Le 20 nov. 2009 à 07:40, Jan Melen a écrit : > Hi, > > On Nov 19, 2009, at 11:06 AM, Rémi Després wrote: > >> >> Le 18 nov. 09 à 23:50, William Herrin a écrit : >> >>> *AND* if D is a complex network instead of a simple router, that >>> complex network needs a *dynamic routing protocol* that helps the >>> routers in D do the right thing, not just static policy routing. >> >> In a complex D, an alternative to a dynamic routing protocol consists in a stateless address mapping, in border hosts and routers of D, with encapsulation of global packets to traverse D. >> >> This is feasible with the SAM approach described in draft-despres-softwire-mesh-sam-01. >> A customer-side border node, when it has to forward a global packet toward the global Internet, selects the destination of the encapsulating header based on which PA prefix it finds in the source global address. This destination is the address of the provider-side border router to which this PA prefix has been delegated (known by some parameters received in DHCP ). >> >> If you have a look at this draft, maybe you can tell whether you agree or not on the relationship with the point you make. >> > > Remi could you elaborate a bit more why would we need a encapsulation inside D to solve the routing problem? Thanks to encapsulation, an end-to-end packet can be routed across a local routing domain with a forced local destination. This one can depend on which ISP delegated to the domain the prefix matched by the E2E source address. > Why don't we use existing routing protocols instead to exchange the information and even do DFZ routes inside D as was pointed out earlier? Note that nodes that support a dynamic routing protocol compatible with one supported by their ISPs don't *need* SAM. It is just an alternative. In favor of SAM is its simplicity (no protocol, no AS number...). > I don't think we want to introduce something like SAM in to the end-hosts for doing this and I'm not even convinced that we need for D either? In multihomed sites having several CPEs, a host that supports neither a routing protocol nor SAM cannot ensure that a packet it sends send goes to the right ISP (that which provided the PA prefix matched by the source address). RD
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