The MPLS-OPS Archive

[Danny McPherson <danny@ambernetworks.com>]

> certainly enough to satisfy the VPN requirements of the SP.

And what requirements would that be?

> the existing IPv4 sessions can carry VPNv4 NLRI as well as IPv4 and the 
> route reflectors can reflect IPv4 and VPNv4 prefixes.

But the point here is that the core devices with [concave 
cluster architectures] are typically the RRs or ASBRS and 
they don't see the VPN AFs so overlay RR topologies are now
required.
 
> this depends on how you deploy it - sure, you can use different route 
> reflectors for VPNv4 but you can also use existing IPv4 route reflectors. 

Then you have lots VPN routing state in the core (yeah, I know, not 
forwarding state).

> which topologies exactly do you mean ? there are many different topologies 
> and ways to deploy BGP.

The ones that removes the VPN route state from the core.

> 
> >   o you really don't know if the route was processed by the
> >     target PEs, just that your peer acknowledged receiving the
> >     segments.
> 
> this is not an argument as TCP has always assumed that the receiving peer 
> has processed the data through receipt of an acknowledgement.

Yeah, but if I give it to a 'third party' VPN AF route reflector 
I have no idea if it was passed along to the target client.

> so could mis-configuration of your IP routing structure so 
> I do not see how this is any different.

It's more complex, which increase error probability.

> I would class MPLS/VPN in this category - what specific solution do you 
> have in mind ?

Oh, I don't know.  Anything that coupled an IP encapsulation 
mechanism with a signaling protocol.  L2TP or the like, perhaps.
 
> >   o a NMS to configure and manage the edge devices
> >   o employ whatever transport substrate (e.g., MPLS, IP
> >     for edge-to-edge) folks wanted to use
> 
> this is also possible with MPLS/VPN - you do not have to run MPLS in the 
> backbone if you would prefer to run GRE tunnels or some other type of 
> encapsulation mechanism.. Jim

Yeah, MPLS in GRE to get over an IP core.  That makes a heck of a 
lot of sense with the initial problem could have been solved with 
IP alone, then employed the interesing MPLS benefits such as TE 
-- if need be.

-danny



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