RE: NOTE: WG Last Call: draft-ietf-v6ops-mech-v2-01.txt

["Pascal Thubert (pthubert)" <pthubert@cisco.com>]

> -----Original Message-----
> From: owner-v6ops@ops.ietf.org [mailto:owner-v6ops@ops.ietf.org] On
Behalf Of Dave Thaler
> Sent: lundi 24 novembre 2003 19:30
> To: Erik.Nordmark@Sun.COM
> Cc: v6ops@ops.ietf.org
> Subject: RE: NOTE: WG Last Call: draft-ietf-v6ops-mech-v2-01.txt
> 
> This is the issue I mentioned again in Minneapolis...
> 
> From draft-ietf-v6ops-mech-v2-01.txt:
> >
> > 3.2.1.  Static Tunnel MTU
> >
> >    A node using a static tunnel MTU MUST limit the size of the IPv6
> >    packets it tunnels to 1280 bytes i.e., treat the tunnel interface
> as
> >    having a fixed interface MTU of 1280 bytes.  An implementation
MAY
> >    have a configuration knob which can be used to set a larger value
> of
> >    the tunnel MTU than 1280 bytes, but if so the default MUST be
1280
> >    bytes.  A larger fixed MTU should not be configured unless it has
> >    been administratively ensured that the decapsulator can
reassemble
> >    packets of that size.  Care should be taken when manually
> configuring
> >    large tunnel MTUs to only do so when the MTU of the IPv4 path to
> the
> >    tunnel endpoint is large to avoid causing excessive
fragmentation.
> 
> Here's a scenario which may become common:
> 
> A mobile node has
> 1) an Ethernet interface connected to a v4-only network
> 2) some type of IPv6 over IPv4 tunnel that follows this spec,
>     where the IPv4 address used for encapsulation is the address
>     on interface 1.
> 3) an IPv6 over IPv6 tunnel to its home agent to support mobile IPv6,
>     where the IPv6 address used for encapsulation (i.e. its
> care-of-address)
>     is the IPv6 address on interface 2.  With route optimization
> optional,
>     one common case is where the majority of communication would be
over
> 
>     this interface (reverse tunneled).
> 

Hi Dave:

On the side of this discussion, note that it would be beneficial to
MIPv6 to consider IPv4 traversal in order to save the intermediate
tunnel. It's very unclear where this discussion should take place. I
proposed to Nemo a year ago, and the WG said it was a MIPv6 problem. I
asked P2P to some MIPv6 members, who answered to me it was more likely
to be a v6Ops problem.

What do you think?

Pascal