Cisco Systems WSC2960XR48FPSI

•Theswitch does not support Layer 2 protocol tunneling on ports with switchport mode dynamic auto

ordynamic desirable.

•DTPis notcompatible with layer2 protocoltunneling.

•Theedge switches on the outbound side of theservice-provider network restore the proper Layer 2

protocoland MAC address information and forward the packets to all tunnel and access ports in the

samemetro VLAN.

•Forinteroperability with third-partyvendor switches,the switchsupports a Layer2 protocol-tunnel

bypassfeature. Bypass mode transparently forwards control PDUs to vendor switches that have different

waysof controlling protocol tunneling. When Layer 2 protocol tunneling is enabled on ingress ports on

aswitch, egress trunk ports forward the tunneled packets with a special encapsulation. If you also enable

Layer2 protocol tunneling on the egress trunk port, this behavior is bypassed, and the switch forwards

controlPDUs without any processingor modification.

•Theswitch supports PAgP,LACP, and UDLD tunnelingfor emulated point-to-point network topologies.

Protocoltunneling is disabled by default but can be enabled for the individual protocols on IEEE 802.1Q

tunnelports oron accessports.

•Ifyou enable PAgP or LACP tunneling, we recommend that you also enable UDLD on the interface for

fasterlink-failure detection.

•Loopbackdetection is not supported on Layer 2 protocol tunneling of PAgP, LACP,or UDLD packets.

•EtherChannelport groups are compatible with tunnel ports when the IEEE 802.1Q configuration is

consistentwithin an EtherChannelport group.

•Ifan encapsulated PDU (with the proprietary destination MAC address) is received from a tunnel port

oran access port with Layer 2 tunneling enabled, the tunnel port is shut down to prevent loops. The port

alsoshuts downwhen aconfigured shutdownthreshold for theprotocol is reached.You can manually

reenablethe port (by entering a shutdown and a no shutdown command sequence). If errdisable recovery

isenabled, the operation is retried after a specified time interval.

•Onlydecapsulated PDUs areforwarded tothe customernetwork. The spanning-treeinstance running

onthe service-provider network does not forward BPDUs to tunnel ports. CDP packets are not forwarded

fromtunnel ports.

•Whenprotocol tunneling is enabled on an interface, you can set a per-protocol, per-port, shutdown

thresholdfor the PDUs generated by the customer network. If the limit is exceeded, the port shuts down.

Youcan also limit BPDU rate by using QoS ACLs and policy maps on a tunnel port.

•Whenprotocol tunneling is enabled on an interface, you can set a per-protocol, per-port, drop threshold

forthe PDUs generated by the customer network. If the limit is exceeded, the port drops PDUs until the

rateat which it receives them is below the drop threshold.

•Becausetunneled PDUs (especially STP BPDUs) must be delivered to all remote sites so that the customer

virtualnetwork operates properly, you can give PDUs higher priority within the service-provider network

thandata packets received from the same tunnel port. By default, the PDUs use the same CoS value as

datapackets.