On Fri, Jul 11, 2014 at 09:24:21AM +0000, Scharf, Michael (Michael) wrote: > > 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.
In this use case, would you really have a full(!) 5000x5000 matrix? Or would it be more like a sparse matrix, defining cost only for 5000 branch offices X 100 data centers, while most (all?) other costs (i.e., branch office to branch office) are "default"? Thanks, Sebastian _______________________________________________ alto mailing list [email protected] https://www.ietf.org/mailman/listinfo/alto
