Re: [babel] info-model: message log

["STARK, BARBARA H" <[e-mail]>]

> >> (Note that picking a dump format doesn't mean we can parse it --
> >> there's the small matter of the encapsulation used, which could be
> >> 802.2, radiotap, raw IPv6, or something else.  Do we need to specify
> >> that?)
> 
> > Encapsulation is the job of the management protocol. The info model
> > will allow the file to be exposed...
> 
> That's not what I meant.  Pcap and pcapng contain a sequence of frames --
> these frames can be using a number of different encapsulations.
> 
> Here are the cases I'm familiar with:
> 
>   - pcap can contain a sequence of Ethernet frames;
>   - pcap can contain a sequence of 802.2 SNAP frames;
>   - pcap can contain a sequence of radiotap frames which themselves
>     contain whatever is carried by the 802.11 link (typically 802.2 SNAP).
> 
> Is it legal for an implementation to expose, say, PPP frames in the pcap file?
> Do we need to formalise the allowed encapsulations contained within the
> pcap file, or are we going to assume implementers do something
> reasonable?
> 
> (I'd argue in favour of being liberal here -- being restrictive might cause issues
> if at some point Babel is carried over exotic link layers, and after all one of
> Babel's strengths is that it's link-layer-agnostic.
> But I think it deserves discussion.)

Ah. I understand now (I hope). I see no need to be restrictive. The data link type is specified in the file header (using values from http://www.tcpdump.org/linktypes.html).  I think it's the responsibility of whatever is reading the file to be able to comprehend the link types of the Babel deployment. If you deploy Babel in an exotic environment, you need to have the tools that understand your exotic environment. I'm often accused of being liberal.