PIX515E - different public IP networks on the inside

Unanswered Question
Feb 4th, 2008
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Hi all,

Can someone clarify me on an issue I'm about to face:

My PIX515E is about to handle multiple different public IP ranges that are routed on a single cable from an ISP router, for example:

ISP router inside IP /

PIX outside IP /

PIX inside IP /

PIX intf2 IP /

PIX intf3 IP /

The default route would be, without network-specific static routes.

The ISP router would be configured to route both /24 and /24 networks using a single cable towards the PIX outside interface. Will this pose any problems when one of the inside interfaces (intf3) belongs to a completely different network than the PIX outside IP?

How about when a host tries try to access Would the traffic be routed to the ISP router ( which would turn it back towards the PIX or would it be routed directly to the right interface if the access-lists allow it?

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Jon Marshall Mon, 02/04/2008 - 13:16
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As long as the ISP routes both subnet ranges to the outside interface of your pix then you will be fine.

If the 2 network and are on separate interfaces, which they are the pix will route between the 2 interfaces without going to the ISP router. The default route pointing to the ISP router will only be used when the pix does not have a more specific route and in this case it will as the networks are directly connected.




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