Re: OSPF address used for unnumbered interface

From: Jay Hennigan (jay@west.net)
Date: Thu Sep 12 2002 - 21:54:26 GMT-3


On Thu, 12 Sep 2002, Peng Zheng wrote:

> Hi,
>
> I saw this under OSPF FAQ.
>
> Q: Which address-wildmask pair should I use for
> assigning an unnumbered interface to an area?
>
> A: When an unnumbered interface is configured, it
> references another interface on the router. When
> enabling OSPF on the unnumbered interface, use the
> address-wildmask pair of interfaces to which the
> unnumbered interface is pointing.
>
> But I don't understand.
>
>
> for example:
>
> (e0)R1(s0)-----(s0)R2(e0)
>
> Ip of e0 on R1: 1.1.1.1/24
> ip of e0 on R2: 2.2.2.2/24
> IF both s0 use ip unnumber ethernet 0
>
> And if I want to assign s0 of R1 to area 0
>
> Which address/wildmask I should use?
> 2.2.2.2/24?

No. The network statement determines which interfaces local to the
router will participate in OSPF, and in what areas.

Presumably on s0's interface configuration you have something like:
  ip unnumbered ethernet 0

You would then use e0's address in the OSPF network statement.

    network 1.1.1.0 0.0.0.255 area 0

Similarly, R2 will have in its OSPF router configuration:

    network 2.2.2.0 0.0.0.255 area 0

Referencing loopbacks might be a better design if the scenario allows it.

-- 
Jay Hennigan - CCIE #7880 - Network Administration - jay@west.net
NetLojix Communications, Inc.  -  http://www.netlojix.com/
WestNet:  Connecting you to the planet.  805 884-6323


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