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a switch in Customer X, Site 1, will build a spanning tree on the switches at that site without considering
convergence parameters based on Customer X’s switch in Site 2. This could result in the topology shown in
the Layer 2 Network Topology without Proper Convergence figure.
Figure 12: Layer 2 Protocol Tunneling
Figure 13: Layer 2 Network Topology Without Proper Convergence
In an SP network, you can use Layer 2 protocol tunneling to enhance the creation of EtherChannels by
emulating a point-to-point network topology. When you enable protocol tunneling (PAgP or LACP) on the
Catalyst 2960-XR Switch VLAN Configuration Guide, Cisco IOS Release 15.0(2)EX1
130 OL-29440-01
Configuring IEEE 802.1Q and Layer 2 Protocol Tunneling
Layer 2 Protocol Tunneling Overview