Enabling DHCPd listen on dynamically generated interfaces

Simon Hobson dhcp1 at thehobsons.co.uk
Tue May 1 15:52:50 UTC 2012

Shankar Bhat wrote:

>1. I've reasonable number (say, 200) of remote clients and if ONE of 
>them flap, I'll end up automatically reload/restart of dhcp service 
>on my Debian.
>Would this impact dhcp services on existing interfaces ?

Yes, while the server is down, it won't be servicing any requests. 
However, for most common configs, the restart doesn't take long.

>2. What is the precise difference between 
>"/etc/init.d/isc-dhcp-server restart and reload options" ?. Am 
>inclined for 'reload', but would love to hear from community.

Have a look at the script - I suspect you'll find they do the same 
thing. I've just looked at a box I run with 4.1.1 - it doesn't have 
reload, but it does have force-reload which does nothing different to 
restart. In any case, the daemon itself does *not* have a reload 

>3. Are there any other/ better ways to address above scenarios ?

Have you considered using a relay agent instead ? That way you can 
keep the server running. I don't think you'll be able to run one 
relay agent per client connection because of the need for each one to 
listen on the connection to the server.

BTW - what is the interface type that's dynamically generated ? I'm 
assuming not PPP since I didn't think the ISC server works on those.

Simon Hobson

Visit http://www.magpiesnestpublishing.co.uk/ for books by acclaimed
author Gladys Hobson. Novels - poetry - short stories - ideal as
Christmas stocking fillers. Some available as e-books.

More information about the dhcp-users mailing list