We have a Catalyst 2948G-L3 switch as our core switch. On port 12, which is setup to be subnet 10.12.0.0 Subnet mask 255.255.0.0, we show activity, but anyone who is on that subnet is down. Our setup is copper from the 2948G-L3 to a media converter, from media converter out via fiber to a 3Com edge switch. If I take the 2948G-L3 out of the picture and replace it with a 3Com switch I can access anything on that subnet. I then try to connect from the 3Com to the 2948G-L3 via a crossover cable and I can ping from the 3Com and receive replies, but still cannot on the 2948G-L3. I show links and activity, but still everyone on that subnet has not connection to the network. Not sure how this is possible, but we tried configuring another port on the 2948G-L3, but still nothing.
Thanks for any help.