Deliver clock-locked X.21/V.11 and V.35 circuits over Ethernet, IP or MPLS networks, including wireless networks. Designed for synchronous services that require locked clocks; a “leased line” over packet networks. Support for copper (UTP) and fibre (SFP) networks and for LACP and UTP. The PacketBand-VX provides reliable, transparent and manageable end-to-end X.21 and V.35 connectivity across packet networks. It can connect to local devices and/or leased lines and is able to provide, take and recover clocks. Circuits can be established 24/7 or in response to requests from the attached equipment via control signals so the circuit is established periodically and on demand. PacketBand also supports Multicast for simplex broadcast applications. Clocks are recovered extremely accurately and can exceed the G.823 Synchronous Interface requirement which is used extensively as the quality guide-line for leased lines.

PacketBand-VX supplies a clear or transparent serial clock-recovered or synchronous “pipe” at speeds to 2.048Mbps across different types of packet networks. It duplicates a traditionally-delivered X.21 or V.35 carrier leased line but uses low-cost and widely available packet networks as the transport medium.

Clocks can be generated from one PacketBand and recovered by the other, ensuring synchronisation and no data slips. The on-board oscillators are very accurate, the standard being Stratum3 with enhanced versions available. This configuration provides synchronised clocks to both ends of the circuit when there is no available clock source at the customer premises. This is a common situation when replacing X.21 and V.35 leased lines as these will have normally provided clock from the carrier’s local exchange. PacketBand can also source clocks in these instances from a centrally located Multicast source.

PacketBand-VX clocking

Control Signal Dialling:
The PacketBand delivers a circuit 24/7 but optionally also has the ability to establish the link in response to a DTE raising a control lead. In an X.21 interface for example, a DTE raising “C” will initiate the PacketBand to establish a pre-configured link to a remote location, presenting the “I” lead to both ends of the link when the circuit is established. Control signals are presented and coordinated at both ends of the circuit. This feature means network capacity is only used when required by
the DTE/application.

PacketBand has the unique feature of supporting Multicast transmission which has three key advantages. Multicast is an efficient method of transporting unidirectional (simplex) traffic from one main transmission location to multiple remote sites. PacketBand has the ability to transmit to a Multicast-enabled router and for remote PacketBands to “join” Multicast groups.
This optional facility, together with the PacketBand’s excellent clock recovery accuracy, makes the system ideal for broadcast applications. The Multicast capability also means that the PacketBand can separate the clock recovery data from the bulk user data. This means larger networks with multiple “hops” can deliver not only improved clock synchronisation, but there are network design/loading/QoS and resiliency benefits as well. 3.3 X.21 and V.35 leased lines are normally provided with the clock coming from the carrier network. The Multicast feature means all customer sites can be easily synchronised, particularly where no clock source is available at the end user site. When delivering clocked services to customer sites the Multicast feature ensures all customer sites are clock-locked/synchronised.

PacketBand-VX diagram

Clocking and clock-recovery is a critical area for this type of technology and one in which the whole PacketBand range excels. The method of clock recovery (patent pending) uses a variety of methods depending upon the network type. These work in conjunction with a number of sophisticated intelligent algorithms which calculate any necessary adjustments to the clock based on an algorithm. These algorithms allow users to “tune” the clock recovery to the characteristics of the packet network; after all, networks can differ greatly – an extreme example being the differences between the Public Internet and a private managed network with Quality of Service (QoS). The result is very accurate and stable clocks and a robust system which handles “problems” in the network quickly and reliably.

Ethernet and Packet Handling:

  • Support for 10/100/1GE.
  • Support for packets up to 10,240 bytes in size.
  • Single MAC and IP address, Default Gateway and SubNet Mask, support for DHCP. Disordered packets are reordered automatically.


  • TDM packets can be assigned IP Diffserv (DSCP) or ToS and 802.1p CoS values.
  • PacketBand supports full 802.1q tagging and the associated 802.1p CoS prioritisation levels.
  • All egress packets including TDM links can be prioritised across four output queues using CoS (802.1p) or Diffserv/ToS values.

VLAN Handling
PacketBand’s powerful and latest-generation on-board packet switch offers advanced 802.1Q VLAN facilities such as multiple TAGing, TAG insertion/removal, port routing based on default TAG or a Global TAG table. Egress packets can be TAGed, have multiple TAGs or be stripped of TAGs according to configuration. PacketBand also supports Provider Mode whereby customer packets are TAGed for transport across the network with the TAGs being removed before passing back to the customer at the far end.

Link Aggregation Control Protocol (LACP)
This powerful feature enables two or more Ethernet ports connected between PacketBand and the network switch to be aggregated together as defined in LACP IEEE 802.3-2005. This aggregation makes it appear as if the multiple links are acting as a single high capacity circuit. Furthermore, it adds a level of redundancy with automatic rerouting.

Rapid Spanning Tree Protocol (RSTP)PacketBand-TDM-4E and TDM-3MC only
RSTP (as defined in IEEE 802.1D-2004) identifies the means to build an Ethernet network which contains physical loops between bridges. This facility enables PacketBands to be connected to more than one network switch via different circuits and to provide an automatic fall-back in the case of a link failure.

Rate Limiting
Individual packet ports can have the traffic capacity restricted in various ways, even though the access is 10/100/1GE. This is particularly useful on the second Ethernet port when connected to user LANs where the main link to the network could be “swamped” by data from attached devices.

PDV (Packet Delay Variation or jitter)
The PacketBand-TDM-VX supports up to 400mseconds of PDV or jitter depending upon configuration parameters. This is normally far in excess of the PDV experienced on private networks and many Internet connections. The jitter buffer can be set in msec granularity and adjusted manually or automatically whilst the circuit is in place, overcoming ‘skew’ at start up time caused by the first packet in the buffer arriving later or earlier than average. The buffer re-orders out of sequence packets. If packets are lost by the network the data to be transmitted to the attached device by PacketBand is user configurable.


PacketBand can be locally or remotely configured using easy-to-use high functionality DbManager GUI software. DbLite is supplied free with each unit. Optionally available are different versions to support requirements for larger or more integrated networks. It is sophisticated but simple to use via an intuitive Graphical User Interface (GUI) which controls, configures and monitors individual units and complete networks, currently Microsoft-based, it can also generate SNMP Traps and Alarms. The DbManager supplied with PacketBand (DbLite) allows control and visibility of a single PacketBand at any one time via a single PC. Other options support multiple real-time work-stations, a network of PacketBands and links, and have additional capabilities such as SNMP Traps & Alarms and continuous polling of devices. A document identifying the differences between DbLite and other versions is available. Used by various organisations with different network sizes - up to and including carriers - versions of DbManager deliver a networkwide view of all PacketBands and links via a 4-layer “tree-structured” overview. The status of all PacketBands and links are easy to identify with Alarms being colour coded and passed up the tree. Separate windows provide Event and Alarm information with the ability for operators to add comments etc. Different access levels and
passwords provide operators with appropriate capabilities within the program. An option to encrypt the management traffic across the packet network is available, together with a key management and update system.


A. Clock Recovery
Advanced algorithms tunable for different network characteristics as standard. Capable of exceeding G.823 Synchronous Interface requirements (subject to network performance)

B. TDM port V.35

  • “M-Rack” 37 pin female DCE
  • “M-Rack” 37-pin male DTE
  • RS530 25-way “D” connector
  • Speeds from 64kbps to 2.048Mbps

C. TDM port X.21/V.35

  • 15-way “D” female DCE
  • 15-way “D” male DTE
  • RS530 25-way “D” connector
  • Speeds from 64kbps to 2.048Mbps

D. Ethernet Interfaces

  • 2 x RJ45 UTP
  • 10/100/1GE
  • Auto-sensing or manual
  • Optional SFP cage (module not supplied) for various fibre modes
  • 1 network and 1 or 2 user ports


E. Local Management Port

  • RJ12
  • Asynchronous
  • Auto-sensing to 115kbps
  • Also remote access via packet network

F. Oscillator Performance*

  • Hold-over 24hrs 0.5ppm
  • Aging per day 20ppb
  • Temperature Stability 0.600ppm


  • Hold-over 24hrs 4ppb
  • Aging per day 0.5ppb
  • Temperature Stability 14ppb


  • Hold-over 24hrs 10ppb
  • Aging per day 0.3ppb
  • Temperature Stability 10ppb

(* Figures based on typical parts and performances. Individual oscillators may vary slightly either way. Temperature Stability range -5DegC to +70DegC assumes 20 minutes from power on. Aging and holdover at constant temperature)

G. IP & MAC Address

  • Single MAC address, IP address, subnet mask and default gateway
  • Support for DHCP

H. Configuration
Held in non-volitile memory

I. Power (AC)

  • Internal via IEC connector
  • Auto-sensing 96VAC-240VAC
  • Max consumption 0.2Amps RMS @230VAC
  • MTBF 400,000hrs

J. Power (DC)

  • 1. Nominal -48VDC, 4mm terminal block, -33VDC to -75VDC, 0.35A max, MTBF 1,790,000hrs
  • 2. Nominal -24VDC, 4mm terminal block, -18VDC to -75VDC, 0.55A max, MTBF 800,000hrs

K. Dimensions & Environment

  • Metal chassis and front/rear panels
  • W – 225; D – 200; H – 44mm
  • Weight – 0.9Kg/2lb
  • Optional 19” rack-mount kit; 1 unit per 1U or 2 units side-by-side per 1U
  • Operating Temperature -20°C to +55°C
  • Humidity 10-90% non-condensing

L. Maintenance
There are no serviceable parts or maintenance required. Real-time battery-backed clock life in excess of 7 years.

M. Approvals

  • EMC
  • EN55022:1988
  • EN55014:1988
  • EN61000-3-2/3:1995
  • AS/NZ CISPR22:2000
  • FCC Part 15(B)
  • RoSH Compliant without the use of exceptions

N. Safety

  • EC EN60950-1:2002
  • ACA TS001:1997
  • ACS/NZ60950:2000
  • AS/NZS3260:1993
  • IEC950

O. Telecomms (optional)

  • TBR12/TBR13
  • TBR4/TBR3
  • TIA/E1A-1S/968
  • TNA117
  • AS-ACIF S006/S016