Dear Nejc,
On 2011/08/17, at 22:58, Nejc Škoberne wrote: > Dear Gang, > >>> as far as I can understand your draft, you make NAPT44 in the CE obligatory. >> >> [Gang] Yes. This is to avoid the problem where there are applications >> that attempt >> to bind to specific ports that are not part of the allowed port range. > > Well, if the application/operating system supports the > standard/protocol/technology, then it should only bind to the port, which > CPE would normally use to translate source ports of the packets. If there > is no such operating system/application, NAPT44 must be used, of course. > >>> However, this is not the case for 4rd, dIVI, SA46T-AS and Lightweight >>> 4over6 A+P drafts. >> >> [Gang] I guess this is always the case for port constrained mechanisms. > > Of course. But you could support various scenarios in the scope of your draft, > not only the common "CPE" one. > We assume that all applications/OSes doesn't aware port restricted environment. However, there is a case where an application would be allocated a port which is inside of port set occasionally. >>> So I suggest that you make it optional in 4via6 translation as >>> well, since it might >>> be desired for some environments to connect hosts supporting 4via6 >>> translation >>> technology, directly to the IPv6 network. In this case, you don't need >>> the translator. >> >> [Gang] Could you help to elaborate the environment ? > > Sure. I can imagine a Linux implementation of "4via6 translation > support". If enabled, the TCP/IP stack would only bind to specific ports > (from the range). If you check the section III./C of the following paper: > > http://zhuyc.info/globecom08mivi.pdf > > the authors propose a modification "to the system call related to bind() > in the socket library of the operating system". > The modification of 'to the system call related to bind()' is out of scope in our draft. > Then I could just connect my home gateway-server directly to the ISPs > network, providing support for "4via6 translation" and that's it. > > Also, I see is as a use case in non-ISP environments, where you could > have IPv6-only, but 4via6 enabled server networks, with servers supporting > "4via6 translation". Like SA46T-AS, for example. > > The main advantage of all this is of course that the IPv4 address is then > natively configured on the (virtual) interface. > > -- > > Other than that, I still am very curious what are the differences between > your draft and draft-xli-behave-divi-03. I would be very happy if you could > elaborate on that. IMHO, address mapping rule and port distribution algorithm are the difference. Let me think that if 4rd is configured with 'DomainIPv6Prefix == 2001:db8::/32', 'CEIPv6PrefixLength == /72' and 'Domain4rdPrefix == 0/0' for example. 40bits EA-bits are divided to 32bits IPv4 address part and 8bits port-set ID part. The length of the port-set ID expresses that address sharing ratio. The bits pattern of the port-set ID expresses port-set index of modulo operation, described in the divi. cheers, --satoru _______________________________________________ Softwires mailing list Softwires@ietf.org https://www.ietf.org/mailman/listinfo/softwires
