Re: [mif] Route option for DHCPv6 - next steps?

[Alexandru Petrescu <[e-mail]>]

Le 23/04/2012 15:38, Ted Lemon a écrit :
> On Apr 23, 2012, at 5:31 AM, Arifumi Matsumoto<[e-mail]>
> wrote:
>> I said, "From the access network provider perspective". It is the
>> cost they have to pay that matters to them.
>
> It would help to complete this argument if you unpacked the details
> here.   Why is RA so much more expensive than DHCP in this case?   I
> get the sense that this is obvious to the people who are promoting
> various DHCP route options, but it clearly isn't obvious to people
> who aren't network operators, so more detail is needed.

Let me add a comment here.

One part of the higher expense of RA vs DHCP is the burden of
administrative management.  An operator using RA to configure
RFC4191/4861 default and specific routes needs to put various
configuration data (the contents of radvd.conf) in _each_ access router
on which end user connect.

For an ADSL-type ISP this means to remotely configure, and maintain,
each first-hop router (CPE+1) with different sets of specific routes,
and each such router with a different default route.  It means there are
risks of collision (two specific routes valid at two different points,
upon wrong updates), risks of wrong default routes upon network card
replacement, and so on.

It would be easier to have all the default/specific routes written
centralized on a single (load-balanced?) server and push this data to
the first-hop routers upon request from clients - more coeherence, less
collision risks, higher reusability of specific routes.  It's what DHCP
does: the CPE+1 router is a Relay and the config file is in a unique
DHCP Server.

>> AFAIK, only Windows Vista and above supports RFC 4191 by default,
>> though.
>
> This is not a good argument.   Windows Vista is ancient.   We can't
> define IPv6 in terms of the functionality present in Windows XP.

I have a comment about this, in the ADSL-type ISP case.

The CPE box wouldn't be a Windows machine.  It would be unix, and it
would be a router.  Thus, receiving RFC4191 specific routes from an RA
from CPE+1 would leave it shrugging shoulders.

If one wants to deliver specific routes to a CPE box one would't use
RAs, because routers ignore much of info in them.

Alex

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