Re: [Softwires] Unified Softwire CPE: draft-bfmk-softwire-unified-cpe

[Ole Trøan <[e-mail]>]

Med, et al,

> Med: The rationale we adopted in this draft is as follows:
> 
> * there are three major flavors: full stateful, full stateless, and binding mode
> * all these modes can support assigning a full or a shared IPv4 address

now you got me thinking, are these really the right modes from a CPE perspective?

let me try to explain, with my CPE implementor hat on, what "modes" would make sense?

- NAT placement. do I need a NAT on the CPE or not?
  (no NAT && no IPv4 address == DS-lite)
- full IPv4 address assigned.
  I can assign the IPv4 address to the tunnel endpoint interface, and use that address for
  local applications, and as the outbound address of the NAT
  (mechanisms: MAP, Public 4over6)
- IPv4 prefix assigned:
  I need to disable the CPE NAT, and use the assigned IPv4 prefix as my LAN side DHCPv4 pool
  (mechanism: MAP)
- Shared IPv4 address.
  I must enable a local NAT, I cannot assign the IPv4 address on the "WAN" interface, but only use it
  for the outbound side of the NAT.

then there might be a sub-modes for "tunnel endpoint determination" i.e. how to determine an IPv6 tunnel end point address given an IPv4 destination address and port.
1) algorithmic (MAP)
2) configured (Public 4over6, LW46, DS-lite)

and a sub-mode for IPv4 address configuration:
1) As "native IPv4"
    (Public4over6, LW46)
2) Embedded Address
    (MAP)
3) None
   DS-lite

does this make sense?

cheers,
Ole