Comments on draft-ietf-udlr-lltunnel-01.txt

[Dave Thaler <dthaler@dthaler.microsoft.com>]

I saw the IETF last call announcement, read through the draft, and have
the following comments:

1) This draft claims to be a link-layer tunnelling mechanism,
   and from the title and abstract, I would expect it to
   work for any layer-3 protocol (IPv4, IPv6, IPX, whatever),
   like GRE does.  Is it the intent that this should ONLY work 
   for IP packets?  If so, the abstract should clarify this if the 
   title doesn't.  If not, then wording in several sections needs 
   to be cleaned up (6.2.1 is a good example, but there are plenty).

2) I *think* I figured out the interface model, but I'm not sure.
   In particular, it's unclear as to whether the tunnels
   from receivers to feeds, and the tunnels from feeds to 
   send-only feeds, appear as interfaces themselves or not.  From 
   the current spec, my guess is they do not (and so they're
   different from real GRE tunnels), but either way, this could
   be made more clear.

   (Also, just for my edification, has there been any work on a 
   UDLR MIB?  What would one see looking at the Interfaces MIB?
   Should one even see any entries in the IP Tunnel MIB?)

3) Must "Feed UDL IP addr" always be the same as the source IP
   address in the HELLO message?  If so, why do you even have
   this field in the first place?  If not, when could it be different?

4) Section 6.3, item 1, says that a receiver must create "a tunnel"
   (implying exactly one) when a new feed comes up.  6.3.1 then
   says the feed may include multiple FBIP's, in "preferred order".
   6.3.4 item 1 then says that "the corresponding FBIP1" is used
   implying that FBIP2 .. FBIPn are not used.  If exactly one
   tunnel is created, and it always uses FBIP1, then what are
   the other addresses for?

5) If a feed is dual-stack IPv4/IPv6, does it send out two HELLO
   messages, one for IPv4 and one for IPv6?  If so, how does this
   affect the Interval parameter?  Is it the interval between
   HELLOs for the same address family, or is it the interval
   between HELLOs for any address family?

6) Section 6.3 uses "FBIP" before it's defined (later in 6.3.1)
  
7) Lots of typos: "administator", "occure", "occures",
    "encapsultion", "encapsulaton", "Encapsultation", "encapsultate"

8) Figure 3, lines on right edge don't line up

-Dave Thaler