Chapter 28 Layer 2 Protocol Tunneling
GS2200-24 User’s Guide
246
layer 2 protocol packets with a specific MAC address before sending them across
the service provider’s network to other edge switches.
Figure 121 Layer 2 Protocol Tunneling Network Scenario
In the following example, if you enable L2PT for STP, you can have switches A, B,
C and D in the same spanning tree, even though switch A is not directly
connected to switches B, C and D. Topology change information can be
propagated throughout the service provider’s network.
To emulate a point-to-point topology between two customer switches at different
sites, such as A and B, you can enable protocol tunneling on edge switches 1 and
2 for PAgP (Port Aggregation Protocol), LACP or UDLD (UniDirectional Link
Detection).
Figure 122 L2PT Network Example
28.3.1 Layer 2 Protocol Tunneling Mode
Each port can have two layer 2 protocol tunneling modes, Access and Tunnel.
•The Access port is an ingress port on the service provider's edge device (1 or 2
in Figure 122 on page 246) and connected to a customer switch (A or B).
Incoming layer 2 protocol packets received on an access port are encapsulated
and forwarded to the tunnel ports.
1
2
A
C
Service Provider's
Network
STP
CDP
B
VTP
STP
VTP
CDP
1
2
A
B
Service Provider's
Network
C
D
STP
STP
STP
