[trill] draft-ietf-trill-o-pw comments

[Erik Nordmark <[e-mail]>]

I've reviewed the document before writing up the PROTO.
A few requests for clarifications.

The two packet formats include a specific bit pattern:
       |      PPP Header 0x005d        |  2 octets

       |      PPP Header 0x405d        |  2 octets

For the un-initiated it would make sense to add a reference in the text 
below the figures. Something like "The PPP Header (0x005d and 0x405d 
respectively) is the header for data frames and IS-IS packets as 
specified in RFC XXX". (Or something in that vein.)

In security considerations we have
    For security considerations introduced by carrying PPP TRILL links
    over pseudowires, see [RFC3985].
I assume RFC 3985 doesn't talk about TRILL - but about PPP in general. 
Thus it would be more clear if we drop "TRILL" from that sentence.

The 3rd paragraph starts with
    Not all implementations need to include specific security mechanisms
    at the pseudowire layer ...
Is this a relaxation of the general PW security requirements? Or merely 
re-stating the stance for security for PW? It would make sense to spell 
that out in the document.

    Erik