Specifications

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Cisco MWR 2941 Mobile Wireless Edge Router Release 3.5 Software Configuration Guide, Cisco IOS Release 15.1(3)MR
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Chapter 23 Configuring Pseudowire
Understanding Pseudowire
• Structure-Agnostic TDM over Packet, page 23-2
• Structure-Aware TDM Circuit Emulation Service over Packet-Switched Network, page 23-2
• Transportation of Service Using ATM over MPLS, page 23-2
• Transportation of Service Using Ethernet over MPLS, page 23-3
Structure-Agnostic TDM over Packet
SAToP encapsulates TDM bit-streams (T1, E1, T3, E3) as PWs over PSNs. It disregards any structure
that may be imposed on streams, in particular the structure imposed by the standard TDM framing.
The protocol used for emulation of these services does not depend on the method in which attachment
circuits are delivered to the PEs. For example, a T1 attachment circuit is treated the same way for all
delivery methods, including: PE on copper, multiplex in a T3 circuit, mapped into a virtual tributary of
a SONET/SDH circuit, or carried over a network using unstructured Circuit Emulation Service (CES).
Termination of specific carrier layers used between the PE and circuit emulation (CE) is performed by
an appropriate network service provider (NSP).
For instructions on how to configure SAToP, see Configuring Structure-Agnostic TDM over Packet
(SAToP). For a sample SAToP configuration, see Configuration Examples for Pseudowire.
Structure-Aware TDM Circuit Emulation Service over Packet-Switched
Network
CESoPSN encapsulates structured (NxDS0) TDM signals as PWs over PSNs. It complements similar
work for structure-agnostic emulation of TDM bit-streams, such as PWE3-SAToP.
Emulation of NxDS0 circuits saves PSN bandwidth and supports DS0-level grooming and distributed
cross-connect applications. It also enhances resilience of CE devices due to the effects of loss of packets
in the PSN.
CESoPSN supports channel-associated signaling (CAS) for E1 and T1 interfaces. CAS provides
signaling information within each DS0 channel as opposed to using a separate signaling channel. CAS
also referred to as in-band signaling or robbed bit signaling.
For instructions on how to configure SAToP, see Configuring Circuit Emulation Service over
Packet-Switched Network (CESoPSN). For a sample SAToP configuration, see Configuration Examples
for Pseudowire.
Transportation of Service Using ATM over MPLS
An Asynchronous Transfer Mode (ATM) over MPLS PW is used to carry ATM cells over an MPLS
network. It is an evolutionary technology that allows you to migrate packet networks from legacy
networks, yet provides transport for legacy applications. ATM over MPLS is particularly useful for
transporting 3G voice traffic over MPLS networks.
You can configure ATM over MPLS in the following modes:
• N-to-1 Cell Mode—Maps one or more ATM virtual channel connections (VCCs) or virtual
permanent connection (VPCs) to a single pseudowire.
• 1-to-1 Cell Mode—Maps a single ATM VCC or VPC to a single pseudowire.
• Port Mode—Map one physical port to a single pseudowire connection.