Thus spake "Iljitsch van Beijnum" <[EMAIL PROTECTED]> > On 24-jul-2006, at 19:04, Stephen Sprunk wrote: >>> DHCPv6 isn't needed today, and the RDNS option makes sure it's not >>> needed in the future where there is no IPv4 RDNS server configured, >>> either. > >> DHCPv6 _is_ needed in many cases today due to devices which require >> options other than RDNS. For instance, many embedded devices need >> TFTP servers to boot. > > :-) > > Are you serious? These days more than enough flash to store an > embedded OS can be had for a buck or so.
Yes, I'm serious. A couple megs of flash are cheap, but the ROM space to update the OS (or download it the first time) is still precious. Also, most cheap embedded devices still need to download things like config files to be useful, regardless of whether the OS is in flash, and the _vast_ majority of devices in the VoIP space do so via TFTP. Ditto for things like thin clients that boot via PXE+TFTP. I'd love for TFTP to go away and be replaced with something like HTTP, but when you compare the code size, it's no contest. And then we'd need a new option to specify an HTTP boot URL :-) >> Forcing them to implement a DHCPv6 client just to get one option >> seems wasteful, given part of the justification for the RDNS option >> is to remove DHCPv6 from beefy devices like PCs. > > If you really think this is useful then go ahead and define something > using RAs, but I think the days of tftp booting are over. And > certainly server-wise, if you can run a tftp server you can run a > dhcpv6 server. In fact, the need to have routers that support the > tftp boot option could be a deployment issue here. In my particular case, the TFTP server is managed by a different entity than the DHCP server, so they're not interchangeable. Think Vonage -- all those little $25 boxes get addresses via a local DHCP server (or static config), but they grab software and config files from a distant server across the Internet. >>> The difference between DNS and these others is that EVERY general >>> purpose host connected to the internet needs to have DNS servers >>> configured, while this isn't true for the other protocols, and/or the >>> server for these other protocols is much less dependent on the >>> connectivity of the host at any given moment in time. > >> Not all the world is a PC running a web browser. Lots of embedded >> devices have no use for DNS. > > So what kind of communication do they engage in? I've seen devices that do nothing more than send SNMP traps to a particular IP address, respond to NTP queries, or exchange X11/RFP/RDP with a server. In my particular case, the device may need RDNS if its servers were configured as hostnames, but if the admin configures the server as an IP address (the normal case), it has no need for RDNS. While one can argue it's useful for a toaster to support DNS, is it actually _mandatory_? Is TCP even mandatory if the toaster can get what it needs via UDP? >> I don't see why there's resistance to importing either specific >> DHCP options or the entire lot into the RA, rather than limiting >> ourselves to RDNS. > > I don't have insurmountable problems with this, but this not the > issue under consideration right now, the RA option for DNS > configuration is. And my answer to that is that this draft solves only a subset of the problem. If the consensus is that a RDNS-only draft should be advanced, that's fine, but I hope there will be similar support for the next dozen RA options that import other DHCP options the same way. S Stephen Sprunk "God does not play dice." --Albert Einstein CCIE #3723 "God is an inveterate gambler, and He throws the K5SSS dice at every possible opportunity." --Stephen Hawking -------------------------------------------------------------------- IETF IPv6 working group mailing list ipv6@ietf.org Administrative Requests: https://www1.ietf.org/mailman/listinfo/ipv6 --------------------------------------------------------------------
