Subject: [Softwires] draft-xli-behave-divi-pd

From: Nejc Škoberne <[email-masked]>
Date: Wed, 31 Aug 2011 00:23:15 +0100

Dear authors,

I have some comments and questions regarding draft-xli-behave-divi-pd:

1. If I understand correctly, each CPE is delegated a prefix of length
56 to 64 bits. The CPE can then do SLAAC for the network behind it, using
any of the subprefixes of the delegated prefix. Is this correct?

2. What IPv6 address is/should be configured on the CPE in the access
network? Can this be any IPv6 address?

3. To me it seems that there is redundant information in the address
format - CPE index is encoded in the prefix (as "k" bits of the CPE index)
and in the suffix (as k). If I understand correctly, similar is true for
IPv4 address - the "s" bits in the CPE index uniquely identify one of
the shared IPv4 addresses. What exactly is the motivation for this? I mean,
IPv4 address and the port range are not encoded in the prefix anyway,
so direct CPE-CPE paths are not possible? I miss packet flow diagrams.

4. I can't understand how exactly is "IPv4-converted address block"
supposed to be used. I really miss packet flow diagrams here. Also, you
seem to mix IPv4-converted and IPv6-converted.

5. There is an example in Appendix A, which I cannot completely understand. 
I cannot see how "v" (is this "s" in the CPE index?) is represented in
the IPv4-translatable address?

Since you claim you have been running an implementation in production
successfully, I assume you have all these things sorted out. But I think
that the draft needs some more work to be understandable to others.

Thanks,
Nejc