Hi,
Im trying to understand the correct behaviour for the UNI port and l2 tunelling on the ME3400E switch running as a layer2 device. No layer3/mpls on it.
In the setup like below, ME3400E#1 UNI facing port G0/4 has 'dot1q and l2-protocol tunnel' enabled and therefore it changes the MAC address of L2 PDUs it receives from the C2900 to 01-00-0c-cd-cd-d0 It then forwards the packets to ME3400#2. This in order to deliver STP and other L2 PDUs to another C2900 on the other end of the network.
C2900------(802.1q trunk)------[UNI G0/4] ME3400E#1 [NNI]------[UNI G0/1] ME3400E#2
ME3400E#1
interface GigabitEthernet0/4
switchport access vlan 35
switchport mode dot1q-tunnel
switchport port-security maximum 1000
switchport port-security
switchport port-security aging time 8
switchport port-security violation shutdown vlan
storm-control broadcast level bps 1m 800k
storm-control action shutdown
l2protocol-tunnel cdp
l2protocol-tunnel lldp
l2protocol-tunnel stp
l2protocol-tunnel vtp
ME3400E#2
interface GigabitEthernet0/1
switchport trunk allowed vlan 2,35
switchport mode trunk
switchport port-security maximum 1000
switchport port-security
switchport port-security aging time 8
switchport port-security violation shutdown vlan
storm-control broadcast level bps 1m 800k
storm-control action shutdown
The question is: should the UNI port of ME3400E#2 receiving traffic from ME3400E#1 drop or allow L2 PDUs with DST MAC 01-00-0c-cd-cd-d0 ?
Im aware a UNI port will always drop L2 packets, but does it also drop L2 PDUs with the Cisco proprietary MAC 01-00-0c-cd-cd-d0 ?
Tests I have done dont seem to be clear on this point. If we continue the network above by adding another C2900 at the other end in order for QinQ to provide L2 connectivity between both 2900s, traffic flows ok from one 2900 to the other but not STP, CDP, VTP. L2 PDUs will flow and STP will work only when I change the ME3400E#2 UNI port to NNI.
To make it confusing I have aother setup where ME3400E#2 UNI port as shown above is allowing L2 tunelled PDUs and layer2 connectivity including STP, CDP, VTP actually works between two C2900s.
So I would like to understand which version is the correct behaviour and move from there as currently it is very confusing
thanks
Mark
