Tuesday 27 November 2007

OSPF and NBMA Networks

Confused about which NBMA network type requires a DR/BDR or neighbours to be statically defined? Worry no longer..............................

If the keyword nonbroadcast is within the network type (i.e. ip ospf network non-broadcast, or ip ospf network point-to-multipoint non-broadcast) then neighbours must be defined.

If the keyword point is within the network type (i.e. ip ospf network point-to-point, ip ospf network point-to-multipoint, ip ospf network point-to-multipoint non-broadcast) then a DR/BDR is NOT elected.

You may see a question which has an output showing the network type as point-to-multipoint. It will then ask you to choose a couple of correct answers. From above we know the answer to be that DR/BDR are not elected and neighbours do not need to be statically defined.

HTH!
at

2 comments:

  1. Unknown22 October 2008 at 01:37

    Chris,

    in both cases where you determine if a DR/BDR is NOT elected or neighbourz must be defined you have the example:

    ip ospf network point-to-multipoint non-broadcast

    Is there a typo anywhere?

    Peter

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  2. Unknown3 February 2013 at 16:57

    Hi, can you help me with this;
    Determine the summary address and the mask to be used that will summarize the subnet 172.148.0.0/13 through 172.156.0.0/13
    Explanations will be appreciated.
    Thanks

    ReplyDelete