On (04/21/09 01:23), Darren Reed wrote:
> So why do you suppose Microsoft included /release and /renew for the  
> command line of ipconfig? FWIW, they also do automatic renewal.
>
> Doing a manual renew isn't always about "extending" the lease of an  
> address, it can also be a way to...
> * get a new address because the DHCP server has been reconfigured
> * get a new DNS server because the DHCP server has been reconfigured
> * get a new default router because the DHCP server has been reconfigured
> * force an extension of the DHCP interval because I know the DHCP server  
> will be unavailable when it tried to do an automatic renewal
> ...you get the idea.
>
> As well as taking care of change, being able to renew allows me to  
> verify that a change to the DHCP server has worked properly - doing a  
> "delete" and then "create" is likely to be a lot more dramatic and have  
> larger consequences than a renew that works.

In related context, I had a discussion with Erik today about how to
re-trigger DAD on a duplicate address. The kernel has dad restar timers
for IPv4 addresses, and post datapath-refactoring, that feature should
be shared with IPv6 addresses, but in order to administratively
retrigger DAD at any arbitrary time, Nevada allows the admin to
attempt to set the IFF_UP on the address, which will restart dad
for that address. 

Since this is analogous to the dhcp "renew-lease" for static addresses,
we can have a renew-* set of commands for the addreses to reverify
the address.

--Sowmini

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