> On Wed, Jul 09, 2014 at 03:14:56PM -0400, Wendy Roome wrote: > > As for the second point, incremental update is only necessary for > large > > maps. If a map only has 25 PIDs, why bother? Just download a new > version. > > What do I mean by "large"? A Network Map with 5,000 PIDs, 250,000 > > prefixes, and up to 25,000,000 cost points. > > A full 5000x5000 cost map would be in the order of 130 MB gzipped json > (see "The size of the cost map" thread on the ALTO list Fri, 22 Mar > 2013). > > do we have any idea whether 5000 PIDs is a realistic assumption for > foreseeable deployments?
Indeed, 5000 seems like an extreme case. Yet, I think one could really end up there, depending on how ALTO is used. For instance, let's assume an ALTO use case like draft-scharf-alto-vpn-service for a large enterprise with many branches. As argued in the draft, only could possibly use one PID for each VPN endpoint. In that case, 5000 is not entirely unrealistic. As a random data point, Bank of America is reported to have 5,377 branches in the US. Other large organizations (e.g., retailers) may have a similar order of magnitude of branches. A L2VPN or L3VPN could be used to interconnect such branches. Obviously, there are certain ways to reduce the network/cost size in such a scenario, e.g., by introducing a hierarchy, or by topology encoding (for cost map). Also, I doubt that an application would really require an accurate cost map entry for any given combination of PIDs. Thus, 5000 looks like a kind of worst-case scenario. Michael _______________________________________________ alto mailing list [email protected] https://www.ietf.org/mailman/listinfo/alto
