[sr-dev] git:master: Do not perform a lookup for IPv4 addresses, if only listening on IPv6 sockets.

[Klaus Darilion]

On 18.09.2012 09:40, Olle E. Johansson wrote:
>
> 17 sep 2012 kl. 21:11 skrev Klaus Darilion <klaus.mailinglists at pernau.at>:
>
>>
>>
>> On 17.09.2012 20:26, Olle E. Johansson wrote:
>>>
>>> 17 sep 2012 kl. 17:29 skrev admin at sip-router.org:
>>>
>>>> Module: sip-router
>>>> Branch: master
>>>> Commit: e1b3961b16b76b02ae7ad5f52b2e9db126f81ff9
>>>> URL:    http://git.sip-router.org/cgi-bin/gitweb.cgi/sip-router/?a=commit;h=e1b3961b16b76b02ae7ad5f52b2e9db126f81ff9
>>>>
>>>> Author: Carsten Bock <carsten at ng-voice.com>
>>>> Committer: Carsten Bock <carsten at ng-voice.com>
>>>> Date:   Tue Sep 11 19:39:32 2012 +0200
>>>>
>>>> Do not perform a lookup for IPv4 addresses, if only listening on IPv6 sockets.
>>>
>>> Hmm.
>>>
>>> What if I know that I have an outbound proxy that is dual stack?
>>>
>>> If the server listening to only IPv6 sockets needs to call me, it needs to know that the only target is IPv4 so either fail or forward to a dual stack proxy.
>>>
>>> Maybe this should be configurable. And of course, the opposite is true too. An ipv4-only server should be able to call IPv6-only by using another proxy.
>>
>> Do the DNS lookup for the external domain on the border element, which is dual-stack.
>
> Sorry, I wasn't very clear.
>
> If my proxy has an IPv6-outbound-proxy that I *ONLY* use for IPv6 gatewaying, I need to be able to make the routing decision locally. If my local IPv4-only server can't resolve IPv6 addresses, I have no way to figure out what's going on and make a decision that "this target is on IPv6 so I need to forward that to my IPv6-connected peer".

Indeed. That's a reason to not have an IPv6 *only* gateway ;-)

Anyway, shouldn't a proxy only have to deal with the next hop, not the 
next but one hop?

I think it would be really complicated to have the "next but one IP 
protocol" decision in the configuration file: you would have to DNS 
lookups (RFC3263) manually, and based on the result set the next hop 
address.

regards
Klaus