Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. And see here for current known issues.

New Member

MSFC with Secondary Interface IP

I have a Catalyst 6509 with an MSFC, behind a PIX firewall connected to the internet. One of the interfaces on the MSFC (Vlan 10) has two ip addresses (networks) one being a secondary, both being NATed. When I put this configuration on line I can get out onto the internet but cannot get to my "DMZ", outside of PIX, from the inside, where my webservers are located. Thus my local network can't see our webpages while the world can. This configuration worked fine when we were using a 7206 router (separate interface cards) but now won't work with the MSFC. We need to keep Vlan 10 with two networks because internally there are a lot of systems on both networks on one vlan. A third internal network, also NATed, Vlan 20 (no secondary IP) has no problem at all going out seeing everything, including our webserver. What's wrong? How do I get my Vlan 10 to work?


Re: MSFC with Secondary Interface IP

Often times complex troubleshooting issues are best addressed in an interactive session with one of our trained technical assistance engineers. While other forum users may be able to help, it’s often difficult to do so for this type of issue.

To utilize the resources at our Technical Assistance Center, please visit and to open a case with one of our TAC engineers, visit

If anyone else in the forum has some advice, please reply to this thread.

Thank you for posting.

CreatePlease to create content