Re: [Softwires] sharing restricted addresses by hosts in 4rd (draft-despres-intarea-4rd-01)

[Tetsuya Murakami <[e-mail]>]

Alain,

On 2011/04/19, at 9:06, Alain Durand wrote:

> 
> On Apr 12, 2011, at 4:03 PM, Mark Townsley wrote:
> 
>> 
>> Hello Dmitry,
>> 
>> My view is that 4rd is most easily understood if and only if it connects to a CE function that is performing NAPT. The CE function may be in what is traditionally considered a host, or in what is clearly a router.
>> 
>> More specifically, a device that is forwarding packets from one interface (virtual or otherwise) to another through a NAPT that has one interface with IPv6 configured (via DHCPv6 or otherwise) as performing 4rd (which enables dual-stack via a port-restricted IPv4 address for the NAPT using IPv6 as the transport) then you a have a 4rd CE. That could be a "host" in that it is a Windows PC with internet connection sharing for IPv4 turned on and hence forwards packets between interfaces with a NAPT due to the IPv4-enabled interface created when 4rd is configured. 
>> 
>> I would avoid anything that requires the host forwarding table to be altered to accommodate 4rd. Instead, the NAPT function that is already present in a small router or host configured to look like a router is modified to use a set of ports that it is allowed to use when 4rd is enabled. 
> 
> 
> Mark:
> 
> How would an app running on a 4rd CPE communicate in IPv4 to another app running on another 4rd CPE?

IPv4 address generated from assigned IPv6 address can be used in only 4rd CPE function. For example, this IPv4 address is used by only NAT44. So, the application running on 4rd CPE box does not use this IPv4 address generated from IPv6 address.

If the application supports IPv6, the application can use the assigned IPv6 address because each 4rd CPE has a unique IPv6 address. Also, if a private IPv4 address is assigned to IPv4 interface on 4rd CPE box, the application can use this private IPv4 address.

Thanks,
Tetsuya Murakami