DHCP code in 2.0.4+

Phil Mayers p.mayers at imperial.ac.uk
Mon Jun 8 18:49:18 CEST 2009

Alexander Clouter wrote:
>> Is anyone actually using that? What advantages does it have over the 
>> stateless auto-configuration protocol? (i've not really done that much 
>> reading as regards to IPv6 yet).
> Problem with stateless is that in the long run (for organisations) I 
> doubt people will use it.  Why, RFC3041.  Second reason, in the IPv6 
> world it's expected that you have *several* IPv6 addresses (mobile IPv6, 
> local-link, SCTP gets exciting too here).  It's going to make it awkward 
> to deal with user accountability when most systems are built around the 
> concept that the user has one IPv4 address...yet alone in addition 
> several IPv6 addresses some of which vary over time.

Stateful IPv6 (aka DHCPv6) is not there yet. There are numerous, serious 
problems with the IPv6 RFCs, in particular the exact semantics of the 
M/O bits. There is much discussion (some informed, some clueless) in the 
IETF mailing list archives, if you want to waste a day.

> I think that's why a lot of organisations are not keen on stateless IPv6 
> address assignment but are keener on DHCPv6.  I personally would just 
> like an event driven (no SNMP polling...) method that lets me log 
> address<->MAC address usage.

Whilst polling is awkward, event-driven has disadvantages too; 
specifically, high-rate changes (power outages).

FWIW I changed our ARP polling to use an "expect" script against out 
Cisco 6500s, because the SNMP ipNetToMedia table is sloooowwwwww when it 
gets >20k entries, but the CLI table is sorted in hardware-order, and is 
thus fast.

> I would ask for ideas, but this is all getting hugely OT.

Ideas for what?

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