shim6 @ NANOG

Roland Dobbins rdobbins at
Sun Mar 5 04:48:58 UTC 2006

On Mar 4, 2006, at 7:06 PM, Joe Abley wrote:

> No support in big networks is required, beyond the presence of  
> shim6 in server stacks.

Why do you say this?  Enterprises who multihome need their client  
machines (tens and hundreds of thousands of them) to be able to take  
advantage of multihoming, as well.  It's a requirement, not a luxury.

[Note that I do not address the blurring of client and server roles  
which is happening even now, and which will almost certainly become  
more prevalent over the anticipated lifetime of the success protocol  
to IPv4.]

This fundamental misconception of the requirements of large  
enterprise customers should be an indicator to proponents of shim6,  
among others, that they do not have a good grasp of the day-to-day  
operational and business realities faced by large enterprises.  This  
lack of understanding has led to such fundamental misconceptions as a  
belief that large enterprises can accept frequent renumbering within  
their organizations based upon changing business relationships with  
their SPs (they cannot, see RFC 4192 for some of the reasons why  
not), as well as underestimating the importance of multihoming for  
client computers as well as servers.

shim6 is simply not viable for large enterprises, who are the  
customers who require multihoming.  I would argue that it's not  
really viable for smaller organizations either, due to the complexity  
it adds to the troubleshooting matrix for support staff.  I hope that  
the operational community will turn to more fruitful lines of enquiry  
regarding IPv6 multihoming.

Roland Dobbins <rdobbins at> // 408.527.6376 voice

      Everything has been said.  But nobody listens.

                    -- Roger Shattuck

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