If possible to know in ospf which networks are received from a no passive interface?



Hi Guys 
I wanted to ask your help with one question about OSPF , I had try to find any information but i was not able to found it .  I need to  know exactly which routes are received from  OSPF neighbor 
 for example:  I have a core Switch with has several L3 switches connected and in the same campus (let’s call this campus C) and this core switches also talks ospf with two main campus  (A & B) which received several networks from f others mini campus (D to Z)  and all this networks are received on  Core switches on the campus  C and bellow to the same area 0,  I have tried to found an approach to find which network are originated on all the access Switch (l3 Switch) without need to look the route table of all the Access switched connected to the CORES (on Campus C) .  I suppose that should be a quick way to do this.  
my problem is that I can not trust on all the ospf network on the core due this is connect to other 2 campus and received several network.  Maybe there is some way to find this information on the ospf database or maybe knowing the no passive interfaces.
I wanted to do something similar to sho ip bgp neigh x.x.x.x routes but after my research  I have not being able to find  any similar command,  I know that they work very different ,  
I just say it because the input that I expect to find is similar to that command.

Note: these SW are on a production environment and I can not use any configuration or debug I must use SHOWs commands

Thanks For your help 


Comments

  • JoeMJoeM ✭✭✭

    Wow!   This sound like someone needs to create a network map.  Some discovery is needed.

    OSPF database entries can be laid out (map drawn).  Connecting the routers, areas, and redistribution points.

    Here is an really good article by Rene of gns3vault.com fame.

                   How to read an OSPF database

     

    For a simple search....this is what I would do. @anyone, feel free to add or make this thinking better.  ;-)

    1.  sh ip route x.x.x.x

    This will tell you the specific OSPF route (y.y.y.y) and the type of OSPF.

     

    2.  show ip ospf database <type> y.y.y.y

    This will give the ospf database entry for y.y.y.y (and all of the information like AREA and forwarding address).

     

    3.   depends on output of step 2.   I likely would follow the clue to the advertising router (which is likely an ABR).

     

    The thing about OSPF is that it is link-state within an area (and all have the same exact database), but between areas it is more like distance vector -- "routing by rumor" (trusting what my neighbor told me).

     

    This looks like an interesting project.   If you have time, take a look at that article I posted above.   It is the most simple explanation that I think I have ever seen about drawing a map directly from an OSPF database.

  • JoeMJoeM ✭✭✭

    As for the title of this thread:  

     If possible to know in ospf which networks are received from a no passive interface?

     

    First find the neighbors on that specific interface. This will narrow your focus.

             show ip ospf neighbors

     

    Then let's see a couple of other interesting commands from Rene's article:

    He goes into detail on the meaning of everything....as he hops from router to router gathering information.

     

    =====================

    R4#      show ip ospf database router 1.1.1.1

                OSPF Router with ID (4.4.4.4) (Process ID 1)

            Router Link States (Area 0)

      LS age: 175
      Options: (No TOS-capability, DC)
      LS Type: Router Links
      Link State ID: 1.1.1.1
      Advertising Router: 1.1.1.1

      LS Seq Number: 8000000E
      Checksum: 0xDDC0
      Length: 120
      Number of Links: 8

        Link connected to: another Router (point-to-point)
         (Link ID) Neighboring Router ID: 3.3.3.3
         (Link Data) Router Interface address: 10.0.123.1
          Number of TOS metrics: 0
           TOS 0 Metrics: 10

        Link connected to: another Router (point-to-point)
         (Link ID) Neighboring Router ID: 4.4.4.4
         (Link Data) Router Interface address: 10.0.123.1
          Number of TOS metrics: 0
           TOS 0 Metrics: 10

        Link connected to: another Router (point-to-point)
         (Link ID) Neighboring Router ID: 2.2.2.2
         (Link Data) Router Interface address: 10.0.123.1
          Number of TOS metrics: 0
           TOS 0 Metrics: 10

        Link connected to: a Stub Network
         (Link ID) Network/subnet number: 10.0.123.1
         (Link Data) Network Mask: 255.255.255.255
          Number of TOS metrics: 0
           TOS 0 Metrics: 0

        Link connected to: another Router (point-to-point)
         (Link ID) Neighboring Router ID: 5.5.5.5
         (Link Data) Router Interface address: 10.0.15.1
          Number of TOS metrics: 0
           TOS 0 Metrics: 12

        Link connected to: a Stub Network
         (Link ID) Network/subnet number: 10.0.15.0
         (Link Data) Network Mask: 255.255.255.0
          Number of TOS metrics: 0
           TOS 0 Metrics: 12

        Link connected to: another Router (point-to-point)
         (Link ID) Neighboring Router ID: 2.2.2.2
         (Link Data) Router Interface address: 10.0.12.1
          Number of TOS metrics: 0
           TOS 0 Metrics: 20

        Link connected to: a Stub Network
         (Link ID) Network/subnet number: 10.0.12.0
         (Link Data) Network Mask: 255.255.255.0
          Number of TOS metrics: 0
           TOS 0 Metrics: 20

     

    =============

    R3#  show ip ospf database router self-originate <--local

                OSPF Router with ID (3.3.3.3) (Process ID 1)

            Router Link States (Area 0)

      LS age: 11
      Options: (No TOS-capability, DC)
      LS Type: Router Links
      Link State ID: 3.3.3.3
      Advertising Router: 3.3.3.3

      LS Seq Number: 80000006
      Checksum: 0x67B0
      Length: 96
      Number of Links: 6

        Link connected to: a Transit Network
         (Link ID) Designated Router address: 10.0.45.3
         (Link Data) Router Interface address: 10.0.45.3
          Number of TOS metrics: 0
           TOS 0 Metrics: 10

        Link connected to: a Transit Network
         (Link ID) Designated Router address: 10.0.123.4
         (Link Data) Router Interface address: 10.0.123.3
          Number of TOS metrics: 0
           TOS 0 Metrics: 30

        Link connected to: another Router (point-to-point)
         (Link ID) Neighboring Router ID: 5.5.5.5
         (Link Data) Router Interface address: 10.0.35.3
          Number of TOS metrics: 0
           TOS 0 Metrics: 5

        Link connected to: a Stub Network
         (Link ID) Network/subnet number: 10.0.35.0
         (Link Data) Network Mask: 255.255.255.0
          Number of TOS metrics: 0
           TOS 0 Metrics: 5

        Link connected to: another Router (point-to-point)
         (Link ID) Neighboring Router ID: 4.4.4.4
         (Link Data) Router Interface address: 10.0.34.3
          Number of TOS metrics: 0
           TOS 0 Metrics: 15

        Link connected to: a Stub Network
         (Link ID) Network/subnet number: 10.0.34.0
         (Link Data) Network Mask: 255.255.255.0
          Number of TOS metrics: 0
           TOS 0 Metrics: 15

    ================

    R6#   show ip ospf database network 10.0.123.1

                OSPF Router with ID (6.6.6.6) (Process ID 1)

            Net Link States (Area 0)

      LS age: 49
      Options: (No TOS-capability, DC)
      LS Type: Network Links
      Link State ID: 10.0.123.1 (address of Designated Router)
      Advertising Router: 1.1.1.1

      LS Seq Number: 80000002
      Checksum: 0x4B33
      Length: 40
      Network Mask: /32
        Attached Router: 1.1.1.1
        Attached Router: 2.2.2.2
        Attached Router: 3.3.3.3
        Attached Router: 4.4.4.4

     

     

     

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