Subject: Re: [Softwires] BGP TE attr last call by softwires WG (2nd question)

From: Igor Bryskin <[email-masked]>
Date: Wed, 3 Sep 2008 11:46:47 -0700 (PDT)

I do like  to hear comments from other people. 
 
OSPF (and any other 
flooding based protocol) is a particularly poor basis for doing restricted 
dissemination of information.  The only way to constrain the flooding 
is to constrain the topology, which adds an additional layer of 
management overhead that is simply unnecessary.

Hi Tony,
I completely agree with you. By creating overlays I propose to do exactly what you are saying: constrain the topology only to the interested parties. This puts away the scalability concerns but raises the question how bad it is in terms of configuration effort, specifically, how difficult it is to add a new PE (a member of a subset of VPNs). I know that BGP configuration is not exactly automatic either. So how big is the difference in the configuration efforts? 
I know for a fact that some L1 network operators are interested in L1 VPN application but reluctant to deploy BGP. They do deploy for quite some time already GMPLS based control plane with OSPF-TE. Why in your opinion the multi-instance OSPF solution will not be acceptible for them?

Thanks for your input.
Igor

Igor

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From: "Tony Li" <[email-masked]>
Date: Wed, 3 Sep 2008 12:57:57 -0700

I completely agree with you. By creating overlays I propose to do exactly
what you are saying: constrain the topology only to the interested parties.
This puts away the scalability concerns but raises the question how bad it
is in terms of configuration effort, specifically, how difficult it is to
add a new PE (a member of a subset of VPNs). I know that BGP configuration
is not exactly automatic either. So how big is the difference in the
configuration efforts? 
I know for a fact that some L1 network operators are interested in L1 VPN
application but reluctant to deploy BGP. They do deploy for quite some time
already GMPLS based control plane with OSPF-TE. Why in your opinion the
multi-instance OSPF solution will not be acceptible for them? 

Providers are disinclined to have any configuration that scales linearly
with the number of VPNs.  The higher the complexity of the per-VPN
configuration, the higher the work multiplier.
 
Of course, if you really want to advocate building static tunnels for VPNs,
one has to wonder why PE's and P's are involved at all.  Push the VPN
configuration to the CPE and leave the centralized boxes out of the equation
entirely.
 
Tony