"Cisco MPLS-based VPNs" & BGP Stability

Robert Raszuk raszuk at cisco.com
Wed Apr 18 08:38:33 UTC 2001

Hi Danny,

> I'm referring more to the PE impact, or any other router that
> participates in unicast IPv4 peering.  There's still a single
> BGP process, a finite amount of memory and CPU resources, etc..,
> and impacting any of these can adversely effect IPv4 route
> stability.

But that was my point if you have a few vpnvs hang on any given PE with
a few thousand of routes I don't think even ipv4 peering PE will fell
any impact. On the other hand when your number of vpnv4 routes grow on
PE it is clear that with current hardware limitations (mostly memory, a
bit of CPU) operator will need to decomposition ipv4 nodes from vpn PEs
hence the PEs will have 0 impact to the ipv4 BGP stability. 

> I fully agree that if dedicated infrastructure is employed for
> this purpose then there will clearly be less impact.  However,
> the whole pitch is that existing network elements can be used
> to offer the service, the same network elements that provide
> "Internet" connectivity today -- and lots of folks have drank
> the kool-aide -- all in hopes of generating more revenue from
> their existing IP infrastructure, not new dedicated or overlay
> ones.

As I said above you don't until you need to dedicate boxes for
mpls-vpns. When you have so many customers that don't simply fit into PE
(already loaded with 90K of ipv4 routes) you have two choices: 

A) Buy a more powerfull box,
B) Decomposition Internet and VPN 

> Then every time someone brings up a scalability or convergence
> or security issue with BGP/MPLS VPNs a slew of Cisco folks tell
> them it's targeted at private networks and different
> infrastructures (hence the requirement for BGP, MPLS, etc..,
> I guess).
> Rob, I know how you & your cohorts feel, I was looking for operator
> feedback.  

No it is not that I am feeling one way or the other. Getting feedback is
extremely usefull - but all I care about it to get feedback regarding
true issues not those which are practically not the problem.

> -danny (who strives to only listen to the rest of this thread)

I will do the same letting other's comment.


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