Welcome to ISAserver.org

Comcast DHCP renewal problems

Users viewing this topic: none

Logged in as: Guest

Printable Version

All Forums >> [ISA Server 2000 Firewall] >> General >> Comcast DHCP renewal problems

Page: [1]

Message

<< Older Topic Newer Topic >>

Comcast DHCP renewal problems - 16.Jun.2002 2:33:00 AM

zifnab

Posts: 8
Joined: 6.Apr.2002
Status: offline

Hello,

It appears as though Comcast within the past 3 days or so has changed something with my service. All of my DHCP leases are set to expire in one hour of being obtained.

I have packet filters set up just as explained here in the article about how to set up dynamic ip DHCP Client Filter with the 0.0.0.0 address and the address of the DHCP server.

Still I am having problems, everytime my lease expires my server won't renew it until I reboot. I see blocked packets coming in with param#1 = 67 and param#2 = 68 about every 3 minutes from what I believe is my cable modem's IP address? It appears as though the address my isa server is assigned is different from my cable modem which is also different from the dhcp server i see in ipconfig /all. Does anyone know what packet filters I can set up to make it so I don't have to reboot my server every hour? I've tried all kinds of different filters and nothing seems to work.

The only solution I can possibly think of is to write a schedule batch file to do ipconfig /renew which works to cause my lease to never expire. but that to me is not a solution. I would rather be able to do ipconfig /release and then ipconfig /renew which doesn't work right now..

thanks.

Post #: 1

Featured Links*

RE: Comcast DHCP renewal problems - 17.Jun.2002 7:15:00 AM

tshinder

Posts: 47663
Joined: 10.Jan.2001
From: Texas
Status: offline

Hi Zifnab,

You'll need to schedule an ipconfig /renew *before* the lease expires. If you end up with 0.0.0.0, then you have to stop the firewall service to get a new lease.

HTH,
Tom

(in reply to zifnab)

Post #: 2

RE: Comcast DHCP renewal problems - 19.Jul.2002 3:47:00 PM

mboczek

Posts: 81
Joined: 13.Jun.2002
From: Corunna, Ontario
Status: offline

I think you'll find that the /renew results in a DHCPNACK from the ISP. This causes the NIC to drop the lease, it should then apply for another lease. Unfortunately ISA can't handle this (see MS Q287673).

I believe Tom's last reply was "Some ISP's don't follow the rules".

More unfortunately it's their option. One solution is a hardware router between ISA and the Cable Modem. You'll find a few postings on this subject.

(in reply to zifnab)

Post #: 3

RE: Comcast DHCP renewal problems - 22.Jul.2002 2:00:00 AM

mboczek

Posts: 81
Joined: 13.Jun.2002
From: Corunna, Ontario
Status: offline

My last reply was a bit terse. I've been having the same DHCP renewal problem since June 1st, and getting just a bit peeved with my ISP.

The firewall/router is a Linksys, got one today works fine. Check out Forum: ISA Server General; Installation; Topic: "Cable modem router" for a fuller description. (Search for "linksys")

(in reply to zifnab)

Post #: 4

RE: Comcast DHCP renewal problems - 22.Jul.2002 7:02:00 AM

tshinder

Posts: 47663
Joined: 10.Jan.2001
From: Texas
Status: offline

Hi Malc,

The router solution is a good one, as long as it has the smarts to do one to one NAT. You can use it with it a dynamic DNS service and take advantage of publishing too!

Thanks!

Tom

(in reply to zifnab)

Post #: 5