[c-nsp] MPLS - MP-BPG with multiple OSPF areas

[Vitkovsky, Adam]

Hi 
The suppression won't fix this behavior but will reduce the number of prefixes ospf needs to carry to roughly 200 -thus enabling you to use a single area 0
I'd recommend not to use multiple areas within the same AS (or confed member-as) as there are mpls features which needs some tweaking when used in inter area environments -it's enough to deal with these in inter-as solutions :)

adam
 
-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Livio Zanol Puppim
Sent: Wednesday, October 19, 2011 11:53 AM
To: David Prall
Cc: cisco-nsp at puck.nether.net
Subject: Re: [c-nsp] MPLS - MP-BPG with multiple OSPF areas

You're right David. There are out of order no packets, only asynchronous
traffic. Sorry about that...

I don't think that only the supression would do the job, since the loopbacks
will still be in different areas.

2011/10/18 David Prall <dcp at dcptech.com>

> Livio,
> Where are you getting out of order packets? You do have asymmetric hop
> counts, which most likely means asymmetric latency. But all the packets
> should be in order. Could use DWDM so that each router isn't directly
> connected and everything looks the same number of hops away, of course more
> ports are required at the Area 10 edge.
>
> You can use prefix-suppression to only advertise the loopback using OSPF,
> to
> minimize the number of LSA's. Then use MPLS and BGP for all packet
> forwarding, including the global table.
>
> David
>
> --
> http://dcp.dcptech.com
>
>
> > -----Original Message-----
> > From: cisco-nsp-bounces at puck.nether.net [mailto:cisco-nsp-
> > bounces at puck.nether.net] On Behalf Of Livio Zanol Puppim
> > Sent: Tuesday, October 18, 2011 9:34 PM
> > To: cisco-nsp at puck.nether.net
> > Subject: [c-nsp] MPLS - MP-BPG with multiple OSPF areas
> >
> > Hello everybody,
> >
> > I have a doubt with a lab design that we are creating to test some MPLS
> > topologies. I would like to know if anybody can help me solve a problem
> > that
> > I am facing about routing paths. To help ilustrate the topology I'm
> > sending
> > the image link below.
> >
> > https://docs.google.com/leaf?id=0B4Hf34G524HsNTA3ZTc1NTItNmJlNi00ZDQyLW
> > I1ZDAtYTg5MTliODRjMDhk&hl=en_US
> >
> > In the topology, I have two core routers interconnected with a 1 Gbps
> > link
> > and several other routers interconnected with a 100Mbps link. The
> > interfaces
> > between the core routers are in the OSPF area 0 and all other physical
> > interfaces are in the OSPF area 10. Each one of the two core routers
> > also
> > have a connection to the area 10 using a 100Mbps interface.
> >
> > The router ID and the "update-source interface", on the core routers
> > (PE1)
> > is a loopback interface that belongs to the OSPF area 0.
> > The router ID and the "update-source interface", on the access routers
> > (PE6)
> > is a loopback interface that belongs to the OSPF area 10.
> >
> > After establishing OSPF adjacencies between all routers, the BGP
> > process
> > starts to establish connection, and this undesirable behavior happens:
> >
> > When the router PE1 (area 0) wants to establish a BGP session with
> > router
> > PE6 (area 10), the packet flow through all 100Mbps (purple arrow). When
> > the
> > router PE6 (area 10) responds, the packet flow through the 1Gbps
> > connection
> > between the core routers (red arrow). Every flow that needs to use the
> > LSPs
> > will do logically the same, causing out-of-order packets at the
> > network.
> >
> > I know that this is an expected behavior, as intra-area routes are
> > preferred
> > over inter-area routes, no matter what the link cost is.
> >
> > The question is: What solution do you guys think it's better for this
> > scenario, so that the packet flow goes always through the optimal path?
> > - Sham-links;
> > - Extended area 0 to one more hop;
> > - Change the "update-source interface" for area 10;
> > - Create small areas between the core and access routers
> > - Other solutions...
> >
> > We are planning to deploy a network with more than 200 PE routers in a
> > similar scenario, and I don't think that a single OSPF area is a good
> > choice
> > for us.
> >
> > Can anybody help with some advice?
> >
> > --
> > []'s
> >
> > Lívio Zanol Puppim
> > _______________________________________________
> > cisco-nsp mailing list  cisco-nsp at puck.nether.net
> > https://puck.nether.net/mailman/listinfo/cisco-nsp
> > archive at http://puck.nether.net/pipermail/cisco-nsp/
>
>


-- 
[]'s

Lívio Zanol Puppim
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