v6 & DSL / Cable modems [was: Private use of non-RFC1918 IP space (IPv6-MW)]

TJ trejrco at gmail.com
Mon Feb 9 20:11:50 CST 2009


>As I read it, you don't want to use DHCP because "it's an other service to
>fail."  Well, what do you think is broadcasting RA's?  My DHCP servers have
>proven far more stable than my routers. (and one of them is a windows
server
>:-))  Most dhcp clients that keep any state will continue using the
>previously assigned address if the server is unavailable (and nothing else
>is using it.)  Configuring a static address in a DHCP server is a pretty
>trivial task.

Your routers fail frequently?  And does your traffic continue to get
forwarded?  Perhaps through another router?
... which would work the same way in an IPv6 scenario ... with the host
knowing it's address for a period of time (Valid timer), and learning a new
gateway in fairly short order (even sans FHRP).


>My point is simply, this whole mess with RA's should never have been on the
>table.  DHCP has been around and used for years to provide IPv4 hosts with
>an address, gateway, and MANY other configuration options.  It exists
>because (in many cases) hosts need more than just an address.  Yet the
>protocol designers, staunch haters of DHCP, refused to see any value in
DHCP
>for IPv6 and rolled back the clock 3 decades dooming us ALL to repeating
the
>same bull.  DHCPv6 can do everything SLAAC can plus infintely more.  And an
>"it just works" configurationless setup could have been part of the
standard
>instead; yet here we are... nobody 100% happy and a considerable amount of
>work being poured into reinventing the DHCP wheel.

Why is there a problem with RAs being the first step, possibly including
prefix info or possibly just hinting @ DHCPv6?


>Manual static configuration is indeed a pain.  That's why we have DHCP...
>set aside a range of addresses for machines that can move around (client
>workstations, etc.) and a pool of persistant addresses for servers,
>printers, etc. that you want to stay in one place -- some applications
>record addresses instead of names, *sigh*.  Everything is in one, easy to
>manage location.  For an ISP where a lot necessarily has to be manually
>configured, it can be more work, but is still simple -- even in the days of
>the "NOC NOTEBOOK" where only one person could be assigning addresses at a
>time. (we've had web based stuff for years now; feed rwhois directly, 'tho
>not automatic.)
>
>> Isn't remembering stuff what we have computers for?
>
>If you aren't accessing machines by number, why do you care if it always
has
>the same number?  As long as the name always maps to the right number, it
>doesn't matter.
>
>> I have a lot of problems with DHCP and most people don't _need_ it.
>> Still, very many people _want_ it and some people do in fact need it.
>> I have no problem with that, as long as it doesn't lead to the
>> situation where I have to run it.
>
>And I, likewise, don't want the utterly useless "RA" forced on my networks.
>Hosts need much more than just a unique address.  And I don't want to have
>to walk around to every one of them to change anything.

Well, as it stands now the RA isn't useless.  
It, and it alone, provides default gateway information ... from the default
gateway itself.
(I actually think that this is architecturally superior, but that is just my
opinion ... )
((The rest of the info, (addressing or other) can be obtained via RA/SLAAC
or DHCPv6))

Also, it is not true in every case that hosts need a "lot more" than an
address.
In many cases all my machine needs is an address, default gateway and DNS
server (cheat off of v4 | RFC5006 | Stateless DHCPv6).






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