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switch to firewall communication issues

I have a cat 4006 connected to a PIX 525 on the DMZ interface. the PIX is running IOS vers 6.1. The 4000 is running cat os 5.5.(10) at layer 2 and IOS version 12.0(14)W5(20) on the router card (WS-X4232-L3). For the past three days I've been noticing a strange behaviour. All networks reachable through the DMZ interface of the PIX go down. When I log in the switch and then session into the routing module I cannot ping the firewall interface on the DMZ side. From the firewall, I also cannot ping the router interface of the switch. The two devices are in the same vlan. In the arp table of the cat, I see the mac address of the firewall, but the firewall does not have an entry for the

router's mac. From the router, I can ping the standby firewall. From the primary firewall I can also ping the standby. After I do "clear arp" everything starts working fine till it happens again. When the problem occurs, I notice that I can reach any other device residing on the same IP segment as the DMZ interface of the firewal. The only device I cannot reach is the router interface on the DMZ ip segment. I've already eliminated issues such as bad cables, loops and duplicate ip addresses. I also tested the intervlan communication integrity of the switch when the outage occurs. Everything checked out ok. Does anyone have an idea what this could be? At this point I believe the problem has to do with

Thanks for your input.


Re: switch to firewall communication issues

You can try disabling VTP pruning on the switch and see if that solves the problem.