Peabody <waybackNO784SPAM44@yahoo.com> hath wroth:

>I have a Buffalo WHR-HP-G54 router. On the LAN side I have two
>computers, one Ethernet and one wireless. The WAN side goes to a
>Motorola SB5120 cablemodem and then to Cox Cable.
>
>On the LAN side I have DHCP disabled, and both computers have
>specific IPs assigned. On the WAN side the router obtains a
>24-hour dynamic IP lease from Cox.
>
>Half way through the lease, the router apparently renews it, but in
>doing so drops the internet connection for a while.

That's what happens if Cox decides that your router needs to have a
new IP address. When the Buffalo requests a lease renewal, but Cox
returns a NACK, then the DHCP client in the Buffalo will restart DHCP
negotiation and get a new IP address. It's the change in IP address
that's causing the connection loss. You're not really losing t he
internet connection. However, any session you have running at the
time will be dropped and interrupted.

>I just wondered
>if that's necessary.

Only if Cox fails to appreciate users that setup servers and change IP
addresses to discourage the practice. At one time, SBC would always
issue a NACK for a long term (greater than half lease time) DHCP
renewal along with issuing fairly short (2 hr???) lease times. The
result was that I couldn't maintain a VPN connection for more than an
hour. They stopped doing that after a few months of complaints. At
this time, I think it's a 24hr lease, but they still issue NACK's on
long renewals. Kinda sounds like Cox is doing the same thing, but
with the longer lease time.

>I'm pretty sure that never happened when I had
>one computer connected directly to the cablemodem, and Windows
>handled the DHCP. Couldn't the router just Renew instead of
>starting over?

The router is not in control of the DHCP address pool. It's the Cox
server that decides the lease time, renewal response, policy, etc. All
your Buffalo DHCP client can do is politely ask for a renewal and live
with whatever Cox has in place.

>Or, do I have something set wrong?

I'm making a big assumption as to what's happening. The only way I
know to test this is to sniff the DHCP related traffic between the
modem and router for a few days using WireShark/Ethereal. Use an
ethernet hub (not a switch) to do the sniffing. Leave a laptop
running (disable sleep, standy, hibernate, power save, green) with
Wireshark running to capture only DHCP related traffic. Let it run a
few days and see what happens.

--
Jeff Liebermann jeffl@comix.santa-cruz.ca.us
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558