Introduction To Pwe3 - Huawei quidway s7700 Configuration Manual

Quidway S7700 Smart Routing Switch
Configuration Guide - VPN

6.1 Introduction to PWE3

PWE3 refers to a Layer 2 service-bearing technology on a PSN that emulates basic characteristics
of ATM services, FR services, Ethernet services, low-speed TDM services, and SONET/SDH
services.
Pseudo-Wire Emulation Edge to Edge (PWE3) is a type of end-to-end Layer 2 transmitting
technology. It emulates the essential attributes of a telecommunications service such as ATM,
FR or Ethernet in a Packet Switched Network (PSN). PWE3 also emulates the essential attributes
of low-speed Time Division Multiplexing (TDM) circuits and SONET/SDH.
With the Label Distribution Protocol (LDP) as the signaling protocol, PWE3 emulates various
Layer 2 services (such as Layer 2 data packets) of the Customer Edge(CE) through tunnels such
as the Multiprotocol Label Switch Protocol. PWE3 can also transparently transmit the Layer 2
data of the CEs. This proximate emulation may lead to distortion of TDM data.
Figure 6-1
Figure 6-1 PWE3 framework
The relevant terms defined in the RFC are explained as follows:
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A PW uses VC-type and VC-ID to identify a Virtual Circuit (VC), which is similar to that of
VLL in Martini mode.
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Issue 01 (2011-07-15)
shows the PWE3 framework.
AC
CE1
Provider Edge (PE) device.
Customer Edge (CE) device.
Provider (P): It is a device on the backbone network of a service provider.
Attachment Circuit (AC): It is an unshared link or circuit that connects a CE and a PE. An
AC can be either physical or virtual. The attributes of an AC include the encapsulation type,
MTU, and link interface parameters.
PSN tunnel: One or more PWs can be carried over a PSN tunnel.
Pesudo-Wire (PW): It is a virtual connection. A PW is set up by using the signaling protocol.
VC type refers to the encapsulation type of the VC, such as VLAN or Ethernet.
VC ID refers to the identifier of the VC. The VC ID of each VC with the same type on the
entire PE must be unique.
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PW
PSN Tunnel
PSN
PE1
6 PWE3 Configuration
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PE2 CE2
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