TL-SG2428P User Manual

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User Guide 494

Configuring L2PT (Only for Certain Devices) Overview

Overview

Note:

L2PT is only available on certain devices. To check whether your device supports this feature, refer to

the actual web interface. If L2PT is available, there is L2 FEATURES > L2PT in the menu structure.

L2PT (Layer 2 Protocol Tunneling) is a feature for service providers to transparently

transmit Layer 2 protocol data units (PDUs) between customer networks at different

locations through a public ISP network. Some terminology that is used in this section is

defined as follows:

■ Edge Switch: The switch that is connected to the customer network and placed on the

boundary of the ISP network.

■ UNI: User Network Interface, a port configured on the edge switch which is connected

to the customer network.

■ NNI: Network Network Interface, a port configured on the edge switch which is

connected to the ISP network.

As shown in Figure 1-1, a customer has two local networks which are connected through

the ISP network. When the two customer networks run the same Layer 2 protocol, the

Layer 2 PDUs between them must be transmitted through the ISP network to perform Layer

2 protocol calculation (for example, calculating a spanning tree). Generally, the PDUs of the

same Layer 2 protocol use the same destination MAC address. Therefore, when a Layer 2

PDU from a customer network reaches a edge switch in the ISP network, the switch cannot

identify whether the PDU comes from a customer network or the ISP network and then the

PDU will be discarded. As a result, the Layer 2 PDUs cannot be transmitted through the ISP

network to the other side.

Figure 1-1 L2PT Application

PE1

CE1

CE2

UNI

PE2

ISP Network

Customer Network

NNINNI

Customer Network

To resolve this problem, the ISP network should transparently transmit the Layer 2 PDUs

between the two customer networks. In this case, L2PT feature can be configured on

the edge switches (PE1 and PE2) to allow the Layer 2 PDUs to be tunneled through the

network.

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TP-Link TL-SG2428P | Jetstream 24 Port Gigabit Smart Managed PoE Switch | 24 PoE+ Ports @250W, 4 SFP Slots | Omada SDN Integrated | PoE Recovery | IPv6 | Static Routing | Limited Lifetime Protection