nanog mailing list archives
Re: v6 subnet size for DSL & leased line customers
From: sthaug () nethelp no
Date: Thu, 27 Dec 2007 11:57:09 +0100 (CET)
Personally, I'm not a big fan of DHCPv6. First of all, from a philosophical standpoint: I believe that stateless autoconfiguration is a better model in most cases (although it obviously doesn't support 100% of the DHCP functionality). But apart from that, some of the choices made along the way make DHCPv6 a lot harder to use than DHCP for IPv4. Not only do you lack a default gateway (which is actually a good thing for fate sharing reasons) but also a subnet prefix length and any extra on-link prefixes. So even if you do address configuration with DHCPv6 you need RAs for that other information.
Which is probably going to make IPv6 deployment slower in service provider environments.
There's also tons of ways to complicate your life by mixing stateless autoconf and DHCPv6, especially since most systems don't support DHCPv6 unless you install additional software. Last but not least, DHCPv6 has a stateful mode that's appropriate for address assignment or prefix delegation, and a stateless mode that's more efficient for the configuration of information that's not client-specific. Unfortunately, it's up to the client to initiate the desired mode. Then there are the M and O bits in RAs that tell you whether to do DHCPv6 but a number of DHCPv6 aficionados look like they want to ignore those bits.
Again, this is something that's going to slow down deployment in service provider environments. Providers are comfortable with the IPv4 DHCP model (which is definitely not stateless) and many of us would like to keep this.
What this all boils down to is that if you want to deploy DHCPv6 you need to install software on a lot of systems and modify a lot of configurations. If you're going to do all that, it's easier to simply configure this stuff manually. The only downside to that is that it's not compatible with easy renumbering, but then, you need to do more than just automate address assignment to support easy renumbering.
"Configure this stuff manually" may work for a small number of customers. It is highly undesirable (and probably won't be considered at all) in an environment with, say, 1 million customers. Steinar Haug, Nethelp consulting, sthaug () nethelp no
Current thread:
- Re: v6 subnet size for DSL & leased line customers, (continued)
- Re: v6 subnet size for DSL & leased line customers sthaug (Dec 25)
- Re: v6 subnet size for DSL & leased line customers Stephen Sprunk (Dec 25)
- Re: v6 subnet size for DSL & leased line customers Iljitsch van Beijnum (Dec 25)
- Re: v6 subnet size for DSL & leased line customers Leo Bicknell (Dec 26)
- Re: v6 subnet size for DSL & leased line customers Florian Weimer (Dec 26)
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- Re: v6 subnet size for DSL & leased line customers Florian Weimer (Dec 26)
- Re: v6 subnet size for DSL & leased line customers Tony Li (Dec 26)
- Re: v6 subnet size for DSL & leased line customers Iljitsch van Beijnum (Dec 26)
- Re: v6 subnet size for DSL & leased line customers Leo Bicknell (Dec 26)
- Re: v6 subnet size for DSL & leased line customers Iljitsch van Beijnum (Dec 27)
- Re: v6 subnet size for DSL & leased line customers sthaug (Dec 27)
- Re: v6 subnet size for DSL & leased line customers Iljitsch van Beijnum (Dec 27)
- Re: v6 subnet size for DSL & leased line customers sthaug (Dec 27)
- Re: v6 subnet size for DSL & leased line customers Iljitsch van Beijnum (Dec 27)
- Re: v6 subnet size for DSL & leased line customers Mark Smith (Dec 27)
- Re: v6 subnet size for DSL & leased line customers Mark Smith (Dec 27)
- Re: v6 subnet size for DSL & leased line customers Leo Bicknell (Dec 27)
- Re: v6 subnet size for DSL & leased line customers Christopher Morrow (Dec 27)
- Re: v6 subnet size for DSL & leased line customers Iljitsch van Beijnum (Dec 27)
- Re: v6 subnet size for DSL & leased line customers Mark Smith (Dec 27)
- Re: v6 subnet size for DSL & leased line customers Leo Bicknell (Dec 27)