Subject: Tunnels and diffserv question

From: Rémi Denis-Courmont <[email-masked]>
Date: Sat, 26 Aug 2006 01:05:25 +0300

Hello,

I was looking at RFC 2983 (Diffserv and tunnels)... and now, I'm left 
wondering: how (if at all) does/should this apply to IPv6 transitions 
mechanisms (6to4, Teredo, ...) ?

Anyone has a hint there?

Regards,

-- 
Rémi Denis-Courmont
http://www.remlab.net/

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From: Jeroen Massar <[email-masked]>
Date: Sat, 26 Aug 2006 02:14:35 +0200

> mechanisms (6to4, Teredo, ...) ?

The abstract mentions "IP tunnels of various forms", section 6 
explicitly mentions "IPv6 over  IPv4 tunnels (RFC1933)". This in special 
and the rest of the text makes it seems to be fully applicable to all 
the other transition mechanisms. Simply copying over the inner ToS/DS 
field to the outer one should be sufficient. I haven't seen any 
implementation actually doing this though, but it could be that some 
implementations already do it in that manner.

Greets,
  Jeroen

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From: Rémi Denis-Courmont <[email-masked]>
Date: Sat, 26 Aug 2006 13:09:59 +0300

Le samedi 26 août 2006 03:14, vous avez écrit :
> explicitly mentions "IPv6 over  IPv4 tunnels (RFC1933)". This in
> special and the rest of the text makes it seems to be fully
> applicable to all the other transition mechanisms. Simply copying
> over the inner ToS/DS field to the outer one should be sufficient.

Right, thanks. That's the first conceptual model from §3.1. I was merely 
wondering if it was recommended that 6to4, Teredo (and ISATAP?) use the 
first or the second model... it does not make much sense, I think, to 
have different model implemented by different nodes since they are all 
part of the same multi-point pseudo-tunnel.

> I haven't seen any implementation actually doing this though, but it
> could be that some implementations already do it in that manner.

Anyway, I'm afraid this is hardly implementable in practice, since there 
is no IPv4-equivalent of the sendmsg() IPV6_TCLASS option, but that's 
slightly off-topic.

-- 
Rémi Denis-Courmont
http://www.remlab.net/

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From: Brian E Carpenter <[email-masked]>
Date: Sun, 27 Aug 2006 08:45:42 +0200

> is no IPv4-equivalent of the sendmsg() IPV6_TCLASS option, but that's 

That shouldn't matter, assuming the tunnel end-point is below the socket
API or somewhere inside the network. It should map the DSCP regardless of
who set it. Today, DSCPs are usually set by policy or by a classifier,
not by an API.

     Brian

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From: Brian E Carpenter <[email-masked]>
Date: Sun, 27 Aug 2006 08:40:51 +0200

Rémi,

It was certainly intended to apply to all kinds of tunnels, although
the hardest issues are for IPsec tunnels.

Since diffserv works identically for IPv4 and IPv6, there should be
no particular difficulties, just code...

    Brian

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From: Fred Baker <[email-masked]>
Date: Sun, 27 Aug 2006 07:31:11 -0700

On Aug 25, 2006, at 5:14 PM, Jeroen Massar wrote:

> Simply copying over the inner ToS/DS field to the outer one should  
> be sufficient. I haven't seen any implementation actually doing  
> this though, but it could be that some implementations already do  
> it in that manner.

the more important question is copying it back to the inner header on  
removal from the tunnel. This is optional in that specification, and  
I know of field deployments that do it either way.

Yes, common implementations do this.

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From: David Malone <[email-masked]>
Date: Sun, 27 Aug 2006 21:01:35 +0100

On Sat, Aug 26, 2006 at 02:14:35AM +0200, Jeroen Massar wrote:
> I haven't seen any 

The KAME gif tunnel interface should be able to do this - it's an
option when configuring the interface with ifconfig.

	David.