[c-nsp] DHCP Binding Expiration

[Justin Shore]

Manaf Al Oqlah wrote:
> Hi all,
> 
> I am configuring a Cisco 7600 router as DHCP server for my broadband clients. I am using DHCP snooping and ARP inspection for security reasons and the leased time expiration is set for 30 minutes and no excluded-address is configured. The problem is that I still can see  some clients IP addresses lease expiration are Infinite in the DHCP binding! what could be the reason for this behavior and could be this some sort of attack!! 

I get them too.  I never have figured out what causes them.  So far it 
hasn't been a big deal for me.

BTW, I'd recommend not using the IOS DHCP server for anything that more 
than convenience at a very small site.  I would highly recommend 
deploying a server-based DHCP server like ISC DHCPd.  Lots more bells a 
whistles to work with.  Plus you can have redundancy with the 
server-based solution.  The IOS DHCP server is a fairly stripped down 
implementation.  I don't think it was intended to be used in large 
environments like a SP's broadband network.

Justin