Re: [Idr] Discussions about RT-Constrain //RE: IETF-78 IDR minutes

Hello Zhenqiang,

Many thx for your email. I have no doubt about your deployment case. In 
fact I think what you are planning to do does make sense.

But let's do not forget about the overall picture. RT-constrain's 
primary objective was to help automate inter-as VPNs. Later we have 
observed that it may also help to allow to store on RRs only those set 
of routes which are desired. The fact that it allows limit the amount of 
automated inbound filtering on the PEs is more or less the over all 
positive side effect :)

So RT-constrain in itself is an optimization. This draft would be an 
optimization to the optimization.

Reg the impact of IPv6 introduction how many VPN IPv6 routes are you 
concerned with ? Note that there are production IPv4 deployments with 
over 1 million IPv4 routes today and without rt-constrain deployed at all.

Are you concerned with the need to drop unnecessary routes on inbound RR 
-> PE (which is a very cheap operation) on those PEs which do not need 
them ? Or are you under impression that all PEs would need to store 
those routes even if those would not be needed .. the latter would be 
very easy to address without any protocol changes by your favorite BGP 
implementation.

Many thx,
R.

> Hi Robert and Jie,
>
> I am Zhenqiang Li from China Mobile. I think this draft is useful. We
> are now planning the IPv6 migration scheme. During the migration
> period, some sites of a specific service will introduce IPv6 first.
> These IPv6-enabled sites (still support IPv4) need to communicate
> with other sites belonging to this specific service, including both
> IPv6-enabled and IPv4-only sites. Because they are parts of one
> service, we want them to be in one VPN. Thus we give the IPv6 route
> the same RT as the IPv4 route of this service. By using the proposed
> scheme in this draft, we can control the IPv6 route distribution
> within the IPv6-enabled sites. This is also helpful to limit the
> potential impact of IPv6 introduction.
>
> Best Regards, Zhenqiang Li
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