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Adding multiple IP addresses assigned from ISP - Routing problem?

FIFBA asked
Last Modified: 2013-12-14
I am on a T1 line, previously had 1 IP assigned by ISP, just purchased second IP. T1 line comes into our facility and is now plugged into a switch (previously directly to PIX). A PIX is connected to the switch and works fine using previously assigned IP. I am trying to set up another firewall and map to the new IP. Firewall is plugged into switch, and proper IP's and gateway settings have been verified. I am unable to ping the gateway from this new firewall. I am 99% percent sure there is no error in our new setup but unfortunately the ISP is a local company with, let's just say "inexperienced" technicians.  What are possible problems on the ISP's end that I can have them look at? I think there is some kind of routing issue...can someone provide some ideas? 1st IP address and the 2nd IP address are on same subnet, but it is a /24 subnet. Is this a clue?  Is the new IP routed in some kind of way that will not work for our specific needs? All input is appreciated.
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Is the gateway the PIX? Or another device.
Top Expert 2008
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The gateway is NOT the PIX. It is assumed to be the ISP's router.

I agree that the /24 is unusual. This is a small local ISP that undoubtedly does things a little different.  I was very surprised that they actually do not charge for the additional IP address. And we do not have the entire block in the /24 subnet.  The sanitized IP's are as follows:

x.x.x.1 ISP gateway
x.x.x.125 Our PIX
x.x.x.171 Our new firewall (not working).


All IP's on /24 subnet.
Top Expert 2008

Pretty straight forward setup. So you are being handed an ethernet interface. Can you ping the other PIX interface. If you can do that it has got to be on the providers side.


Well, I have the PIX set up to deny external pings so I can't really test that right now...I'm pretty confidant that if it was allowed, that it would be ping fine (would need to change gateway setting on the new router right?). My problem is that I am not sure what to tell the ISP tech...have had trouble with them 'understanding' things in the past and just want to have some leverage with them. I am certain there is no misconfiguration on our end. I have set up a similar config in an environment much more complex than this one...but with a 'real' ISP. What do I have the ISP check?
Top Expert 2008
This one is on us!
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