Layer 2 Protocol Tunneling; Layer 2 Protocol Tunneling Overview; What You Can Do; What You Need To Know - ZyXEL Communications GS2210 Series User Manual

28.1 Layer 2 Protocol Tunneling Overview

This chapter shows you how to configure layer 2 protocol tunneling on the Switch.

28.1.1 What You Can Do

Use the Layer 2 Protocol Tunnel screen
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.

28.1.2 What You Need to Know

Layer 2 protocol tunneling (L2PT) is used on the service provider's edge devices.
L2PT allows edge switches (1 and 2 in the following figure) to tunnel layer 2 STP (Spanning Tree
Protocol), CDP (Cisco Discovery Protocol) and VTP (VLAN Trunking Protocol) packets between
customer switches (A, B and C in the following figure) connected through the service provider's
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.
Figure 183 Layer 2 Protocol Tunneling Network Scenario
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, 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).
C
HAPTER

Layer 2 Protocol Tunneling

(Section 28.2 on page
Service Provider's
Network
STP
1
CDP
VTP
GS2210 Series User's Guide
261
262) to enable layer 2 protocol
C
2
2 8