Re: OMB: IPv6 by June 2008

[Iljitsch van Beijnum <iljitsch () muada com>]

On 12-jul-2005, at 19:52, Phillip Vandry wrote:

> > In the mean time, we need SOME IPv6 so that the
> > early adopters can find those kinks, and that part is right on track.

> How are people making the case for IPv6 with popular applications like
> voice?

Dunno, but it can't be many.

> With G.711 and 20ms voice samples, with IPv4 you get:

> 20 bytes IP + 8 bytes UDP + 12 bytes RTP + 160 bytes payload
> 20% overhead.

Yes. It gets worse when you add compression.  :-)

> Now with IPv6. Say we use shim6 or something like that to implement
> multihoming too. The shim6 header isn't decided yet, but I suppose  
> it's
> got to contain at least a pair of addresses (32 bytes).

I'm still fighting the good fight on that one. Hopefully, there won't  
be a header, and if there is, it's only going to be there when there  
was a failure (ie the multihoming kicked in) and the size would  
almost certainly be 8 bytes. But that's all still up in the air.

> 40 bytes IP + 32 bytes shim6 8 bytes UDP + 12 bytes RTP +
> 160 bytes payload
> 36.5% overhead

Without a shim6 header it would be 60 out of 220, with a shim6 header  
most likely 68 out of 228, so 27% or 30%.

> Almost twice as much overhead is a much tougher pill to swallow. I  
> would
> try to stay with IPv4 as long as I could. Even without adding shim6
> into the picture you're taking a significant penalty.

This doesn't so much show an IPv6 problem but rather that voice over  
IP is extremely inefficient. Those TDM guys were on to something...  
Too bad the TDM networks are left to rot in the ground as we speak.  
Mark my words, we're going to regret letting this happen at some  
point in the future.