Re: Shim6, was: Re: filtering /48 is going to be necessary

[Darrel Lewis <darlewis () cisco com>]

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