in the lab，IBM Power VM1 ---trunk--Cat 6500--trunk--IBM Power VM2，the VM1 and VM2 have the same vlan id，but now vm1 cant ping vm2.
if change like this :IBM Power VM1----trunk--Cat2950 ---trunk--Cat 6500---trunk--IBM Power VM2,now the vm1 ping vm2 ok。 why？VM‘s OS is AIX。
the CAT6500 IOS is C6sup22-psv-mz.121-26.e8.bin.
