PIX will not get DHCP on outside interface

Unanswered Question
Jan 6th, 2008

I have a PIX501. I am plugging it into a cable modem but it will not get a DHCP address. I have tried power cycling both devices and tried a straight thru and crossover cable but it still will not work. I am sure why... The outside interface is configured with "ip address outside dhcp setroute".

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JORGE RODRIGUEZ Sun, 01/06/2008 - 14:36

Connect to pix either via console of telnet through your inside interface ip.


this should get you up and running.


config t

ip address outside dhcp retry 10

global (outside) 1 interface

nat (inside) 1 0 0

once you have enter this configuration do show interface to see if outside interface has obtained dynanic IP address, and write down the ip address, if you are successfull then you need to place a defaul

route in pix.


route outside x.x.x.x 1

where x is the outside interface IP address.



HMidkiff Mon, 01/07/2008 - 05:45


Thanks for your reply. I tried your suggestion but still didn't get an IP address. I tried both a straight thru and crossover cable and reboot both the modem and PIX, but still nothing. I even called my ISP. Once they heard this was a PIX and not their gear they said they didn't support it. Any other suggestions? Thanks again.

JORGE RODRIGUEZ Mon, 01/07/2008 - 07:41

How is your physical outside interface configured for transmission speed?, if it is hardcoded change it to auto with command interface ethernet0 auto try it and see if that makes any difference in getting an IP.



HMidkiff Mon, 01/07/2008 - 17:13


Thanks again for taking an interest in my issue. I tried resetting the interface but still the same thing. I am quite baffles by this. If I put it on any other network is works fine... If you any other ideas I am all ears...

JORGE RODRIGUEZ Tue, 01/08/2008 - 08:04

hmmm.. what version of code are you running?

if you connect a regular system do you get IP?

HMidkiff Tue, 01/08/2008 - 08:09


Thanks for getting back to me again. The PIX501 is running 6.3(5). Today I am going to pickup a hub, so I can sniff the traffic while the unit is trying to get is IP address. Hopefully this will bring something to light.

bob.bartlett Tue, 01/08/2008 - 08:48

First power off your cable modem for 5 minutes. Then with the 501 powered down restart your cable modem. Once the cable modem is up and lights are normal then power up the PIX.

HMidkiff Tue, 01/08/2008 - 09:16


Thanks for replying to my post. I have tried many combinations of power off's and on's. I will try the 5 minutes as you suggest. Thanks.

HMidkiff Wed, 01/09/2008 - 05:53


I tried your suggestion but still got the same thing! No IP address on the outside interface on the PIX501. I tried both a straight thru and crossover but not difference. I then put a hub in the middle and sniffed the wire while the PIX501 was trying to get its IP. I saw the "discovery" packets broadcasting out but never saw an offer come back. I am very puzzled at this point. The modem is a WebStar. I am going to check their site for any info on this. I cannot imagine any special caveats when it comes to DHCP....


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