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Configuration Note 9. Pseudo Wires
Version 6.8 29 Mediant MSBR
9 Pseudo Wires
Pseudo wires is a mechanism that emulates the essential features of a native service,
while transporting over a Packet Switched Network (PSN), where the mechanism tunnels
traffic through a PSN.
Services emulated can include T1, E1 leased line, frame relay, Ethernet, ATM, TDM, or
SONET/SDH.
The Pseudo Wires mechanism does the following:

Provides a true end-to-end solution for operators

Transforms the access network, by tightly integrating it with the core

Provides a platform for new services (such as Virtual Private LAN Service), and not
just for the transport of legacy services
9.1 Connectivity Fault Management (CFM)
IEEE 802.1ag Connectivity Fault Management (CFM) refers to the ability of a network to
monitor the health of a service delivered to customers as opposed to just links or individual
bridges.
CFM protocol provides pseudo wires capability – simulating cross network connectivity. In
case one end point is down, the other end point reflects this failure as well.
The IEEE 802.1ag CFM standard specifies protocols, procedures, and managed objects to
support transport fault management. This allows for the discovery and verification of the
path, through bridges and LANs, taken by frames addressed to and from specified network
users and the detection, and isolation of a connectivity fault to a specific bridge or LAN.
Ethernet CFM defines proactive and diagnostic fault localization procedures for
point-to-point and multipoint Ethernet Virtual Connections that span one or more links. It
operates end-to-end within an Ethernet network. CFM provides the capability for detecting,
verifying and isolating connectivity failures in such networks.
CFM does the following:

Monitors the health of links (because providers and customers might not have access
to the management layer)

Checks connectivity of ports

Detects frame structure failures

Avoids security breaches
9.2 Commands
The table below describes the Ethernet CFM commands:
Table 9-1: Ethernet CFM Commands
Command Description
MSBR# configure data
Enter the data configuration menu.
(config-data)# ethernet cfm
aging-time [1-9999]
Configures the remote MEP aging time.
Maintenance End Point (MEP) is located at
the edge of the domain. It defines the
boundary for the domain. A MEP sends and
receives CFM frames through the relay
function, drops all CFM frames of its level or
lower that arrive from the wire side.