Subject: (ngtrans) Input Part 2: draft-ietf-ngtrans-6to4-03.txt

From: Sowmini Varadhan <[email-masked]>
Date: Thu, 2 Dec 1999 14:54:52 -0500 (EST)

Brian, Keith:

Here is (concluding) Part 2 from several members of the Compaq IPv6 engineering 
team (Jack McCann, Sowmini Varadhan, Vlad Yasevich, Ken Powell, Jim Bound). 

- Some explanation around the figures in Section 5.4, to describe
  the various components of the figures, and what traffic will/won't
  work? 

- "5.6 Transition considerations
   :
   3. Identify a 6to4 relay router willing to relay the site's
   traffic to the native IPv6 world. ... Configure
   a default IPv6 route to that relay router,..."

  Why is it necessary to configure a default route, when, on Page 9,
  (paragraph on the top of the page) has already mandated that

  " ... The relay router MUST
   advertise whatever native IPv6 prefixes are appropriate on its 6to4
   pseudo-interface."

- Add something like the following line to Section 5.8 ("Usage within 
  Intranets")

  "If the V4ADDR is not globally unique (i.e., it is only unique within
  the private network), the corresponding 2002::/48 prefix MUST NOT be
  advertised outside the Intranet."

- It's not clear to us how/when a multicast packet gets sent on a 6to4
  network in the form described below. 

  "..However, nothing prevents IPv6 multicast packets being sent to or
   sourced from a 6to4 router encapsulated in IPv4 unicast packets
   exactly as defined in Section 4."
				- [ Section 6, Page 15, first paragraph]

  Our understanding from the [sending_rule] is that the only way
  to construct the IPv4 header is by extracting the V4ADDR from the
  IPv6 destination/next_hop, but the above statement seems to 
  indicate that packets of the form

      [v4src > v4dst] [v6src > ff02::dada] [ data]

  can be sent, where v4src and v4dst are unicast IPv4 addresses, and
  ff02::dada is a V6 multicast. How is v4dst constructed? When does this
  happen?

- on a related note, the following line:
  "                                    ... However, multicast
   traffic may follow an incongruent path, and when relay routers are in
   use, paths will be congruent only if relay routers are positioned and
   configured appropriately. " 
				- [ Section 5.9, Page 14, last paragraph]

   could use some clarification. Does "multicast traffic" refer to
   6to4 (i.e., encapsulated) traffic? To IPv6 traffic?

- Maybe a Reference should be included for PIM in the bibliography?

Thanks
Sowmini

---

From: Brian E Carpenter <[email-masked]>
Date: Thu, 02 Dec 1999 16:15:52 -0600

Thanks, we'll look at these for the next update. I still have your Part 1
filed for action.

  Brian