shim6 @ NANOG

Iljitsch van Beijnum iljitsch at
Sun Mar 5 14:03:43 UTC 2006

On 4-mrt-2006, at 22:31, Matthew Petach wrote:

> And given that any network big enough to get their own PI /32 has  
> *zero*
> incentive to install/support shim6 means that all those smaller  
> networks
> that are pushed to install shim6 are going to see *zero* benefit  
> when they
> try to reach the major sites on the internet.

A case can be made that some big sites sitting high and dry wouldn't  
care enough about their customers to do shim6 with them if they're  
multihomed using shim6, but that's not the same thing as there being  
zero benefit. Especially in a competitive market place: what if  
Hotmail runs shim6 so that multihomed Hotmail users can keep sending  
mail even when one ISP fails, while Gmail doesn't?

You assume that all the big sites will get PI /32s and that this will  
allow them to multihome the way they want. I'm sure _some_ big sites  
will get a /32 or /48 or other PI block, but it remains to be seen  
whether all do. And having a single block isn't enough if you connect  
to the net in various locations but don't want to backhaul traffic  
between those locations yourself.

>> Yes, this is an issue. If we have to wait for a major release or even
>> a service pack, that will take some time. But OS vendors have
>> software update mechanisms in place so they could send out shim6 code
>> in between.

> And no major company supports/allows automated software update
> mechanisms

Dit I use the word "automated"?

> But again, it cuts both ways: if only two people run shim6 code,
> those two people gain shim6 benefits immediately.

> Cool.  So let individuals make a choice to install it if they  
> want.  But
> that's a choice they make, and should not be part of a mandated IP
> allocation policy

Nobody is forced to implement shim6 if they don't want. But not  
liking shim6 doesn't buy you PI in IPv6.

> shim6 is _more_ anti-competitive than extending the existing IP  
> allocation
> policies from v4 into v6, and is therefore not going to garner the  
> support of
> the companies that actually spend money to create this thing we  
> call the
> Internet.  And without money behind it, the effort is a non-starter.

2 million prefixes in a router that supports 1 million is also a non- 

Insisting that shim6 isn't going to work is a waste of time, because  
it doesn't do anything to make shim6 better so it could work or  
create alternatives, it just adds FUD.

> I have more faith in our ability to deal with route table growth  
> than I do
> in our ability to come up with a viable instantiation of shim6.

Engineering based on faith is insane. Even with today's science we  
have balconies falling off of appartment buildings and roofs  
collapsing when it rains or snows a bit harder than usual, so a  
little caution here and there isn't too much to ask for.

More information about the NANOG mailing list