Wireshark · Ethereal-dev: Re: [Ethereal-dev] in need of an idea to support l2 tunneling over mpls

[Guy Harris <gharris@xxxxxxxxx>]

On Sun, Mar 17, 2002 at 10:13:11PM -0500, Aamer Akhter wrote:
> my idea was to allow the user to pick a specific label stack and layer2
> destination address (by picking the packet). and declare that it was of
> {EoMPLS, FRoMPLS, IP, ATMoMPLS, etc} type .

This sounds as if we might want to, for example, generalize the notion
of conversations and conversation dissectors, so that you can have more
types of conversations than just {TCP,UDP} conversations identified by
source and destination addresses and port numbers.

There are other places where such a generalization could come in handy,
e.g. for X.25 or ATM virtual circuits.

> The only framework that currently seems to allow
> that in ethereal is "Decode as" (which I admint, I haven't looked at the
> internals of yet).

"Decode As" doesn't really allow that.

You can specify that particular TCP or UDP port numbers, or particular
IP protocol numbers, or particular Ethernet protocol numbers, should be
decoded as a particular protocol; it does that by updating the dissector
tables for those fields.

It does not allow you to say "decode this *conversation* as this
protocol".  That would even be useful with TCP and UDP - you might not
want to say "port XXX should always be decoded as RTP", for example, you
might just want to say "*this UDP conversation* should be dissected as
RTP".

> Has something similar to what I'm suggesting already been attempted for
> another protocol?

No.