[Softwires] Comments on 4rd-u-04

[Washam Fan <[e-mail]>]

Hi,

Eventually I get a chance to review this version and have some major
comments and questions as below.

1. Relationship with MAP, MAP-T, MAP-E.
I thought, MAP was expected to be a generic algorithm for stateless
mapping IPv4 addresses to IPv6 addresses and vice versa. I thought,
MAP would apply to MAP-T, MAP-E as well as 4rd-u. But draft 4rd-u-04
doesn't mention MAP draft. And I see the mapping rules stuff in the
draft overlapped with MAP. Confused.

I thought, 4rd-u is competing with MAP-T and MAP-E to some extend.
Would you mind expaund on what benefits 4rd-u can gain exclusively?
Ideally, there would be a seperate section or even a seperate draft
for such comparison.

2. NAT64+ stuff.
My understanding, NAT64+ would translate 4rd tunnel packet as well as
native IPv6 packet to IPv4 packet and vice verse. Right? I don't know
what the CE delegated prefix in NAT64+ looks like. Can the native IPv6
and 4rd shared the same delegated prefix? if Yes, how to distinguish
them? the figure 6 seems to me it was talking about destination IPv6
address derivation.

IIRC, NAT64 supports hair pinning, doesn't it? Would NAT64+ support
harpinning between 4rd tunnel packet and native IPv6 packet?

Personally, I'd like NAT64+ removed from the draft. It might deserve a
seperate draft. This way, it would make the draft more understanding
for readers who are new to 4rd-u.

3. Fragments.
The algorithm proposed in R-9, would have applied to generic NAT
generally. Why it is specific to 4rd BR? Anyway BR would keep fragment
state somehow and anycase BR facing IPv4 Internet would be impossible.

Thanks,
washam