Hi Everyone,
We have Juniper EX 4200 as core switch at two sites connected Cisco 2960s and Cisco 3560s (access layer switches). For even-numbered VLANs, one Juniper switch is root bridge and for odd-numbered VLANs, other Juniper switch is the root bridge.
We have Cox and Verizon Metro-E links connecting core switches (Juniper EX 4200 at both sites).
I want to do VLAN load sharing using VSTP but somehow it is not working as expected. I want to pass some VLANs through COX and some through Verizon. When there is any issue with Cox, all VLAN traffic pass through Verizon and vice-versa. RSTP is also enabled on both Juniper switches.
I see MAC flapping in log messages on all Cisco access layer switches when I bring up both Metro-E links together. When only Cox is connected, everything works fine. When only Verizon is connected, everything works fine. But when BOTH COX and Verizon are connected, network gets disrupt and I see MAC flapping on all Cisco switches. All cisco switches are running PVST.
Anybody knows what is happening and why VSTP is not working when both COX and VERIZON Metro-E links are active ?
