IBM Server with Ethernet Server Connectivity Module, 6 GB Ethernet ports - Qty 1
Cisco 6509 - Oty 02
Cisco 4948 - Qty 02
Earlier setup: IBM server was connected to 6509-1 and 6509-2 and both switches were connected over a trunk link. Everything worked fine without any error.
New setup: 4948-1 connected to both 6509 and 4948-2 is also connected to 6509-2. This gives an error
%C4K_EBM-4-HOSTFLAPPING: Host 00:21:5E:30:0B:0A in vlan 112 is flapping between port Te1/49 and port Gi1/44
In old setup, server MAC is only learned through 6509-1 port. No spanning-tree blocked ports were on either of switch.
However in new setup, ports from both 4948 towards 6509-2 are in blocked state.
It is clearly a layer 2 loop. How can I avoid it? And why it is not occuring when directly conneting server to both 6509 switches.