[c-nsp] ISP / MPLS "POP" design

[CiscoNSP List]

Hi,

Have a couple more questions on this :)

1. I notice that a number of people use IS-IS rather than OSPF - Is there benefits to using one vs the other?

2. Majority of customer tails will be supplied via vlans (On Carrier AGG's) - Typically we would have two AGG's from two different carriers per POP. I was looking at using 2 x 4948's to terminate the Carrier AGG's (Trunk ports), then trunk ports to the 7200's(PE's) for L3Any recommendations/advice on how to provide redundancy for these customer tails?
i.e.
Carrier A AGG to 4948(A)
Carrier B AGG to 4948(B)

4948(A) then has trunk links to both 7200(PE A) and 7200(PE B), and same with 4948(B) - Is an acceptable setup to have Carrier A L3 Ints on 7200(A) and Carrier B L3 Ints on 7200(B), and then if we were to lose (for example) 7200(A) we trunk Carrier A's vlans to 7200(B) and create the dot1Q Ints to restore service? 

Thanks in advance for any feedback/advice.


 
> 
> > From: mark.tinka at seacom.mu
> > To: cisconsp_list at hotmail.com
> > Subject: Re: [c-nsp] ISP / MPLS "POP" design
> > Date: Thu, 31 Oct 2013 04:06:27 +0200
> > CC: cisco-nsp at puck.nether.net
> > 
> > On Wednesday, October 30, 2013 11:35:59 PM CiscoNSP List 
> > wrote:
> > 
> > > Thanks Mark.
> > > 
> > > So to clarify - If I run 2 (7201's) as RR's, they would
> > > take the full tables from the IPTransit 7200's(POPA),
> > > plus all customer global IP's, plus all VPNv4
> > > routes(From POPA+B+C)?
> > 
> > That's right.
> > 
> > The 7201's CPU is very capable. It tops out at 2GB of RAM, 
> > and should be able to handle your current deployment just 
> > fine.
> > 
> > > If that's the case - Do you filter what routes the RR's
> > > advertise to RR clients?  i.e. POPA has the 2 7200's
> > > with IPTransit full table, do the RR's advertise the
> > > full table to the 7200's at POPB + C?
> > 
> > That's a design decision.
> > 
> > Some operators don't filter in iBGP, ensuring every router 
> > has, pretty much, the same view of the state of BGP in the 
> > core.
> > 
> > Other operators, like myself, implement network-wide routing 
> > policy in iBGP, which is easiest done in the route 
> > reflectors, as that is how different routers performing 
> > different functions learn (which) routes (they should be 
> > receiving).
> > 
> > If you're not sure what to do, go simple and evolve the 
> > configuration as your network does so.
> > 
> > Cheers,
> > 
> > Mark.
>  		 	   		  
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