The official standard for 802.1q specified a 'mono-spanning-tree' - a single instance of spanning tree for the entire 802.1q domain, (Common Spanning Tree - CST). Cisco Catalysts (by default) run PVST+ - Per VLAN Spanning-Tree+, this is an instance of spanning tree per VLAN. When connected to third party switches on dot1q trunks that support the mono-STP, the Native VLAN will run CST and Cisco will interoperate with it. Cisco uses a different BPDU Multicast MAC address for its PVST+ so it doesn't interfere with the dot1q CST.
I've concrete case where I will have 2 Catalyst 6500 as backbone switches and standard switches (HP Procurve) as access switches and they're connected with 801.q tagged ports/link.
What I understand: the PVST+ BPDUs of the 6500 will be switched by the access sw because destination Mac @ is not one of the access sw. Then the 2 6500 will do their STP/VLAN as if they were directly connected through a cable. Right? If STP is not activated on Access sw not a big deal because the 2 6500 will manage loop plus I get the stp per Vlan feature. Except that my access switch will not resolve local loop.
If I activate STP on the access switches then they receive the untagged BPDU of the Native VLAN of the 6500 and then they will block one the uplink (if 6500 configured as root and secondary root). Right? Then the PVST+BPDU will be no more switched. So in that case CST will interfere with PVST. No?
We are pleased to announce availability of Beta software for 16.6.3. 16.6.3 will be the second rebuild on the 16.6 release train targeted towards Catalyst 9500/9400/9300/3850/3650 switching platforms. We are looking for early feedback from custome...