Re: OSPF: Stub Area vs Stub Network

Hi Syed,

A stub network in OSPF occurs when the router advertises all its
non-originated LSAs with a maximum metric, i.e. usually when the router
needs to reload or go off the network so that the router will stop to be a
transit path for non-locally originated networks..The command used is
*max-metric
router-lsa *under the OSPF process. There are various options that can be
used with this command. The most common ones are using a timer (when this
timer ends) the router will advertise those routes with a normal metric. A
maximum metric for all non locally originated LSAs is advertised with
maximum metric. You can configure it to keep advertising routes (LSAs) with
maximum metric until BGP converges and then back to regular metrics.

To read more about this feature:
http://www.cisco.com/en/US/docs/ios/12_2t/12_2t4/feature/guide/ftospfau.html

A stub area is a completely different concept. An area in OSPF can be
defined to be stub i.e it will block LSA 4(Who redistributed the routes) &
LSA 5(External Routes). All the routers in the area must agree on the stub
flag to be neighbors. It is the ABR that does the filtering as routes are
injected into the area.You can refer to this document for more information:

http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094aaa.shtml#definestub

Best Regards,

Karim

On Mon, Dec 14, 2009 at 12:40 PM, Syed Khalid Ali <
khalid_khursheed_at_hotmail.com> wrote:

> Dear Group:
> Can any one explain the difference between two?
> regards,Khalid
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KJ
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