Forum Replies

  1. Hi Rene

    I have a couple of questions. Why this is sent as a Type 5 LSA even when the R1 and R2 routers are in same area. I guess since this is a Type 5 LSA it shows as an O*E2 ( External with Metric 2, so the actual cost of R1 to R2)


  2. jeff says:

    Type 5 – External LSA: also known as autonomous system external LSA: The external LSAs are generated by the ASBR.

    When you generate a default route. You are advertising a route that looks like it from another network. In the example the default route could represent the ISP connection. R1 would represent the ASBR and generate type 5 LSAs (default route).

    Hope this helped to answer your question.

  3. Hi Sims,

    Let's say you have a small network with a couple of routers. One router is connected to an ISP router for Internet access. On this router, you could advertise a default route in your OSPF network.

    When there is no matching route in the routing table, the default route will be used and your traffic will be forwarded towards the ISP.


  4. If you have a DMVPN network and a spoke is receiving a bunch of OSPF routes, along with default route (default-info originate), but don't want a default route, but can't change that default-information originate command on the hub, can you use some sort of route map or prefix list that you could configure on the spoke to block the default route being advertised?

    I hope this makes sense..

  5. andrew says:

    Yes, you can do this, sort of :slight_smile:

    Remember that a requirement for OSPF is that all members in the same area must have identical databases (and I presume that your DMVPN hub and spokes are in the same area). So the best you are going to be able to do is keep that default route from getting installed in the routing table, even though it will still be present in the OSPF database. I recommend using a prefix-list to do it. Here's a sample:

    (config)#ip prefix-list PL_NODEFAULT deny
    (config)#ip prefix-list PL_NODEFAULT permit le 32
    (config)#router ospf 1
    (config-router)#distribute-list prefix PL_NODEFAULT in

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