset-list 0 in 1"

    would not alter any propagated DLY parameter.  Its change in EIGRP DLY is +1/256

    "Within an offset-list and using eigrp narrow metrics, offset increments of 256 increases propagated DLY; for example,

    offset-list 0 in 256

    would result in a change of EIGRP DLY by +1".

    Not saying that above is correct.  Just that this is my understanding when using 12.4// RandyB

  • Offset-list will affect both the local EIGRP topology and local RIB, as well as downstream EIGRP neighbors topoloty and RIB, regardless on how you run EIGRP:named or classic mode. The only difference is if the offset-list affect both the AD and FD computation, or only the FD: in older codes it used to affect only the FD, newer codes it affects both FD and AD.

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