Date: Tue, 17 Oct 2006 10:03:05 -0700 From: "Krejsa, Dan" <dan.krejsa@windriver.com> To: "JINMEI Tatuya / ????" <jinmei@isl.rdc.toshiba.co.jp> Cc: freebsd-net@freebsd.org Subject: RE: PPP IPv6 prefix length and stateless autoconfiguration? Message-ID: <F7D1E22E318B7148B9EF6345A57821D901DA8BE8@ALA-MAIL03.corp.ad.wrs.com>
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Hi Jinmei, Thanks for your reply! I'm actually working on an OS which uses a FreeBSD and Kame-derived stack, very similar in its IPv6 code to the current FreeBSD. The PPP code is of a different derivation, however. It specifies a 128-bit subnet mask and sets a destination address for PPP/IPv6 interfaces, and we consequently saw an issue with IPv6 autoconfiguration. As a workaround, I did exactly what you suggest, changed the code to configure the interface with a 64-bit prefix without a destination address (actually, the code tried but failed to set the destination address, but I didn't notice it at first). This appears to make the autoconfiguration work fine, and I encountered no other connectivity issues in brief testing; but a coworker of mine noticed that ifconfig no longer showed the destination address, and I investigated and found the 128-bit enforcement in in6_update_ifa(). This makes me somewhat nervous; but if configuring a PPP/IPv6 interface without an IPv6 destination address is the intended method of use, I'd be more comfortable with this. Is that the standard way of doing things? Thanks, - Dan -----Original Message----- From: JINMEI Tatuya / ???? [mailto:jinmei@isl.rdc.toshiba.co.jp]=20 Sent: Monday, October 16, 2006 7:40 PM To: Krejsa, Dan Cc: freebsd-net@freebsd.org Subject: Re: PPP IPv6 prefix length and stateless autoconfiguration? >>>>> On Mon, 16 Oct 2006 15:19:55 -0700,=20 >>>>> "Krejsa, Dan" <dan.krejsa@windriver.com> said: > Some code in the in6_update_ifa() function in netinet6/in6.c > enforces that if an IPv6 destination address is specified for > an interface address, the interface must be point-to-point or > loopback (fine), and the corresponding prefix length must be > exactly 128 bits. > The latter seems (at least naively) to conflict with=20 > the definition in > http://www.ietf.org/internet-drafts/draft-ietf-ipv6-over-ppp-v2-02.txt > that the interface identifier length for PPP interfaces is 64 bits, and > correspondingly prefixes accepted from a router advertisement > must also be 64 bits long; see section 5.5.3 in > http://www.ietf.org/internet-drafts/draft-ietf-ipv6-rfc2462bis-08.txt So shouldn't you simply specify the prefix length of 64 without specifying the *destination* address of the p2p link? JINMEI, Tatuya Communication Platform Lab. Corporate R&D Center, Toshiba Corp. jinmei@isl.rdc.toshiba.co.jp
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