Cisco Catalyst 3120 Software Manual page 387

Chapter 16 Configuring IEEE 802.1Q and Layer 2 Protocol Tunneling
Figure 16-4
Figure 16-5
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 SP switch, remote customer switches receive the PDUs and can negotiate the automatic creation of
EtherChannels.
OL-12247-01
Layer 2 Protocol Tunneling
Customer X Site 1
VLANs 1 to 100
VLAN 30
VLAN 30
Switch A
Switch B
VLAN 40
Customer Y Site 1
VLANs 1 to 200
Layer 2 Network Topology without Proper Convergence
Customer X
virtual network
VLANs 1 to 100
Service
provider
Trunk
Trunk
ports
ports
Trunk
Trunk
ports ports
Trunk
Asymmetric link
Cisco Catalyst Blade Switch 3120 for HP Software Configuration Guide
Understanding Layer 2 Protocol Tunneling
Customer X Site 2
VLANs 1 to 100
VLAN 30
Switch C
Switch D
VLAN 40
Customer Y Site 2
VLANs 1 to 200
16-9