Re: EIGRP+PPP

Could you guys be any older :) Hehehe! Narbik, is that really your CCIE # or is it your Social Security Number!

Jokes aside, that was great! Thanks Narbik!

Sent from my iPad

On Sep 1, 2010, at 6:19 PM, Robert Hosford <rhosford_at_certifiednets.com> wrote:

> Narbik,
>
> This post is an excellent example the little gotchas you can learn here. When ISDN was on the lab this was one of the issues you had to know cold. So thank you for the trip down memory lane.
>
> Robert
>
> -----Original Message-----
> From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On Behalf Of Narbik Kocharians
> Sent: Wednesday, September 01, 2010 5:54 PM
> To: Marcelo Rosa
> Cc: karim jamali; masroor ali; Cisco certification
> Subject: Re: EIGRP+PPP
>
> Just to add to whats being said here.
>
> This behaviour was useful from the days when we used Modems to connect to the Internet (My grandma's days). You needed to know how to connect to the pop router and it needed to know how to connect to you. So you had to run PPP.
>
> Nowadays, we use this behavior to provide reachability, since PPP adds neighbor's IP address as a host route in your routing table the end points no longer need to be in the same subnet to have NLRI to each other.
>
> Why remove it?
> Going back to Rocky Marciano days, when we had ISDN and we needed to use the ISDN link as a backup to a frame or other types of links. The second you did an "Encap ppp" under your BRI interface, ppp added the /32 host routes automatically (Default behaviour), now....let's say you are running OSPF over the main and your ISDN interfaces, we both know that OSPF's hellos will keep the ISDN link UP, unless you do an "IP OSPF DEMAND-CIR" under your BRI interface, which maintained the OSPF neighbor adjacency while bringing the ISDN link down, the ONLY time the ISDN link would ever come up is when OSPF detected a topology change. If you did not do this, end of the month you would get a bill for few thousand dollars for your ISDN usage. An RGE event (Resume Generated Event).
>
> But once OSPF establishes a nieghbor adjacency through the ISDN link and brings the ISDN link down, from PPP's perspective, the link was down so it removed the /32 route. Once the route was removed, from OSPF's perspective we had a topology change, so OSPF will bring the link back up to convey the changes, and the cycle repeated itself, so the end result was that the ISDN link kept on flapping. So what we had to do was to remove the host route by configuring "No peer neighbor-route".
>
> I hope this helped.
>
> On Wed, Sep 1, 2010 at 2:02 PM, Marcelo Rosa <MRosa_at_multirede.com.br> wrote:
>
>> These /32 routes exist to address the issue when you use ip unumbered
>> and the borrowed ip addresses are not in the same subnet. As Karim
>> stated, they make reachability possible. I you don4t need it, you can
>> use the no peer neighbor-route to eliminate it.
>>
>> HTH,
>>
>>
>> Marcelo Rosa
>> http://codornafatiada.wordpress.com
>> http://projectccie.wordpress.com
>> Sent from my Ollivetti Lettera 82
>>
>> "It4s supposed to be hard. If it wasn4t hard everyone would do it. The
>> hard is what makes it great."
>>
>>
>>
>> -----Mensagem original-----
>> De: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] Em nome de
>> karim jamali Enviada em: quarta-feira, 1 de setembro de 2010 17:57
>> Para: masroor ali; Cisco certification
>> Assunto: Re: EIGRP+PPP
>>
>> Dear Masroor,
>>
>> This has nothing to do with EIGRP. Just run PPP on both sides of the
>> interface and you will see that peer neighbor route will always
>> install the host route for the other side. This is PPP's normal
>> behavior, well I kind of think about it "it is just 2 people on the
>> link" so they must be able to reach each other. You can also try it
>> with different subnets (1.1.1.1 and
>> 3.3.3.3) for instance and you will see that the peer neighbor route
>> makes reachability possible.
>>
>> HTH,
>>
>> Best Regards,
>>
>> On Wed, Sep 1, 2010 at 11:46 PM, masroor ali <masror.ali_at_gmail.com> wrote:
>>
>>> can you please describe more???
>>>
>>> On Thu, Sep 2, 2010 at 1:44 AM, rajeevan singh
>>> <rajeevansingh_at_gmail.com
>>>> wrote:
>>>
>>>> so no peer neighbor-route , on the link ( interface.)
>>>>
>>>> On Thu, Sep 2, 2010 at 2:12 AM, masroor ali <masror.ali_at_gmail.com>
>>> wrote:
>>>>
>>>>> hi,
>>>>>
>>>>> when using ppp with eigrp, why it shows /32 neighbor route in
>>>>> local routing table??? and using no peer neighbor-route it
>>>>> doesnt show /32 route what's the idea?
>>>>>
>>>>> --
>>>>> Regards,
>>>>> Masroor Ali
>>>>>
>>>>>
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>>>
>>>
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>>> Regards,
>>> Masroor Ali
>>>
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>>
>> --
>> KJ
>>
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>
>
> --
> Narbik Kocharians
> CCSI#30832, CCIE# 12410 (R&S, SP, Security) www.MicronicsTraining.com Sr. Technical Instructor YES! We take Cisco Learning Credits!
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Received on Wed Sep 01 2010 - 18:31:44 ART