48-Port T3/E3 CEM Interface Module Configuration Guide, Cisco IOS XE 3S (Cisco ASR 900 Series)
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- Updated:
- September 19, 2017
Chapter: Configuring Pseudowire
Configuring
Pseudowire
Cisco Pseudowire Emulation Edge-to-Edge (PWE3) allows you to transport traffic by using traditional services such as T1/E1 over a packet-based backhaul technology such as MPLS or IP. A pseudowire (PW) consists of a connection between two provider edge (PE) chassis that connects two attachment circuits (ACs), such as T1/E1 or T3 /E3 links.
- Information About Pseudowire
- How to Configure Pseudowire
- Additional References for Configuring Pseudowire
Information About Pseudowire
The following sections describe how to configure pseudowire on the interface module of the chassis.
Overview of Pseudowire
Pseudowires manage encapsulation, timing, order, and other operations in order to make it transparent to users. The pseudowire tunnel acts as an unshared link or circuit of the emulated service.
Overview of Circuit Emulation
Circuit Emulation (CEM) is a technology that provides a protocol-independent transport over IP/MPLS networks. It enables proprietary or legacy applications to be carried transparently to the destination, similar to a leased line.
CEM provides a bridge between a Time-Division Multiplexing (TDM) network and Multiprotocol Label Switching (MPLS) network. The chassis encapsulates the TDM data in the MPLS packets and sends the data over a CEM pseudowire to the remote Provider Edge (PE) chassis. As a result, CEM functions as a physical communication link across the packet network.
The chassis supports the pseudowire type that utilizes CEM transport: Structure-Agnostic TDM over Packet (SAToP).
L2VPN over IP/MPLS is also supported on the interface modules.
Overview of Structure-Agnostic TDM over Packet
Structure-Agnostic TDM over Packet (SAToP) encapsulates Time Division Multiplexing (TDM) bit-streams as pseudowires over public switched networks. 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 Provider Edge (PE) chassis. For example, a T1 attachment circuit is treated the same way for all delivery methods, including copper, multiplex in a T3 circuit, a virtual tributary of a SONET circuit, or unstructured Circuit Emulation Service (CES).
In SAToP mode, the interface is considered as a continuous framed bit stream. The packetization of the stream is done according to IETF RFC 4553. All signaling is carried out transparently as a part of a bit stream.
How to Configure Pseudowire
The following sections describe how to configure pseudowire.
Configuring CEM
This section provides information about how to configure CEM. CEM provides a bridge between a Time Division Multiplexing (TDM) network and a packet network, MPLS. The chassis encapsulates the TDM data in the MPLS packets and sends the data over a CEM pseudowire to the remote Provider Edge (PE) chassis.
The following sections describe how to configure CEM.
Configuring CEM Restriction
Not all combinations of payload size and dejitter buffer size are supported. If you apply an incompatible payload size or dejitter buffer size configuration, the chassis rejects it and reverts to the previous configuration.
 Note | CEM interface does not support idle-cas parameter. |
- Configuring CEM Group for SAToP
- Configuring CEM Classes
- Configuring CEM Parameters
- Verifying the Interface Configuration
Configuring CEM Group for SAToP
enable configure terminal controller t3/e3 0/1/0 cem-group 0 unframed end
Configuring CEM Classes
A CEM class allows you to create a single configuration template for multiple CEM pseudowires. Follow these steps to configure a CEM class:
enable configure terminal class cem mycemclass payload-size 512 dejitter-buffer 12 exit interface cem 0/0/1 cem 0 cem class mycemclass xconnect 10.10.10.10 200 encapsulation mpls exit
Configuring CEM Parameters
The following sections describe the parameters you can configure for CEM circuits.
- Configuring Payload Size
- Setting the Dejitter Buffer Size
- Shutting Down a CEM Channel
- Configuring CEM Parameter on CEM Interface
Configuring Payload Size
To specify the number of bytes encapsulated into a single IP packet, use the payload-size command. The size argument specifies the number of bytes in the payload of each packet.
Default payload sizes for T3/E3 interface are:
Default payload sizes for a structured CEM channel depend on the number of time slots that constitute the channel. Payload size (L in bytes), number of time slots (N), and packetization delay (D in milliseconds) have the following relationship: L = 8*N*D. The default payload size is selected in such a way that the packetization delay is always 1 millisecond.
Note | Both payload-size and dejitter-buffer must be configured simultaneously. When you select a value of payload-size, the acceptable range of dejitter-buffer for that payload size is displayed. |
Setting the Dejitter Buffer Size
To specify the size of the dejitter-buffer used to compensate for the network filter, use the dejitter-buffer command. The configured dejitter-buffer size is converted from milliseconds to packets and rounded up to the next integral number of packets. Use the size argument to specify the size of the buffer, in milliseconds. The range is from 1 to 32; the default is 5.
Shutting Down a CEM Channel
To shut down a CEM channel, use the shutdown command in CEM configuration mode. The shutdown command is supported only under CEM mode and not under the CEM class.
Configuring CEM Parameter on CEM Interface
The CEM parameters can be configured directly on CEM interface. Follow these steps to configure CEM parameters:
enable configure terminal class cem mycemclass payload-size 1024 dejitter-buffer 10 exit interface cem 0/0/1 no ip address cem 0 cem class mycemclass xconnect 10.10.10.10 200 encapsulation mpls exit
Verifying the Interface Configuration
Use the following commands to verify the pseudowire configuration:
- show cem circuit—Displays information about the circuit state, administrative state, the CEM ID of the circuit, and the interface on which it is configured. If xconnect is configured under the circuit, the command output also includes information about the attachment circuit status.
Router# show cem circuit ? <0-504> CEM ID detail Detailed information of cem ckt(s) interface CEM Interface summary Display summary of CEM ckts | Output modifiers Router# show cem circuit CEM Int. ID Line Admin Circuit AC -------------------------------------------------------------- CEM0/1/0 1 UP UP ACTIVE --/-- CEM0/1/0 2 UP UP ACTIVE --/-- CEM0/1/0 3 UP UP ACTIVE --/-- CEM0/1/0 4 UP UP ACTIVE --/-- CEM0/1/0 5 UP UP ACTIVE --/--
Router# show cem circuit 0 CEM0/13/1, ID: 0, Line: UP, Admin: UP, Ckt: ACTIVE Controller state: down, T3/E3 state: up Idle Pattern: 0x55, Idle CAS: 0x8 Dejitter: 10 (In use: 0) Payload Size: 1024 Framing: Unframed CEM Defects Set None Signalling: No CAS RTP: No RTP Ingress Pkts: 11060 Dropped: 0 Egress Pkts: 11061 Dropped: 0 CEM Counter Details Input Errors: 0 Output Errors: 0 Pkts Missing: 0 Pkts Reordered: 0 Misorder Drops: 0 JitterBuf Underrun: 0 Error Sec: 0 Severly Errored Sec: 0 Unavailable Sec: 0 Failure Counts: 0 Pkts Malformed: 0 JitterBuf Overrun: 0
Router# show cem circuit summary CEM Int. Total Active Inactive -------------------------------------- CEM0/1/0 1 1 0
Associated Commands
The following commands are used to configure pseudowire:
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cem-group |
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payload-size dejitter-buffer |
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class cem |
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controller t1 |
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xconnect |
Additional References for Configuring Pseudowire
Related Documents
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Cisco IOS commands |
Standards and RFCs
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There are no standards and RFCs for this feature. |
MIBs
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To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL: |
Technical Assistance
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