[DCHPv6] was Re: v6 subnet size for DSL & leased line customers

James R. Cutler james.cutler at consultant.com
Fri Dec 28 02:37:18 UTC 2007

And, besides the list forwarded below,
Designated printers,
Preferred DNS Servers,
and, maybe, more.

Even in a large enterprise, the ratio of "routers" to DHCP servers  
makes control of many end system parameters via DHCP a management win  
compared to configuration of "routers" with this "non-network core"  
data.  (In case I was to abstruse, It is cheaper to maintain end  
system parameters in a smaller number of DHCP servers than in a  
larger number of "routers".)

This is completely separate from the fact that many experienced  
router engineers are smart enough configure routers with NTP server  
addresses in preference to DNS names, and likewise for many other  

The end system population has requirements which respond much more  
dynamically to business requirements than do router configurations,  
which respond mostly to wiring configurations which are, by  
comparison, static.  The statement that DHCP is not needed for IPv6  
packet routing may well be exactly accurate.  The absence of good  
DHCP support in IPv6 has costly consequences for enterprise  
management, of which IP routing is a small part.

You have seen this before from me:  Consider the Customer/Business  
Management viewpoint, not just that of routing packets around between  
boxes.  Pull your head out of your patch panel and look at all the  
business requirements.  If you can show me a more cost effective way  
to distribute all the parameters mentioned here to all end systems,  
I'll support it.  In the meantime, don't use religious arguments to  
prevent me from using whatever is appropriate to manage my business.   
I'll even use NAT boxes, if there is no equivalently affordable  
stateful firewall box!


Begin forwarded message:

> From: Leo Bicknell <bicknell at ufp.org>
> Date: December 27, 2007 7:33:08 PM EST
> To: North American Network Operators Group <nanog at merit.edu>
> Subject: Re: v6 subnet size for DSL & leased line customers
> In a message written on Thu, Dec 27, 2007 at 10:57:59PM +0100,  
> Iljitsch van Beijnum wrote:
>> It is wih IPv6: you just connect the ethernet cable and the RAs take
>> care of the rest. _You_ _really_ _don't_ _need_ _DHCP_ _for_ _IPv6_.
>> If you need extreme control then manual configuration will give you
>> that, which may be appropriate in some cases, such as servers.
> Really.  I didn't know RA's could:
> - Configure NTP servers for me.
> - Tell me where to netboot from.
> - Enter dynamic DNS entries in the DNS tree for me.
> - Tell me my domain name.
> - Tell me the VLAN to use for IP Telephony.
> Those are things I use on a regular basis I'd really rather not
> manually configure.
> -- 
>        Leo Bicknell - bicknell at ufp.org - CCIE 3440
>         PGP keys at http://www.ufp.org/~bicknell/
> Read TMBG List - tmbg-list-request at tmbg.org, www.tmbg.org

James R. Cutler
james.cutler at consultant.com

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