Routing

Expand all | Collapse all

OSPF overload configuration

Jump to Best Answer
  • 1.  OSPF overload configuration

    Posted 20 days ago
    I have the following diagram

    I tried to configure overload on vMX5 to force outbound traffic via vMX2 from vMX8. Can I do this ?

    I did some tests and did not work. not sure whether caused by my poor image or something I missed.

    thanks !!


  • 2.  RE: OSPF overload configuration

    Posted 20 days ago
    I did more tests and noticed it might be caused by NSSA.  After I removed NSSA,  it works.

    Anyone can coach me why overload does not work for NSSA.


  • 3.  RE: OSPF overload configuration
    Best Answer

     
    Posted 19 days ago

    Hi, 

    OSPF overload causes LSAs advertised by the router to set its metrics to 65535 (max metric).
    In the NSSA it would depend on NSSA configuration whether summaries  or default-lsa is generated by ABR and sent into NSSA.

    If summaries are allowed, then max-metric is set.

    Example:

    Summary  1.1.1.1          1.1.1.5          0x80000002   126  0x20 0x41f0  28
      mask 255.255.255.255
      Topology default (ID 0) -> Metric: 65535
      Aging timer 00:57:54
      Installed 00:02:05 ago, expires in 00:57:54, sent 00:02:03 ago
      Last changed 00:02:05 ago, Change count: 2


    If no-summaries and only default-lsa is sent into NSSA generated by ABR, then overload max-metric will not be set, as the default-metric is a static value.
    On vmx5/8, the metrics can be verified:

    show ospf database area 2 advertising-router <router-id-vmx5> extensive


    Cheers,



    ------------------------------
    Ashvin
    ------------------------------



  • 4.  RE: OSPF overload configuration

    Posted 19 days ago
    thanks so much for your insights !