Hi Tony, In "Re: [rrg] NANOG44 session on current IP address challenges", you wrote, regarding map-encap:
> How does that reduce the table size? Many or most end-user networks have micronets (roughly equivalent to LISP EID prefixes). These are not in the global BGP routing table. Each Mapped Address Block (MAB) is advertised in the BGP routing table. Each MAB contains many (ideally thousands to millions) of micronets. MABs are required so that OITRDs (Open ITRs in the DFZ - similar to LISP Proxy Tunnel Routers) can collect packets addressed to these micronets and then tunnel the packets to the correct ETR. Without this, there would be no support for multihoming and portability for the adopters of the map-encap (really core-edge separation) scheme - so hardly anyone would adopt it. Because thousands (or perhaps millions) of end-user networks share a single MAB, this greatly reduces the size of the global BGP routing table compared to doing nothing, since without map-encap, many of those end-user networks would gain their own conventional PI space, and advertise it in the BGP system. Map-encap is not the only approach - it is one way of getting packets from ITRs to ETRs in a core-edge separation scheme. Two other methods involve forwarding, using modified DFZ routers: ETR Address Forwarding (EAF) - for IPv4 http://tools.ietf.org/html/draft-whittle-ivip4-etr-addr-forw Prefix Label Forwarding (PLF) - for IPv6 http://www.firstpr.com.au/ip/ivip/ivip6/ Unlike map-encap, these have no encapsulation or overhead or PMTUD problems. Without the PMTUD problems, the ITRs and ETRs can be simpler. Also, there is translation - Six/One Router, for IPv6 only. - Robin _______________________________________________ rrg mailing list [email protected] https://www.irtf.org/mailman/listinfo/rrg
