Re: [Ila] [5gangip] Scaling mapping systems (was Re: BOF Description)

[Dino Farinacci <[e-mail]>]

> In ILAMP (https://tools.ietf.org/html/draft-herbert-ila-ilamp-00) secure redirects are defined to be the primary means of populating a cache. On a cache miss, a packet is forwarded into the network and routing should forward the packet to an ILA router that contains the complete set of mappings for the

In LISP, we have PITRs that do roughly the same thing. But it comes at an expense that EIDs need to be advertised into the core routing system. I guess in your case, it is on the SIR-prefix that is injected and a packet destined for any ID with a SIR-prefix goes to the closest ILA router. Is that right?

> associated shard. The router performs the transformation and can send a redirect back to the caching node. The redirect can be cached so that subsequent packets take a direct route and avoid the

But you will get some out of order packets. Until the cache is populated, packets are still in the network, either packets that have not reached the ILA router, or packets that have been transformed. So if the ILA router near the source, or the source itself, sends directly, there is a chance it is a shorter path. So new packets arrive to the destination before packets in flight.

> trianglular routing. Redirects must be secure so that they cannot be spoofed, so for that reason (and some others) the protocol is over TCP. The mapping cache is only an optimization and packets are never dropped or queued for pending cache resolution. If the cache weren't present, communications would

But the ILA router in the network needs to have the mapping. And if it does not, what happens then?

> still be viable but sub-optimal; that characteristic establishes a bound for the worst case DOS attack.
> 
> Any thoughs on this approach?

You’ll really need to put signatures in the Redirect messages if you want robust authentication.

Dino