On Mar 11, 2012, at 3:15 PM, Iljitsch van Beijnum wrote: > On 11 Mar 2012, at 20:15 , Joel jaeggli wrote: > >>> The IETF and IRTF have looked at the routing scalability issue for a >>> long time. The IETF came up with shim6, which allows multihoming >>> without BGP. Unfortunately, ARIN started to allow IPv6 PI just in >>> time so nobody bothered to adopt shim6. > >> That's a fairly simplistic version of why shim6 failed. A better reason >> (appart from the fact the building an upper layer overlay of the whole >> internet on an ip protocol that's largely unedeployed was hard) is that >> it leaves the destination unable to perform traffic engineering. > > I'm not saying that shim6 would have otherwise ruled the world by now, it was > always an uphill battle because it requires support on both sides of a > communication session/association. > > But ARIN's action meant it never had a chance. I really don't get why they > felt the need to start allowing IPv6 PI after a decade, just when the > multi6/shim6 effort started to get going but before the work was complete > enough to judge whether it would be good enough. > >> That fundementaly is the business we're in when advertising prefixes to more >> than one provider, ingress path selection. > > That's the business network operators are in. That's not the business end > users who don't want to depend on a single ISP are in. Remember, shim6 was > always meant as a solution that addresses the needs of a potential 1 billion > "basement multihomers" with maybe ADSL + cable. The current 25k or so > multihomers are irrelevant from the perspective of routing scalability. It's > the other 999,975,000 that will kill the routing tables if multihoming > becomes mainstream.
When discussing 'why shim6 failed' I think its only fair to include a link to a (well reasoned, imho) network operator's perspective on what it did and did not provide in the way of capabilities that network operators desired. http://www.nanog.org/meetings/nanog35/abstracts.php?pt=NDQ3Jm5hbm9nMzU=&nm=nanog35 -Darrel