[mdlug] OT: the great IPv6 debate

[Dan Pritts]

On Thu, Apr 22, 2010 at 03:28:35PM -0400, Adam Tauno Williams wrote:
> Nah, working multicast and mobile IP support are a big deal.

IPv4 SSM works more or less as well as IPv6 multicast does.

Mobile IP support, yeah, that's cool.

> And I hardly call the radical reduction of CPU resources to perform
> routing to be 'gravy' for backbone routers.  Think about it: IPv4
> requires a CRC check at each hop,  do that on every packet in a ^&*^&*@
> YouTube video stream for every &^&*# YouTube user at every hop and that
> adds up to a lot of processing, ASIC or no ASIC.  Just dispensing with
> that is a big deal.

somehow, all the packets get moved.  It's a lot less effort to do this in
the network than it is to change absolutely everything 


> > Probably the biggest problem is that application software often
> > does not handle things gracefully when a supposedly dual-connected
> > site is v4-reachable but not v6-reachable.
> > Try an experiment; put a bad AAAA record in your DNS for a test web
> > server, try to connect using a browser on a v6-configured host.
> > (put in a good A record, too).
> 
> Eh.  Seriously, that is your complaint?  Fix your DNS.  I don't expect a
> client application to compensate for incorrect information.

My complaint isn't what happens when DNS is broken.  My problem is 
what happens when:

  My system has a v6 and v4 address
  The server has a AAAA record and an A record.  
  I have v4 reachability but not v6 reachability to the server

This happens pretty frequently in my experience.  

Obviously this is a transitional problem - but it's a big one.

danno
--
dan pritts
danno at umich.edu
734-929-9770