[c-nsp] OSPF design

[Robert Crowe (rocrowe)]

There are many different reasons and topologies where MPLS can be
extended to the access layer depending on technical and non-technical
requirements. Perhaps Rin can elaborate on his topology and what he is
trying to achieve, as it was not delved into in the previous email. The
point that I was making was that summarization at the OSPF ABR is
possible when running MPLS services and is widely used. Just remember
that you cannot summarize (today) your main Loopback used for your
LDP/BGP ID as there needs to be a full LSP from ingress-to-egress PE
across areas, if you providing L2/L3VPN services.

 

Robert Crowe

Email: rocrowe at cisco.com

 

From: Mack O'Brian [mailto:mackobrian40 at gmail.com] 
Sent: Friday, October 22, 2010 11:39 AM
To: Robert Crowe (rocrowe)
Cc: Rin; cisco-nsp at puck.nether.net
Subject: Re: [c-nsp] OSPF design

 

So what is main reason of carrying MPLS all the way into your
access-layer?



 

On Fri, Oct 22, 2010 at 6:37 AM, Robert Crowe (rocrowe)
<rocrowe at cisco.com> wrote:

You can summarize at ABR's, just don't summarize your main
Loopback/LDP-ID/BGP-ID range.

Robert Crowe
Email: rocrowe at cisco.com

-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net
[mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Rin
Sent: Friday, October 22, 2010 8:25 AM
To: cisco-nsp at puck.nether.net
Subject: [c-nsp] OSPF design

Hi group,



We need to design a MPLS network that has around 100 nodes (7600)
divided into Core, Aggregation & Access layer. OSPF and MPLS is deployed
up to access layer. According to Cisco, an OSPF area should have no more
than 50 nodes in order to minimize the database. With that concept, we
should design our network into different areas, say Core & Aggregation
in Area 0, Access nodes in area 1. However, I reckon separating the
network into different OSPF areas without summarization at ABR cannot
minimize OSPF database, all routers still receive routes advertises by
other routers. If we do summarization at ABR, MPLS cannot work since
this is a continuous MPLS domain.



So my question is should we separate the network into different OSPF
areas as Cisco recommendation or should we keep all routers in an OSPF
area 0?
Note that we intend to provide MPLS L2VPN, L3VPN on this network; we can
only use OSPF, ISIS is not an option.



Thanks,

Rin



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