Ralph, I couldn't agree with you more. I don't like entangling prefix information with address assignment. It is so IPv4 thinking. I am off this discussion now since I don't believe in any IPv6 network that deploys DHCPv6 without a router or deployment where the router does not send RA's.
Further, I don't believe in sending prefix information that includes prefixes other than those associated with assigned addresses, just like I don't believe in any IPv6 network deployed without a router. A host can just receive prefix length and then host knows from its assigned address what is on-link for this host - I have assumed this host hasn't seen any RA because if the host does, then L-bit from RA has to be combined with prefix length for on-link determination. Any other prefix will be off-link and let the host send non-link-local traffic to default router. Hemant -----Original Message----- From: Ralph Droms (rdroms) Sent: Friday, August 17, 2007 12:48 PM To: IETF List IPv6 Mailing; [EMAIL PROTECTED] Subject: [dhcwg] Re: RE: Prefix information includes prefixes other than those associated with assigned addresses, or the case when the prefix associated with the address is not on link. Admittedly, the latter case is less than useful without a default router. But default router information might come from elsewhere. Why are we discussing taking a step *backward* in entangling prefix information with address assignment, when the separation of those two not-necessarily-related functions is one of the things IPv6 actually got right? Please step back from saving a couple of bits and think about the abstractions. - Ralph On Aug 17, 2007, at Aug 17, 2007,12:38 PM, Hemant Singh ((shemant)) wrote: > Ralph, > > What all information constitutes prefix information? If a node is > DHCPv6 > enabled in a RA-absent network, why isn't just the prefix length > enough > for the node to make an on-link determination with? In comparison, a > node that is DHCPv6 enabled in a RA-present network uses prefix length > and L bit together to make an on-link determination. > > Thanks. > > Hemant > > -----Original Message----- > From: Ralph Droms (rdroms) > Sent: Friday, August 17, 2007 12:27 PM > Subject: > > References: > <C6FE2907-79C0-4EB2-90AC- > [EMAIL PROTECTED]><7ECEF9368E169544B43882B > [EMAIL PROTECTED] > EXC-02.mgc.mentorg.com><8E296595B6471A4689555D > [EMAIL PROTECTED]><8C324AEB-292B-42E5- > A6B6-4 > [EMAIL PROTECTED]><[EMAIL PROTECTED]><F > DB > 98139-14EE-4D5F-B96D- > [EMAIL PROTECTED]><[EMAIL PROTECTED] > argle.gargle.HOWL><[EMAIL PROTECTED]><18115.3756.371573.10 > 32 > [EMAIL PROTECTED]><[EMAIL PROTECTED]><m1zm0reu44.wl > %jin > [EMAIL PROTECTED]><[EMAIL PROTECTED] > b- > rtp-20e.amer.cisco.com><[EMAIL PROTECTED] > >< > [EMAIL PROTECTED] > rtp-20e.amer.cisco.com><870 > 6B8AE-001D-4403- > [EMAIL PROTECTED]><B00EDD615E3C5344B0FFCBA910C > [EMAIL PROTECTED] > rtp-20e.amer.cisco.com><39C363776A4E8C4A94691D2BD9D1C9 > [EMAIL PROTECTED] > NW-7V2.nw.nos.boeing.com><B00EDD615E3C5344B0FFCBA910CF7E1 > [EMAIL PROTECTED]> <18117.50055 > [EMAIL PROTECTED]> > <[EMAIL PROTECTED]> > Mime-Version: 1.0 (Apple Message framework v752.2) > Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed > Message-Id: <[EMAIL PROTECTED]> > Cc: "James Carlson" <[EMAIL PROTECTED]>, [EMAIL PROTECTED], > "Templin, Fred L" <[EMAIL PROTECTED]>, Iljitsch van Beijnum > <[EMAIL PROTECTED]>, [email protected], JINMEI Tatuya / ???? > <[EMAIL PROTECTED]> > Content-Transfer-Encoding: 7bit > From: Ralph Droms <[EMAIL PROTECTED]> > Subject: Re: [dhcwg] Re: prefix length determination for DHCPv6 > Date: Fri, 17 Aug 2007 12:27:46 -0400 > To: "Hemant Singh (shemant)" <[EMAIL PROTECTED]> > X-Mailer: Apple Mail (2.752.2) > Return-Path: [EMAIL PROTECTED] > X-OriginalArrivalTime: 17 Aug 2007 16:26:47.0602 (UTC) > FILETIME=[685A1920:01C7E0EB] > > Send prefix information, not prefix lengths with assigned addresses. > > The little bit of savings in assuming the tie-in between assigned > addresses and on-link prefixes is short-sighted. > > - Ralph > > On Aug 17, 2007, at Aug 17, 2007,12:23 PM, Hemant Singh (shemant) > wrote: > >> Thanks, James. I agree with Fred then that a node can try DHCPv6. But >> now how does the node get a prefix length? As you are saying, some >> manual or static configuration can be used. I certainly don't like >> the > >> host to assume any prefix length in this scenario. Since I am not a >> fan of any manual configuration, it does make sense, only for such a >> case of absence of an RA, that DHCPv6 provides prefix length. Since >> DHCPv6 doesn't know if the network's router will issue RA's or not, >> then >> DHCPv6 >> has to provide prefix length all the time. >> >> Then I am for what Iljitsch is saying. If a host see a discrepancy in >> prefix lengths from RA and DHCPv6, then host has to decide based on a >> union of information. >> >> Hemant >> >> -----Original Message----- >> From: James Carlson [mailto:[EMAIL PROTECTED] >> Sent: Friday, August 17, 2007 11:49 AM >> To: Hemant Singh (shemant) >> Cc: Templin, Fred L; Iljitsch van Beijnum; [EMAIL PROTECTED]; >> [email protected]; JINMEI Tatuya / ???? >> Subject: RE: [dhcwg] Re: prefix length determination for DHCPv6 >> >> Hemant Singh (shemant) writes: >>> I have not found any information in the ND RFC's nor DHCPv6 RFC that >>> say a node can initiate DHCPv6 if node doesn't receive any RA. I >>> need > >>> to see explicit text in some document to accept what you said below. >> >> It does say this. See RFC 2462 section 4: >> >> The next phase of autoconfiguration involves obtaining a Router >> Advertisement or determining that no routers are present. If >> routers >> are present, they will send Router Advertisements that specify >> what >> sort of autoconfiguration a host should do. If no routers are >> present, stateful autoconfiguration should be invoked. >> >> And then more forcefully in 5.5.2: >> >> 5.5.2. Absence of Router Advertisements >> >> If a link has no routers, a host MUST attempt to use stateful >> autoconfiguration to obtain addresses and other configuration >> information. An implementation MAY provide a way to disable the >> invocation of stateful autoconfiguration in this case, but the >> default SHOULD be enabled. From the perspective of >> autoconfiguration, a link has no routers if no Router >> Advertisements >> are received after having sent a small number of Router >> Solicitations >> as described in [DISCOVERY]. >> >> It's certainly pointless unless you also have access to some static >> prefix information, but it's what the documents say to do. >> >> -- >> James Carlson, Solaris Networking >> <[EMAIL PROTECTED]> >> Sun Microsystems / 1 Network Drive 71.232W Vox +1 781 442 >> 2084 >> MS UBUR02-212 / Burlington MA 01803-2757 42.496N Fax +1 781 442 >> 1677 >> >> _______________________________________________ >> dhcwg mailing list >> [EMAIL PROTECTED] >> https://www1.ietf.org/mailman/listinfo/dhcwg > _______________________________________________ dhcwg mailing list [EMAIL PROTECTED] https://www1.ietf.org/mailman/listinfo/dhcwg -------------------------------------------------------------------- IETF IPv6 working group mailing list [email protected] Administrative Requests: https://www1.ietf.org/mailman/listinfo/ipv6 --------------------------------------------------------------------
