ZyXEL Communications Plumbing Product metrogigabit switch User Manual

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Chapter 29 Layer 2 Protocol Tunneling
MGS3700-12C User’s Guide
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for PAgP (Port Aggregation Protocol), LACP or UDLD (UniDirectional Link 
Detection).
Figure 151   L2PT Network Example 
29.1.1  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 
in 
) 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. 
• The Tunnel port is an egress port at the edge of the service provider's network 
and connected to another service provider’s switch. Incoming encapsulated 
layer 2 protocol packets received on a tunnel port are decapsulated and sent to 
an access port.
1
2
A
B
Service Provider's 
Network
C
D
STP
STP
STP