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New Member

PIX 501 and cable modem connection

I am trying to connect my pix 501 to my cable modem at home and pix is not able to obtain a DHCP address from the ISP (Rogers Cable in Toronto).

I have the following command for the outside interface.

ip address outside dhcp setroute

when I captured the packets using the sniffer, at my end I can only see "dhcp discover" packets from the pix and there is no traffic back from the ISP. According to the ISP they see their DHCP server sending out the "dhcp offer" packets back to the pix, which I dont see at my end.

When I use my laptop, there is no problem in obtaining dhcp address from the ISP. Therefor ISP is concerned the cable modem is working fine and they don't want to help me troubleshoot any futher.

Also, just to make sure my pix NIC is working, I setup a DHCP server internally and there is no problem obtaing the IP address. So I am assuming my pix config and NICs are working fine!!

anyone has any idea to why my pix was not able to obtain IP address from the ISP?????

Thanks in advance.


Re: PIX 501 and cable modem connection

Hi, I have seen this problem also and I had to release my IP address from my W2K box first, then put the PIX in place and boot it up.

Hope that helps....

New Member

Re: PIX 501 and cable modem connection

Actually I have capability to obtain 2 IP address from the DHCP server (cost me extra $10). I have also tried the release/renew on my w2k box.


Re: PIX 501 and cable modem connection

Are you looking at the "show interface" command after the PIX boots up? Or are you having problems getting out to the internet after the PIX is up and running?

New Member

Re: PIX 501 and cable modem connection

My pix's external interface is not obtaining any IP address from the ISPs dhcp server.

If I do a "show IP" the ip address for the external interface is

If I do a "debug dhcp" and try the release/renew command, "ip address outside dhcp setroute", getting "dhcp command failed" you think there could be bug on the pix OS version 6.1???


New Member

Re: PIX 501 and cable modem connection

Have you tried rebooting the cable modem? I know that when I want to switch my cable connection from my PC to my laptop, I have to power off the cable modem before it will allow me to get an address. I'm thinking that the cable modem is somehow caching my MAC address, or using something similar to port security on a catalyst switch to only allow 1 host to connect.

If I don't reboot, after a half an hour or so I can get an address.

New Member

Re: PIX 501 and cable modem connection

borrow the spare unit from the ASP lab to determine if it's an issue with your unit or i can lend you mine

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