ZyXEL Communications GS2220 Series - Layer 2 Protocol Tunneling; L a Ye R 2 Pro to C O L T Unne Ling; Layer 2 Protocol Tunneling Overview; What You Can Do

Chapter 31 Layer 2 Protocol Tunneling
GS2220 Series User’s Guide
296
C HAPTER 31
La ye r 2 Pro toc o l Tunne ling
31.1 La ye r 2 Proto c o l Tunne ling O ve rvie w
This chapter shows you how to configure layer 2 protocol tunneling on the Switch.
31.1.1 Wha t You C a n Do
Use the La ye r 2 Pro to c o l Tunne l screen (Section 31.1 on page 296) 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.
31.1.2 Wha t You Ne e d to Kno w
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.
Fig ure 226 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