ZyXEL Communications P-335 PLUS - V3.60 Guía de usuario descargar pdf (Pagina 239)

XS1920 Series User’s Guide

239

CHAPTER 28

Layer 2 Protocol Tunneling

28.1 Layer 2 Protocol Tunneling Overview

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.

28.1.1 What You Can Do

Use the Layer 2 Protocol Tunnel screen (Section 28.2 on page 240) 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.

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 168 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).

Service Provider's

Network

STP

CDP

VTP

STP

VTP

CDP

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ZyXEL Communications P-335 PLUS - V3.60 Guía de usuario Pagina 239