Layer 2 Protocol Tunneling; Layer 2 Protocol Tunneling Overview; What You Can Do; What You Need To Know - ZyXEL Communications GS1920-24 User Manual

27.1

Layer 2 Protocol Tunneling

This chapter shows you how to configure layer 2 protocol tunneling on the Switch.
Layer 2 protocol tunneling (L2PT) is used on the service provider's edge devices.
27.1.1

What You Can Do

Use the Layer 2 Protocol Tunnel screen (Section 27.2 on page 228) to enable layer 2 protocol
tunneling on the Switch and specify a MAC address with which the Switch uses to encapsulate the
layer 2 protocol packets by replacing the destination MAC address in the packets.
27.1.2

What You Need to Know

Layer 2 protocol tunneling (L2PT) is used on the service provider's edge devices.
L2PT allows edge switches
Protocol), CDP (Cisco Discovery Protocol) and VTP (VLAN Trunking Protocol) packets between
customer switches
network. The edge switch encapsulates layer 2 protocol packets with a specific MAC address before
sending them across the service provider's network to other edge switches.
Layer 2 Protocol Tunneling Network Scenario
Figure 166
A
STP
CDP
VTP
B
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,
and B, you can enable protocol tunneling on edge switches
Protocol), LACP or UDLD (UniDirectional Link Detection).
C

Layer 2 Protocol Tunneling

(1 and 2 in the following figure)
(A, B and C in the following figure)
Service Provider's
Network
STP
1
CDP
VTP
GS1920 Series User's Guide
227
HAPTER
Overview
to tunnel layer 2 STP (Spanning Tree
connected through the service provider's
C
2
1 and 2 for PAgP (Port Aggregation
2 7
such as A