OSPF tags

Hi. 

 

I was working on tags with OSPF, so I redistributed some routes to an NSSA area and added some tags to them by a route-map. the routers inside NSSA area see the routes with tags but routers outside the NSSA area don't see tags. I don't think that ABR routers block the tags while generating Type 5 LSAs. Am I wrong or what?

Comments

  • In my case it did work. I redistributed a loopback in the NSSA area and it did show the tag in the NSSA Area routing table and database also the tag was shown in the Area 0 and a normal area.

    Did you do anything special?

    Here is my output:

    ------------NSSA Area---------------


    Routing entry for 100.100.100.100/32

      Known via "ospf 1", distance 110, metric 20

      Tag 100, type NSSA extern 2, forward metric 2

      Last update from 10.0.12.2 on GigabitEthernet1.12, 00:34:00 ago

      Routing Descriptor Blocks:

      * 10.0.12.2, from 2.2.2.2, 00:34:00 ago, via GigabitEthernet1.12

          Route metric is 20, traffic share count is 1

          Route tag 100


                    Type-7 AS External Link States (Area 12)


    Link ID         ADV Router      Age         Seq#       Checksum Tag

    100.100.100.100 2.2.2.2         393         0x80000003 0x007C12 100


    ------------Regular and Backbone Area---------------


    Routing entry for 100.100.100.100/32

      Known via "ospf 1", distance 110, metric 20

      Tag 100, type extern 2, forward metric 3

      Last update from 10.0.13.1 on GigabitEthernet1.13, 00:34:18 ago

      Routing Descriptor Blocks:

      * 10.0.13.1, from 1.1.1.1, 00:34:18 ago, via GigabitEthernet1.13

          Route metric is 20, traffic share count is 1

          Route tag 100


                    Type-5 AS External Link States


    Link ID         ADV Router      Age         Seq#       Checksum Tag

    100.100.100.100 1.1.1.1         392         0x80000003 0x002F6D 100

  • ABRs don't block the tags. I just checked using the topology below. R3 redistributes a route (10.0.34.0/24) into OSPF.

    R1 -----Area0----- R2 ----NSSA---- R3

     

    R3#sh run | s router|route-map
    router ospf 1
     router-id 3.3.3.3
     log-adjacency-changes
     area 1 nssa
     redistribute connected subnets route-map tmp
    route-map tmp permit 10
     match interface FastEthernet0/0
     set tag 12345

    R2#sh ip ospf database nssa 10.0.34.0 | i Tag
            External Route Tag: 12345

    R1#sh ip ospf database external 10.0.34.0 | i Tag
            External Route Tag: 12345

    So it does work.

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