Re: OSPF: Stub Area vs Stub Network

Bryan,

Yeah I do understand clearly what you are saying..I thought that the stub
network is not by itself a feature and is common to all routing protocols,
and is not specific to OSPF. You are right, I explained the differences
between the Stub Router Feature & Stub Areas because usually this is where
the confusion occurs.

Thank You for your clarification.

Best Regards,

On Mon, Dec 14, 2009 at 5:54 PM, Bryan Bartik <bbartik_at_ipexpert.com> wrote:

> Karim,
>
> That link is to the Stub Router feature. Stub Network is a link that is not
> used to reach any other networks, not necessarily one with a max metric.
> Basically a link that has no other routers on the other end. For example, a
> loopback will show up in the OSPF database as a stub network:
>
> R1#sho ip osp database router 1.1.1.1
>
> OSPF Router with ID (1.1.1.1) (Process ID 1)
>
> Router Link States (Area 0)
>
> LS age: 18
> Options: (No TOS-capability, DC)
> LS Type: Router Links
> Link State ID: 1.1.1.1
> Advertising Router: 1.1.1.1
> LS Seq Number: 80000002
> Checksum: 0xD639
> Length: 48
> Area Border Router
> Number of Links: 2
>
> Link connected to: a Stub Network
> (Link ID) Network/subnet number: 1.1.1.1
> (Link Data) Network Mask: 255.255.255.255
> Number of TOS metrics: 0
> TOS 0 Metrics: 1
>
> Stub Network is a type of the Router LSA (type 1). The types are
>
> 1 Point-to-point connection to another router
> 2 Connection to a transit network
> 3 Connection to a stub network
> 4 Virtual link
>
> See RFC 2328 Appendix (Section A.4.2) for more details.
>
>
>
> On Mon, Dec 14, 2009 at 7:55 AM, karim jamali <karim.jamali_at_gmail.com>wrote:
>
>> 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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>
> --
> Bryan Bartik
> CCIE #23707 (R&S, SP), CCNP
> Sr. Support Engineer - IPexpert, Inc.
> URL: http://www.IPexpert.com <http://www.ipexpert.com/>
>

-- 
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