Re: OSPF: Stub Area vs Stub Network

It's easy to get confused :)

Stub Router
Stub Area
Stub Network

Any more?

On Mon, Dec 14, 2009 at 9:04 AM, karim jamali <karim.jamali_at_gmail.com>wrote:

> 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/>
>>
>
>
>
> --
> KJ
>

-- 
Bryan Bartik
CCIE #23707 (R&S, SP), CCNP
Sr. Support Engineer - IPexpert, Inc.
URL: http://www.IPexpert.com
Blogs and organic groups at http://www.ccie.net