Re: [Softwires] Fw: New Version Notificationfordraft-cui-softwire-b4-translated-ds-lite-04.txt

["Peng Wu" <[e-mail]>]

Hi Reinaldo,

inlines :)
--------------
Peng Wu

>> The first and the major one is that, if we just take ds-lite and have static
>> port set allocation in the concentrator, the concentrator still has to keep
>> the per-session NAT table and perform the translation, while in lightweight
>> 4over6, NAT happens on CPE and the concentrator just perform
>> encapsulation/decapsulation, with a per-subscriber mapping table.
>
>Per-session NAT is not needed if:
>
>- the B4 performs NAT or
>- Each host has a unique IP and a known port space.
>
>Our implementation performs NAT without any per session state.
Could you go a little further into this? 
I'm actually confused how you do NAT without (source IP, 
source port, dst IP, dst port) mapping table

>
>> 
>> The second one is that in lightweight 4over6, with one-time DHCP/PCP,
>> the subscriber learns its public IPv4 address. This brings convenience and
>> eases the ALG problem to a certain extent.
>
>I think ALG is an application issue and can only be fully solved when all
>applications make use of PCP.
Well, my point is, if the whole problem is just a local 44NAT(as is in leightweight 4over6), 
then we already have uPnP, and end host don't need PCP to negotiate with the AFTR 
which is  probably a remote, big network device.
>
>> In ds-lite with static concentrator
>> port allocation, the subscriber still doesn't know its public IPv4
>> address/port 
>> without per-session PCP process.
>
>Yes, that is a good point. We devised an extension to PCP to return the
>public IP and port range. Therefore a single message would be needed.
Similar idea. But I still need your elaboration on the principle of this
 none-session-state NAT thing to get the whole picture.
>