draft-bonica-tunproto-04.txt

["Adrian Farrel" <afarrel@movaz.com>]

Hi Ron,

Some thoughts on re-reading this draft...

I think the draft is long enough to need a contents table.

Although the access control function is mandatory, why is the Access Control
Object mandatory on a traceProbe? If the requester has nothing to say and the
reporter is happy with that, why force the object to be present?

It wasn't clear to me until reading the section on head-end object timestamps
that the traceResponse is routed back through the head of the tunnel. Doesn't
this assume that you have a bidirectional tunnel? Apart from the round-trip time
function, why wouldn't you send the traceResponse back to the source by a more
direct route?

Isn't there a problem with the TTL method of finding the next hop? The path of
the tunnel may change from one probe to the next giving the appearance of loops
(gaps are less important). You either need to describe apparent loops and how to
prune them, or you need to use another hop identification mechanism.

Why is the Access Control Object present on the traceResponse?

Format diagrams - all the bit counts need to right-shift by one.

Is the ordering of objects in messages mandatory, suggested, optional?

Was there a protocol version 0?

Lengths. Message lengths appear to be inclusive, object lengths exclusive.
Consistency would be nice. When you describe the individual objects the length
values you give are actually inclusive. Note also that object lengths refer to a
count of 32-bit words that follow, but are often (never?) the last byte in a
32-bit word.

Errors. For unknown, malformed and missing objects it is nice to be able to
indicate the object type that is in error. Note also, that if the error is
missing object, it may not be possible to correctly format a TraceResponse
Message.

Addresses here are only IPv4. Would it be worth including IPv6 variants?

Need an error code for IP Header and Tunnel Object both present?

5.2.7 missing description of hop count

Need error needed for hop count flag set and responder address present?

Several places say "can be 0 padded for word alignment". I think this should
read "MUST".

5.2.11 Support for unnumbered interfaces?

5.2.12 Flags field. Which bit is bit 0? Compare Propagation Object where you say
"right-most bit".

Tunnel type.  GRE?

I think the security section needs some oomph!

Cheers,
Adrian