Re: IP MPE payload

[Lloyd Wood <l.wood@eim.surrey.ac.uk>]

On Tue, 30 Oct 2001, Patrick Cipiere wrote:

> > In your previous mail, you were suggesting redefining the bit from
> > indicating
> > (LLC_SNAP encap)/(raw IP datagram) to indicating
> > (raw IPv4 datagram)/(raw IPv6 datagram).
> 
> By no way I want to redefine any bit. I just want to use it the
> way the standard is designed.
> 
> LLC_SNAP_flag == 0 means payload raw IPv4
> LLC_SNAP_flag == 1 means whatever is in the AAL5 (see  RFC1483)
>                    if AAL5 Ethertype == 0x86DD then IPv6

Ah, that's slightly clearer and I understand your previous mails
better...

...but then you wouldn't need the flag, since IPv4 has an Ethertype
anyway. And if you used the flag this way you'd favour IPv6 rather
than 4 - since IPv6 has bigger headers and MTU requirements, and
benefits from the added space resulting from removing the encap.

...but there is no mention of AAL5 in EN 301 192. Why would you want
the additional overhead of AAL5 encapsulation/checksumming etc - and
when you say 'the standard', which standard are you referring to?

...but DVB != ATM... going through AAL5 doesn't get you anywhere near
a decent IP over DVB encapsulation, and afaik DSM-CC doesn't have to
use AAL5 as the broadcast type. 

And EN 301 192 (V1.2.1 199-06) talks about IP, not IPv4.

still puzzled,

L.

<L.Wood@surrey.ac.uk>PGP<http://www.ee.surrey.ac.uk/Personal/L.Wood/>