Subject: Re: draft-ietf-ospf-multi-area-adj-03.txt

From: SUBSCRIBE OSPF vishnuvardhan B <[email-masked]>
Date: Thu, 10 Mar 2005 10:15:53 -0500

Hi Ace,
Thanks for the reply. I have some more scenarios:
1) I am trying to configure a secondary adjacency on a broadcast link.
In this scenario should the secondary form full mesh(adjacency) with all
the neighbors on the broadcast link?
2) One more question before configuring a secondary on a router the router
should be an ABR or after configuring should it become ABR?
Thanks&Regards,
Vishnu

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From: Acee Lindem <[email-masked]>
Date: Thu, 10 Mar 2005 10:38:08 -0500

Hi Vishnu,

>the neighbors on the broadcast link?
This solution requires the configuration of a secondary adjacency with 
each neighbor
on the broadcast link .There are other possible solutions but this 
approach has made the trade-off
in favor of simplicity. .

>should be an ABR or after configuring should it become ABR?
It is assumed that the two routers are ABRs. However, the secondary 
adjacency is completely
decoupled from the primary adjacency. Hence, there is nothing in the 
draft that precludes two
non-ABRs from forming a secondary adjacency.

Hope this helps,
Acee

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From: Ramanan N <[email-masked]>
Date: Thu, 17 Mar 2005 16:38:00 -0500

Hi Acee 

> non-ABRs from forming a secondary adjacency.

Does this mean that for the topology,
R5 is a ABR in area A0 & A1. R1, R2, R3, R4 are in area A1.

R1------------R2------------R3------------R4-----------area1--R5--area0 

now, if R2 & R3 form a multi area link between them with A0 as the
secondary area,
then do R2 and R3 really become ABR routers although they are intra area routers
of area A1 ?

Regards
Ramanan

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From: Acee Lindem <[email-masked]>
Date: Thu, 17 Mar 2005 16:54:10 -0500

>then do R2 and R3 really become ABR routers although they are intra area routers
Hi Ramanan,
This draft does not change the fact that neighbors must be attached to 
the same
link (i.e., this is not like a virtual link). Hence, in the topology 
above, R5 could not
be a nieghbor or R2 and R3. However, if you meant R1-R5 to be on the 
same LAN
then R2 and R3 would not become ABRs just because they have secondary
adjacencies.
Thanks,
Acee

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From: Ramanan N <[email-masked]>
Date: Fri, 18 Mar 2005 00:27:18 -0500

> then R2 and R3 would not become ABRs just because they have secondary

Hi Acee,

I have two questions here, 

1. If the routers were in LAN then on what criteria should the routers
R2 & R3 be
prevented from not becoming ABR, because after the multi area configuration, 
both R2 and R3 would have 
   a. two interfaces (one being the physical and other being the
secondary topological link)
       in different areas and fully adajacent neighbors too.
   b. backbone connectivity in the secondary topological link

2. In case the routers were to be in P2P connection in the above topology, 
then can routers R2 and R3 become ABRs ?

Regards
Ramanan

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From: Acee Lindem <[email-masked]>
Date: Fri, 18 Mar 2005 08:53:50 -0500

Hi Ramanan,

If they are also connected to R1 in another area over the same link they 
will become ABRs.
You didn't state that in your previous list post. A secondary adjacency 
is NO different from an
adjacency on an unnumbered point-to-point link (as stated in the draft). 
If you think of it in
that manner all your questions should be answered.

Thanks,
Acee

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From: Ramanan N <[email-masked]>
Date: Fri, 18 Mar 2005 12:17:45 -0500

Hi Acee,

Let me reframe my initial question for more clarity.

Routers R1 and R2 are connected by single physical link in area 0.
if multi area adjacency is enabled between R1 and R2 in this physical link 
in the secondary area 1, should routers R1 and R2 attain ABR status ?

Regards
Ramanan

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From: Acee Lindem <[email-masked]>
Date: Fri, 18 Mar 2005 12:29:15 -0500

>in the secondary area 1, should routers R1 and R2 attain ABR status ?
Of course, they're now connected to 2 areas.