ZyXEL Communications XGS4700 Series, Manual

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Chapter 29 Layer 2 Protocol Tunneling
XGS4700-48F User’s Guide
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2 for PAgP (Port Aggregation Protocol), LACP or UDLD (UniDirectional Link
Detection).
Figure 143 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 2
in Figure 143 on page 294 ) 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