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

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

On Apr 12, 2011, at 2:11 AM, Dmitry Anipko wrote:

> Hi,
> 
> Since re-chartering to include 4rd has not been approved yet (as far as I know), I'm not sure if softwires is the right forum for this question, please let me know if intarea is a better one for the time being.
> 
> Draft-despres-intarea-4rd-01 allows for configuration of end hosts (since it defines CE as "a host, a router or both") with shared addresses with restricted port sets. My understanding is that usage by applications of such addresses, assigned to interfaces, may have issues - for example, those are discussed in http://tools.ietf.org/html/draft-dec-stateless-4v6-00 . 
> 
> Should the draft include a recommendation to either avoid assigning such addresses to interfaces, and use it only in the NAT function, even when CE is a host, or, as draft-dec-stateless-4v6-00 suggests in section 3.1.2, modify the 4rd DHCP option to provide for CE ability to specify whether it is capable to function with a shared address? (since 4rd can also distribute not shared addresses / address ranges)
> 
> Thank you,
> Dmitry
> 
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