OlenCom MG-iP Series User manual

MG-iP-
TDM Over IP Gateway
October 2006
Copyright © 2006 OlenCom Electronics ltd.. All rights reserved.
Specifications and information are subject to change without notice.

MG-IP – TDM Over IP Gateway Reference Manual
MG-IP Reference Manual
Notice Page
Release Information
Date Rev. Change Level Comments Catalog No.
June 2006 3.3.0 Firmware
version 3.3.0 Revised with additional information on CLI, RCP, and
other subjects
DC-RM-MG-IP-
1/MG-IP-4
October 2006 3.4.0 Firmware
version 3.4.0 Revised with additional information on Clock Recovery,
Download Files, Corrections to a
number of incorrect CLI examples
DC-RM-MG-IP-
1/MG-IP-4
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MG-IP – TDM Over IP Gateway Reference Manual
About this Document
The MG-IP-1 and MG-IP-4 units are fully integrated TDM over Packet (TDMoP) gateways that
multiplex T1/E1 circuits and 100 Mbps user Ethernet data ports onto any standard Ethernet/IP network
or link. The units support rapid design of standards-compliant TDM over packet circuit emulation
equipment. They can be used in standalone applications or in hosted environments. The MG-IP-1,
which supports a single E1/T1 port only, is targted as a CPE device and is limited to a single
pseudowire session, while the MG-IP-4 provides support for 4 E1/T1 ports and may be configured as
an aggregator, aggregating multiple pseudowires opposite multiple MG-IP-1 devices. This document
describes the functionality, pinout, power requirements, and management of the MG-IP-1 and the MG-
IP-4. Loopback mechanisms and troubleshooting suggestions are also provided.
The MG-IP-1 and MG-IP-4 feature identical software and board layouts. All CLIs
and management options are exactly the same on both modules. While many of
the examples in this manual focus on the MG-IP-1, they are equally applicable to
the MG-IP-4.
Further Reading
If you would like further information about the MG-IP-1 and MG-IP-4, or if you have questions not
answered by these documents, please contact [e-mail] or visit our web site at
http://www.olencom.com.
Feedback
We welcome feedback on our products and our documentation.
If you have any comments or suggestions about this product, contact your supplier and give them the
product name and a concise explanation.
Alternatively, you can send your feedback directly to us at [e-mail] with the following
information:
The document title
The document’s catalog number
The page number(s) to which your comments refer
Your comments

Contents i
Table of Contents
1Functional Description.....................................................................................11
Overview......................................................................................................................... 11
Circuit Emulation Service (CES)..................................................................................... 11
MG-IP CES Operation...................................................................................................12
MG-IP in CES Topology................................................................................................12
Fractional Operation ....................................................................................................... 12
CAS Signaling.................................................................................................................12
Grooming.........................................................................................................................12
CCS Signaling.................................................................................................................12
Header Options...............................................................................................................12
Timing Modes ................................................................................................................. 13
Classic TDM Timing.......................................................................................................14
Loopback Timing............................................................................................................14
Internal Timing................................................................................................................14
External Timing...............................................................................................................15
Line Timing......................................................................................................................15
Differential Timing ..........................................................................................................16
Recovered Clock Mode.................................................................................................17
Adaptive Timing..............................................................................................................17
Cascading Two Modules...............................................................................................21
Recovered Timing Holdover.........................................................................................22
Packet Delay Variation (Jitter) Buffer..........................................................................22
Packet Reordering .........................................................................................................22
Interfaces........................................................................................................................ 22
IP Address Configuration..............................................................................................23
WAN IP Configuration Limitations ...............................................................................24
DHCP Option Support...................................................................................................24
Functional Block Diagram............................................................................................... 26
T1/E1 to Packet..............................................................................................................26
Packet to T1/E1..............................................................................................................26
LAN to WAN....................................................................................................................26
WAN to LAN....................................................................................................................27
Ethernet Configuration...................................................................................................27
Control Processor...........................................................................................................27
UART.............................................................................................................................. 27
LED Interface.................................................................................................................. 28
MG-IP Configuration....................................................................................................... 28

MG-IP TDM Over IP Gateway Reference Manual
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Pseudowire Sessions...................................................................................................... 28
Configuration Database.................................................................................................. 28
WAN.................................................................................................................................28
LAN/Management (rear panel).....................................................................................29
T1/E1 Interface...............................................................................................................29
TDM over Packet Application ......................................................................................... 30
Packet Headers .............................................................................................................. 30
CAS Signaling with CESoPSN and CESoEth Headers.................................................. 31
Jitter Buffer/Underrun/Overrun ....................................................................................... 32
Replacement Frames and Packet Reordering...........................................................33
Jitter Buffer Operation....................................................................................................33
End-To-End Delay Calculation.....................................................................................34
Bandwidth per Pseudowire...........................................................................................34
Framing and Signaling Options ...................................................................................... 35
Clocks ............................................................................................................................. 35
LED Interface.................................................................................................................. 36
LEDs ............................................................................................................................... 37
TDM and Pseudowire Error Handling............................................................................. 38
System Overview............................................................................................................38
TDM Defects and Failures............................................................................................38
Status Indications...........................................................................................................43
Error Handling.................................................................................................................46
Application Signaling......................................................................................................52
Errored Second Counters.............................................................................................53
CES Configuration Parameters....................................................................................53
References......................................................................................................................53
2Management Options.......................................................................................55
The Command Line Interface (CLI)................................................................................ 55
CLI Script Files................................................................................................................55
Script File Format...........................................................................................................55
TLV Files......................................................................................................................... 57
TLV Structure..................................................................................................................57
Rules of Construction ....................................................................................................58
SNMP.............................................................................................................................. 60
Automatic Management and Provisioning...................................................................... 60
Safe Download (UDL) Mode.........................................................................................60
File Download via TFTP Client.....................................................................................60
Dynamic Downloading/Processing of CLI Script-based Configuration..................61
Dynamic Firmware Download through a TFTP/DHCP Client..................................61
Syslog Error Reporting..................................................................................................61

Contents iii
3Configuring The MG-IP via CLI........................................................................65
Configuring the Management PC ................................................................................... 66
TELNET Using LAN........................................................................................................ 68
Managing Users.............................................................................................................. 68
User Management Tasks..............................................................................................69
Manage User Accounts Example ................................................................................... 70
Managing the CONSOLE Interface ................................................................................ 74
CONSOLE Management Tasks...................................................................................75
CONSOLE Management Example..............................................................................75
Managing Basic Functionality......................................................................................... 75
Basic Board Management Tasks.................................................................................76
Global Configuration Status............................................................................................ 81
Managing LAN and WAN Interfaces............................................................................... 83
LAN/WAN Management Tasks....................................................................................83
Ethernet Interface Information......................................................................................84
Sample Ethernet Configuration....................................................................................89
Managing the T1/E1 Interface ........................................................................................ 91
T1/E1 Management Tasks............................................................................................92
T1/E1 Interface Information..........................................................................................93
T1/E1 Example Configuration......................................................................................... 99
Managing the MG-IP unit.............................................................................................. 103
Sessions and Pseudowires.........................................................................................103
Out of Stream Signaling..............................................................................................103
Default Configuration...................................................................................................105
Getting Started..............................................................................................................106
Session Management Tasks in Unstructured Mode...............................................116
Session Management Tasks in Structured Mode....................................................118
Structured Mode Example 1 – CESoPSN................................................................121
Structured Mode Example 2 – MEF-8 (CESoEth)...................................................123
Managing SNMP........................................................................................................... 125
SNMP Management Tasks.........................................................................................125
Request Managers.......................................................................................................127
Trap Managers .............................................................................................................128
4SNMP Support.................................................................................................131
The Management Model............................................................................................... 131
SNMP Management Information Base (MIB) ............................................................... 132
MG-IP SNMP Support................................................................................................... 133
MIB Support.................................................................................................................. 133
Standard MIBs..............................................................................................................133
Draft MIBs......................................................................................................................135

MG-IP TDM Over IP Gateway Reference Manual
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Private MIBs..................................................................................................................137
Irregular Functionality..................................................................................................138
Private MIB - General Definitions ................................................................................. 141
MIB Relations................................................................................................................ 141
SNMP Request Manager Configuration ....................................................................... 142
Configuration Sequence ............................................................................................... 142
Pseudowire Creation with Assigned DS-1 Port .......................................................142
Pseudowire Creation with Assigned Timeslots........................................................142
Updating DS1 Parameters..........................................................................................143
Updating the Pseudowire’s Attached Timeslots......................................................144
Setting SNMP Trap Destination.................................................................................144
Upgrading the Software Image...................................................................................145
Traps............................................................................................................................. 145
Default SNMP Settings................................................................................................. 145
Complete Configuration Examples............................................................................... 145
Unframed Pseudowire.................................................................................................146
Framed Pseudowire.....................................................................................................147
5Command Line Interface................................................................................149
How to Access the CLI.................................................................................................. 151
Connecting via the CONSOLE Port...........................................................................151
Connecting via Telnet and a Network Interface.......................................................151
CLI Command Description Conventions....................................................................... 152
CLI Command Hierarchy .............................................................................................. 153
Summary of CLI Commands ........................................................................................ 155
Configuration Commands ...........................................................................................155
Clock configurathion ....................................................................................................155
Ethernet Configuration Commands (LAN & WAN)..................................................156
T1/E1 Configuration Commands................................................................................156
Port Configuration Commands...................................................................................156
Profile Definition Commands......................................................................................157
CONSOLE Configuration Commands.......................................................................157
SNMP Configuration Commands...............................................................................157
TDM over Packet Configuration Commands............................................................157
TDM Error Reporting Commands..............................................................................158
Session Configuration Commands............................................................................159
General Configuration Commands............................................................................159
Monitoring Commands ................................................................................................159
Ethernet Monitoring Commands (LAN and WAN)...................................................160
T1/E1 Monitoring Commands.....................................................................................160
Port Monitoring Commands........................................................................................160

Contents v
Profile Definition Monitoring Commands ..................................................................161
CONSOLE Monitoring Commands............................................................................161
SNMP Monitoring Commands....................................................................................161
TDM over Packet Monitoring Commands.................................................................161
Session Configuration..................................................................................................161
General Monitoring Commands.................................................................................162
Diagnostics Commands ..............................................................................................162
Admin Commands........................................................................................................163
User Commands...........................................................................................................163
CLI Command Descriptions.......................................................................................... 163
6Testing the MG-IP...........................................................................................165
Loopback Options......................................................................................................... 165
Using the Get Status Command to Evaluate Performance.......................................... 168
Troubleshooting Guide.................................................................................................. 169
Appendix A CLI Commands ...........................................................................A-1
CLI Command Lookup Matrix........................................................................................A-1
CLI Command Descriptions...........................................................................................A-5
AddNewSession...........................................................................................................A-5
AddRequestManager...................................................................................................A-6
AddTrapManager .........................................................................................................A-7
AddUser.........................................................................................................................A-8
ApplyChanges...............................................................................................................A-9
Bert...............................................................................................................................A-10
CalibrateJitter..............................................................................................................A-11
ChangePassword.......................................................................................................A-12
ConfigHeaderCESoETH............................................................................................A-13
ConfigHeaderSAT/CESoP........................................................................................A-14
ConfigSesTargetIP.....................................................................................................A-15
ConnectClockToSession...........................................................................................A-16
DeleteUser...................................................................................................................A-17
DownLoadFile.............................................................................................................A-18
ForceUserLogout........................................................................................................A-19
FunctionalTest............................................................................................................A-20
GetActiveUsers...........................................................................................................A-21
GetBertStatus .............................................................................................................A-22
GetBoardData.............................................................................................................A-23
GetCLIPrompt.............................................................................................................A-24
GetClockStatus...........................................................................................................A-25
GetConfig.....................................................................................................................A-26
GetConfigDBStatus....................................................................................................A-31

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GetConfigIfs................................................................................................................A-32
GetConfigUarts...........................................................................................................A-33
GetDateTime...............................................................................................................A-34
GetDefGateway..........................................................................................................A-35
GetFirmwareStatus....................................................................................................A-36
GetGlobalConfig.........................................................................................................A-37
GetGlobalStatus.........................................................................................................A-38
GetInitDnldStatus.......................................................................................................A-41
GetMacAddress..........................................................................................................A-42
GetModifiedConfigPorts............................................................................................A-43
GetRequestManagers................................................................................................A-44
GetRequestTrapPorts................................................................................................A-45
GetRunningConfigPorts ............................................................................................A-46
GetSessionTimeSlots................................................................................................A-47
GetSnmpStatistics......................................................................................................A-48
GetStatistics................................................................................................................A-52
GetStatus.....................................................................................................................A-55
GetStatusBoard..........................................................................................................A-58
GetStatusIfs.................................................................................................................A-59
GetSystemDesc..........................................................................................................A-61
GetTimeSlotMap.........................................................................................................A-62
GetTrapManagers......................................................................................................A-63
GetUsers......................................................................................................................A-64
GetVersion...................................................................................................................A-65
ListClocks....................................................................................................................A-66
ListOfSessions............................................................................................................A-67
PwTDMCfgRtpHdrUsed............................................................................................A-68
Reload..........................................................................................................................A-69
RemoveRequestManager.........................................................................................A-70
RemoveSession .........................................................................................................A-71
RemoveSyslogServer................................................................................................A-72
RemoveTrapManager................................................................................................A-73
RenameSession.........................................................................................................A-74
Replace........................................................................................................................A-75
ReplaceReload...........................................................................................................A-76
SatopSendLBitOnAIS................................................................................................A-77
SetActiveClock............................................................................................................A-78
SetCESappTestMode................................................................................................A-79
SetChannelBandwidth...............................................................................................A-80
SetCLIPrompt .............................................................................................................A-81

Contents vii
SetConfigBitStreamClockingMode ..........................................................................A-82
SetConfigCESClock...................................................................................................A-83
SetConfigCESEmulationType..................................................................................A-84
SetConfigCESIP.........................................................................................................A-85
SetConfigCESPaylength...........................................................................................A-86
SetConfigCESVlan.....................................................................................................A-87
SetConfigEth...............................................................................................................A-88
SetConfigEthFlowControl..........................................................................................A-89
SetConfigEthLimit.......................................................................................................A-90
SetConfigLIUlineBuildout..........................................................................................A-91
SetConfigLIULineCode..............................................................................................A-92
SetConfigLIURxTerm.................................................................................................A-93
SetConfigMPLS..........................................................................................................A-94
SetConfigUART..........................................................................................................A-95
SetDateTime...............................................................................................................A-96
SetDefaultDB..............................................................................................................A-97
SetDefGateway...........................................................................................................A-98
SetDynamicMACLpbk................................................................................................A-99
SetEmulationCircuitID..............................................................................................A-100
SetExternalClockDirection......................................................................................A-101
SetExternalClockFreq..............................................................................................A-102
SetFramedParams...................................................................................................A-103
SetIdlePattern...........................................................................................................A-104
SetIPConfig...............................................................................................................A-105
SetLayer2App...........................................................................................................A-106
SetLFlagPolicy..........................................................................................................A-107
SetLIUDynamicLpbk................................................................................................A-108
SetLIULpbk................................................................................................................A-109
SetLOPSPolicy.........................................................................................................A-110
SetPayloadSuppression..........................................................................................A-111
SetPingEnable..........................................................................................................A-112
SetPortsDisable........................................................................................................A-113
SetPortsEnable.........................................................................................................A-114
SetPortState..............................................................................................................A-115
SetRDPolicy..............................................................................................................A-116
SetRequestPort........................................................................................................A-117
SetRFlagPolicy.........................................................................................................A-118
SetRxEqualizerGainLimit........................................................................................A-119
SetSessionPorts.......................................................................................................A-120
SetSessionTimeSlots...............................................................................................A-121

MG-IP TDM Over IP Gateway Reference Manual
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SetSigIdle..................................................................................................................A-122
SetSyslogDisable.....................................................................................................A-123
SetSyslogEnable......................................................................................................A-124
SetSyslogServer.......................................................................................................A-125
SetTDMoPSessionDisable......................................................................................A-126
SetTDMoPSessionEnable ......................................................................................A-127
SetTrapPort...............................................................................................................A-128
SetUserTimeout........................................................................................................A-129
List of Figures
Figure 1: MG-IP-1/MG-IP-4 Application Example....................................................11
Figure 2: CES Packet Format...................................................................................13
Figure 3: Classic TDM Clocking................................................................................14
Figure 4: Loopback Timing Mode..............................................................................14
Figure 5: Internal Timing Mode................................................................................. 15
Figure 6: External Timing Mode................................................................................ 15
Figure 7: Line Timing ................................................................................................ 16
Figure 8: Differential Timing......................................................................................16
Figure 9: Recovered Clock Mode..............................................................................17
Figure 10: Adaptive Loopback Timing.......................................................................18
Figure 11: Adaptive Line Timing ...............................................................................18
Figure 12: Adaptive Internal Timing.......................................................................... 19
Figure 13: Adaptive External Timing......................................................................... 19
Figure 14: Global External Timing.............................................................................20
Figure 15: Network Timing Mode.............................................................................. 20
Figure 16: Cascading Two MG-IP unitss ..................................................................21
Figure 17: MG-IP-1 Interfaces...................................................................................23
Figure 18: MG-IP-4 Interfaces...................................................................................23
Figure 19: MG-IP-1 Functional Block Diagram .........................................................26
Figure 20: MG-IP-4 Functional Block Diagram .........................................................26
Figure 21: SATOP Header........................................................................................ 30
Figure 22: CESoPSN Header ...................................................................................30
Figure 23: CESoEth Header .....................................................................................31
Figure 24: Signaling Packet Format..........................................................................31
Figure 25: Jitter Buffer Operation..............................................................................33
Figure 26: External Clock Jumpers...........................................................................35

Contents ix
Figure 27: OCXO Jumper Location...........................................................................36
Figure 28: MG-IP – Front Pannel.............................................................................. 36
Figure 29: Point-to-multipoint TDM over Ethernet Pseudowire.................................38
Figure 30: TDM Performance Monitoring..................................................................45
Figure 31: CES Gateway ..........................................................................................46
Figure 32: Loss of Signal Trace Example................................................................. 48
Figure 33: RAI Transfer.............................................................................................51
Figure 34: Loss of Packets........................................................................................51
Figure 35: Standalone Application............................................................................55
Figure 36: T1 Framing, 56K Data Channel............................................................. 104
Figure 37: E1 pcm30 Format ..................................................................................104
Figure 38: Network Management Model.................................................................131
Figure 39: MIB Relations.........................................................................................141
Figure 40: Command Directory Hierarchy...............................................................154
Figure 41: Loopback Test Setup-Single Port..........................................................166
Figure 42: Loopback of the WAN Interface.............................................................166
List of Tables
Table 1: Supported DHCP Options........................................................................... 24
Table 2: Frames Per Packet vs. Jitter Buffer Size ....................................................33
Table 3: Bandwidth Requirements (SATOP Header)................................................34
Table 4: LED Description..........................................................................................37
Table 5: Failure Integration/deintegration Times (Sec)............................................. 42
Table 6: PDH Near-End Failure Hierarchy................................................................42
Table 7: PDH Far-End Failure Hierarchy..................................................................43
Table 8: Relations between PDH Near-End and Far-End Failures........................... 43
Table 9: Status Bit Settings.......................................................................................43
Table 10: Incoming Packet Flow-based Indications..................................................45
Table 11: Structure-agnostic Event Handling............................................................47
Table 12: Structure-aware Event Handling...............................................................49
Table 13: TLV Structure Specification.......................................................................58
Table 14: Syslog Messages......................................................................................62
Table 15: User Groups..............................................................................................68
Table 16: User Management.....................................................................................69
Table 17: CONSOLE Management........................................................................... 75
Table 18: Basic Board Management.........................................................................76

MG-IP TDM Over IP Gateway Reference Manual
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Table 19: LAN/WAN Management............................................................................83
Table 20: Ethernet Configuration Commands...........................................................85
Table 21: T1/E1 Management CLI Commands.........................................................92
Table 22: T1/E1 Configuration..................................................................................94
Table 23: Port Configuration.....................................................................................95
Table 24: Profile Configuration..................................................................................95
Table 25: T1/E1 LIU loopback...................................................................................96
Table 26: PortLIU loopback.......................................................................................97
Table 27: Session01 Default Parameters ...............................................................105
Table 28: Global Configuration Parameters............................................................107
Table 29: List Session Parameters......................................................................... 109
Table 30: Unstructured Session Parameters.......................................................... 111
Table 31: Unstructured Mode Session Management Commands .......................... 116
Table 32: Unstructured Session Parameters.......................................................... 116
Table 33: Structured Mode Session Management Commands .............................. 118
Table 34: Structured Session Parameters.............................................................. 119
Table 35: SNMP Management................................................................................ 125
Table 36:Correlation between dsx1LineType and Framing Mode .......................... 139
Table 37: dsx1SignalMode Functionality ................................................................139
Table 38: Pseudowire PSN Type............................................................................ 140
Table 39: Pseudowire Creation with Assigned DS-1 Port.......................................142
Table 40: Pseudowire Creation with Assigned Timeslots.......................................143
Table 41: Updating DS1 Parameters......................................................................143
Table 42: Updating the Pseudowire’s Attached Timeslots......................................144
Table 43: Setting SNMP Trap Destination.............................................................. 144
Table 44: Upgrading the Software Image ...............................................................145
Table 45: Description of Loopback Modes..............................................................165
Table 46: Reported Jitter Parameters.....................................................................169
Table 47: Observations and Corrections.................................................................171

MG-IP TDM Over IP Gateway Reference Manual
11
1 Functional Description
Overview
The MG-IP-1 and MG-IP-4 are DTM Over IP gateway units for Ethernet/IP networks. They perform
point-to-point (MG-IP-1) or point-to-multipoint (MG-IP-4) emulation of T1 or E1 synchronous circuits
by incorporating TDM bitstreams into packets and transmitting them over packet-switched networks as
streams of packets. These streams are referred to as pseudowires (PW). A pseudowire can transport a
full TDM circuit or a bundle of time slots from a TDM circuit. A MG-IP unit at the opposite side of the
network converts the pseudowires back into a TDM circuit. The TDM over-packet circuit emulation
service (CES) that transforms the TDM circuit to a pseudowire and vice versa uses a dynamic jitter
buffer and clock recovery to deliver consistent performance even over the variable timing of the packet
network. See Figure 1 for a graphical view of a mixed MG-IP-1 and MG-IP-4 application.
In this example, point-to-multipoint topology is used where the MG-IP-1 is the CPE device and the
MG-IP-4 is configured as an aggregator, aggregating multiple pseudowire sessions opposite multiple
MG-IP-1 modules. In the example, fractional T1 circuits, supporting six PBXs at different locations,
are aggregated at a central location. Each pseudowire only uses the bandwidth necessary to support the
needs of an individual customer, instead of a full T1. Adaptive timing is used, with clocking of the
aggregator units based on the accurate timing of the Central Office. Each Slave MG-IP-1 unit performs
adaptive clock recovery from the stream of packets in the pseudowire.
Circuit Emulation Service (CES)
CES refers to the process of creating pseudowires that transport TDM circuits across a packet network.
Since a TDM circuit is bi-directional, the pseudowire CES process is also bi-directional. For example,
at one end of the pseudowire the TDM circuit is broken down into fixed size packets; a header is added
to each packet and the packet is transmitted. At the other end of the packet network, the header is
removed from the packet, and a TDM circuit is re-constructed.
Central
Office Switch
4xE1
MG-iP
Slave
MG-iP
Slave
MG-iP
Slave
MG-iP
Slave
MG-iP
Slave
MG-iP
Slave
Fractional E1
PBX
Fractional E1
PBX
Fractional E1
PBX
Fractional E1
PBX
Fractional E1
PBX
Fractional E1
PBX
PacketSwithed Network
MG-iP
Master

MG-IP TDM Over IP Gateway Reference Manual
12
MG-IP CES Operation
The circuit emulation can be in either unstructured or structured mode. In unstructured mode, the entire
T1/E1 circuit is transferred regardless of the structure of frame and time slot boundaries. This is called
“structure agnostic”. In structured mode, full or fractional frames can be packetized and transferred
between MG-IP units. E1 and T1 data is structured as frames based on an 8 KHz frame sync. Each
frame is divided into 8-bit time slots (32 slots for E1, 24 slots for T1). The traffic is depacketized on
the other side of the packet network to recreate frames with the selected time slots in their
corresponding time slot positions.
MG-IP in CES Topology
The MG-IP-1 can be configured to operate in point-to-point topologyopposite another MG-IP-1. It is
limited to support a single pseudowire. The MG-IP-1 can also operate as a CPE device in point-to-
multi point topology opposite a MG-IP-4 aggregator.
The MG-IP-4 can be configured to operate in point-to-point topology opposite another MG-IP-4, with
support for four pseudowire sessions. It can also operate as an aggregator device in point-to-multipoint
topology opposite MG-IP-4 or MG-IP-1 CPEs. The MG-IP-4 is capable of aggregating up to ten
pseudowire sessions.
Fractional Operation
When a fractional TDM circuit is transported on a pseudowire only the selected time slots are sent.
Even if all the voice channel time slots on a port are sent, frame synchronization is not transmitted with
the voice channel data. E1 time slot 0 (zero) and the T1 F bit are not transmitted. Rather, frame
synchronization is recreated at the receiving end of the pseudowire.
CAS Signaling
In structured mode, TDM circuits that use channel associated signaling (CAS) carry this information
within the TDM stream. Circuits in E1 format carry this information in time slot 16. Circuits in T1
format carry channel signaling in one bit of each channel in one out of every six frames in a super
frame. Signaling information can optionally be sent either through a separate pseudowire or within the
same pseudowire in a separate stream so that the signaling can be inserted in the recreated TDM frame
in the appropriate place according to the signal type. When fractional TDM is transported on a
pseudowire, the MG-IP units utilize the minimal Ethernet WAN bandwidth required for transmitted
time slots by transmitting only the selected time slots and by sending signaling out-of-stream.
Grooming
A single TDM circuit can be divided up into multiple pseudowires. A group of time slots can be sent to
a port on one target MG-IP unit and another group of time slots from the same circuit can be sent to a
port on the same or on a different MG-IP units.
This functionality is only applicable to the MG-IP-4 and grooming is supported only when the MG-IP-
4 is configured as an aggregator.
CCS Signaling
Common Channel Signaling and other signaling methods that use a dedicated channel, such as PRI and
BRI, are supported transparently by the MG-IP-1 and MG-IP-4. The dedicated channel is included in
the list of time slots assigned to the pseudowire and is transmitted at all times with the voice channels.
This approach assumes that each group of voice channels has its own signaling channel.
Header Options
Pseudowire packets have headers that are used to define the connection between a pair of MG-IP units.
The MG-IP units support standard header encapsulation as specified in IETF-PWE3 SAToP/CESoP

MG-IP TDM Over IP Gateway Reference Manual
13
and MEF-8. Three packet header formats are supported: the SAToP (structureagnostic TDM over
packet) header for unstructured data, the CESoPSN (circuit emulation service over packet switched
network) header for structured data and the CESoEth (circuit emulation service over ethernet) header
as defined by the Metro Ethernet Forum (MEF-8) format. The CESoEth header can be used for either
structured or unstructured circuits. See Packet Headers section.
All standard protocol headers include control information to be exchanged between the pseudowire
peer, and provide status information such as alarms and defects occurring on the TDM interface.
Figure 2: CES Packet Format
Timing Modes
The Circuit Emulation Service enables convergence and transport of TDM circuits (E1/T1) over
packet-switched networks. To do so, it must feature a mechanism capable of maintaining and keeping
the TDM clock synchronized between peers of a pseudowire, in order to maintain E1/T1 circuit clock
continuity across the packet network, and to meet the standards of ITU G.823 and G.824.
To achieve this requirement, Olencoms’ products have been designed to support a variety of timing
modes, including:
Loopback timing
Internal timing
External timing
Line timing
Recovered timing (adaptive/differential timing)
Differential timing
Changing the timing mode will require to reset the MG-IP unit.
MG-IP units only support a Single Clock Domain. It is the customer’s
responsibility to feed the CES device with TDM ports, all of which are timed by
the same clock source (this applies to the MG-IP-4 only).

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Classic TDM Timing
As shown in Figure 3, in classic TDM clocking, the TDM clock is contained in and recovered by the
TDM data bit in the received bit.
Figure 3: Classic TDM Clocking
Loopback Timing
In loopback timing mode (see Figure 4), TDM ports on the MG-IP (CES device) use the clock received
from the TDM equipment as a transmit clock to the TDM equipment.
In a multipe E1/T1 module (i.e. the MG-IP-4), it is the customer’s responsibility to feed the MG-IP
device with TDM ports, all of which are timed by the same clock source.
Figure 4: Loopback Timing Mode
Internal Timing
In internal timing mode (see Figure 5), TDM ports on the MG-IP (CES device) use the on-board
internal clock (Stratum-4 compatible local oscillator OCXO or TCXO) as a transmit clock to the TDM
equipment.

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Figure 5: Internal Timing Mode
External Timing
In external timing mode (see Figure 6), TDM ports on the MG-IP (CES device) use the external clock
(received through the external clock pin) as a transmit clock to the TDM equipment. The frequency of
the external clock may differ from that of the T1/E1 clock, in which case the units translates and
derives the TDM clock from the external clock frequency received.
If the external clock is disconnected, the MG-IP automatically switches to the onboard TCXO/OCXO.
Figure 6: External Timing Mode
The folowing clock ferquencies are supported:
External clock frequency Derived TDM port frequency
T1 T1
E1 E1
10.24MHz T1
10.24MHz E1
16.384MHz T1
16.384MHz E1
Line Timing
In line timing mode (see Figure 7), TDM ports on the MG-IP (CES device) use the clock received on
port 1 as a transmit clock for all ports. The clock is also exported to the external clock pin (if so
configured). Should the clock on port 1 fail or the port be disabled, automatic switchover to the Free
Running clock 1ppm (TCXO/OCXO) occurs. As soon as the failure condition ends, the MG-IP device

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will revert to the original clock source (line timing mode is not applicable to the MG-IP-1 as it features
only a single E1/T1 port).
Figure 7: Line Timing
Differential Timing
Differential timing (see Figure 8) is designed to deliver the phase variations of the service clock
relative to a common reference clock, so that the receiver can reconstruct the service clock by
replicating these variations. This scheme assumes the availability of stratum-1 traceable common
reference clock on both ends.
The sender generates an RTP timestamp based on a common reference clock, and sampled every fixed
number of service clock cycles (normally equivalent to one packet size). The RTP timestamp delivers
the phase information about the TDM service clock, compared to the common reference clock.
The receiver captures and analyzes the RTP timestamp, and detects the sender’s frequency and phase
shift.
Figure 8: Differential Timing
ReceiverSender
Timestamp
Generator
Differential
Clock
Recovery
Common
Clock
Common
Clock
Local
Clock
TDM
Clock
Recovered
TDM
Clock
RTP
timestamp
In differential timing mode, there are no logical master and slave entities. Each
side of the pseudowire is a sender of a pseudowire packet carrying the RTP
timestamp and performing diferrential timing clock recovery (DCR) on the
pseudowire received with the RTP time stamp. As such, the limitation of a single
session per port (on the “slave”) is no longer valid.
The following common clock/RTP time stamp frequencies are supported:
TDM Clock EXT Clock RTP Time stamp TDM Clock EXT Clock RTP Time stamp
T1 1544MHz 25M E1 2048MHz 25M

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10.24MHz 10.24M 10.24MHz 10.24M
16.384MHz 16.384M 16.384MHz 16.384M
Recovered Clock Mode
In recovered clock mode (see Figure 9), the clock is recovered from the CES packet stream received
from the packet-switched network using two mechansims: adaptive timing algorithm or differential
timing algorithm.
The mechanisms differ as follows: in adaptive timing, the recovery mechanism is based on the rate of
the packets received from the PSN, while in differential timing, it is based on the RTP time stamp
included within the packet and the existance of a reference clock on both sides of the pesudowire.
All ports are clocked according to the recovered clock of one of the sessions (PWS).
It is possible to configure a primary/secondary pesudowire. The clock recovery mechanism uses the
primary pseudowire for the clock recovery algorithm and may manually be switched to the secondary
pseudowire either if the primary one fails or autmatically, when the primary pseudowire is manually
disabled.
The defaults primary and secondary pseudowires are the first and second created sessions, respectively.
A configuration option enables switching from the primary to the secondary and vice versa.
It is possible to change the configuration of either the primary or secondary pseudowire when it is the
currently active clock recovery channel. Clock recovery first switches to the backup pseudowire and,
once the active pseudowire becomes the new backup pseudowire, it can be modified.
If the active pseudowire is manually disabled, clock recovery automatically switches to the alternate
pseudowire, if configured and enabled (if the active pseudowire is the primary one, it will attempt to
move to the secondary pseudowire, while if the active pseudowire is the secondary one, it will attempt
to switch to the primary pseudowire). If no alternate pseudowire is enabled, it will switch to the internal
clock.
Figure 9: Recovered Clock Mode
Figure 9 presents an example of a clock recovered through adaptive timing.
Adaptive Timing
Adaptive timing is applicable to point-to-point and to point-to- multipoint (aggregation) topologies.
This mode defines two logical CES device configurations, as follows:
Master – can be configured to line, external and internal timing
Slave – is always configured to “recovered timing”