[141869] in North American Network Operators' Group
Re: The stupidity of trying to "fix" DHCPv6
daemon@ATHENA.MIT.EDU (Jimmy Hess)
Sun Jun 12 21:43:20 2011
In-Reply-To: <20110613012918.GA47336@ussenterprise.ufp.org>
Date: Sun, 12 Jun 2011 20:42:33 -0500
From: Jimmy Hess <mysidia@gmail.com>
To: nanog@nanog.org
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On Sun, Jun 12, 2011 at 8:29 PM, Leo Bicknell <bicknell@ufp.org> wrote:
> DHCP today uses an exponential backoff if there is no response, I don't
> see why that can't be kept in IPv6. =A0Plus I wonder how long users would
> keep on machines that get no useable network connectivity.
>
> I really think the number of broadcast packets is a total non-issue.
Rather than deem it a non-issue; I would say The impact of broadcast packet=
s
depends on the network they are transmitted over.
If you have a Layer 2 domain with 50000 hosts on it; the number of per-hos=
t
broadcast packets will be much more important than if you have a broadcas=
t
domain with 1000 hosts.
This could have been (but was unfortunately not) mitigated in the v6 specs =
by
adding options to DHCPv4 to configure IPv6 address and gateway at the same
time IPv4 configuration is received, in lieu of using v6 based
protocols for config;
Requiring configuration to be grabbed _two_ times per host is inefficient -=
- ONE
DHCP discovery for every host on the LAN (either RA+DHCPv6 or DHCPv4) would
be more efficient.
If v6 hosts are dual stack, and v4 information is already pulled from
DHCP.... how much
sense does it really make to need a second discovery process to find a v6 s=
erver
to config the host, particularly when there exists possibility of
conflicting options; DHCP
can config some non-interface-specific things such as time zone, hostname,=
etc.
There is a potential for greater issues on networks where the number
of broadcasts
may not have been an issue for IPv4; the IPv6 broadcast messages
have a larger
payload, because there are 96 more bits in an IPv6 address than an
IPv4 address.
The broadcasts for configuring IPv6 are incurred _on top_ of the broadcas=
ts
already existing for IPv4 on a dual stack network, since IPv6 hosts
still have to config
IPv4 simultaneously.
--
-JH
