Hi there. I have an odd problem and I need some troubleshooting assistance.
I have an office network configured as 192.168.0.0/16 and we have hosts configured in various ranges in that large subnet. Most server are 192.168.0.0/16 and others are 192.168.5.0/16 (treated kind of like they are in /24 subnets. I have a Microsoft DHCP server assigning addresses in the 192.168.3.0/16 space (again, treated like /24). All of my servers and hosts have a /16 subnet mask, and the default gateway is configured as 192.168.0.1.
Here's my problem: Whenever a host receives a DHCP address from my MS DHCP server, it can only ping certain servers and hosts in the 192.168.0.0/16 space. For instance, the host can ping anything in 192.168.5.0 and 192.168.3.0 but has troubles in the 192.168.0.0 range. I've double checked the DHCP server and I know it's giving out the proper subnet mask, and I've verified that with a packet sniffer on the host. Whenever the host tries to ping the gateway, or anything beyond the gateway, the pings timesout. Other hosts can ping the box, but the switch can't ping it.
When I look at the arp table on both the host and switch (Catalyst 4500) I can see that both are receiving the correct MAC addresses from ARP requests. And the most interesting thing, when I turn on ICMP debugging on the switch and start a continuous ping from the host, I can see ICMP echo replies the switch is sending back to the host, but nothing ever actually gets there.
I don't have DHCP snooping or dynamic arp inspection turned on. I can't think of anything else on the switch side of things to look at. Any ideas?
Thanks in advance,