Introduction To Pwe3; Figure 5-1 Pwe3 Framework - Huawei Quidway S9300 Configuration Manual

Quidway S9300 Terabit Routing Switch
Configuration Guide - VPN

5.1 Introduction to PWE3

This section describes the principle of PWE3.
Pseudo-Wire Emulation Edge to Edge (PWE3) bears Layer 2 services. It emulates the essential
attributes of a service such as Asynchronous Transfer Mode (ATM), Frame Relay (FR), Ethernet,
a low speed Time Division Multiplexing (TDM) circuit, or SONET/SDH over a Packet Switched
Network (PSN).
On a Provider Edge (PE) of a PSN, PWE3 uses the Label Distribution Protocol (LDP) as
signaling, emulates Layer 2 services such as Layer 2 data on the Customer Edge (CE) through
tunnels such as Label Switching Paths (LSPs) or Generic Routing Encapsulation (GRE) tunnels,
and transparently transmits the Layer 2 data between the CEs. This approximate emulation may
cause distortion for the TDM data.
Figure 5-1

Figure 5-1 PWE3 framework

CE1
The terms in the reference model defined in the RFC are explained as follows:
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The PW is an encapsulation bearer channel on PE. A PW is set up by using a specified signaling
protocol. The VC type and VC ID are used to identify a VC, which is similar to that of a Martini
L2VPN.
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Issue 03 (2009-08-20)
shows the framework of PWE3.
AC
PE1
PE: It is an edge device on a provider network.
CE: It is an edge device on a user network.
P: It is a backbone device on a service provider network.
AC: It is the attachment circuit. An AC is an independent link or circuit that connects CE
and PE. The AC attributes include the encapsulation type, MTU and interface parameters
of specified link type.
PSN tunnel: It is short for the packet switched network tunnel.
PW: It is a virtual connection.
VC type: indicates the encapsulation type of a VC. The type can be VLAN or Ethernet.
VC ID: identifies a VC. The VC ID of the VCs of the same VC type must be unique on a
PE.
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PW
PSN Tunnel
PSN
5 PWE3 Configuration
AC
PE2 CE2
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