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Product Overview
PacketBand-TDM-1D delivers a high quality, completely transparent, E1/T1 circuit across different types of packet networks and various clocking options for different types of networks (E1 over IP or TDM over IP).
- Highly-accurate and stable clock recovery processes.
- G.823 Synchronisation levels of accuracy achievable down to 10ppb.
- Precise and steady “hold-over” clock.
- “Tuneable” to different network types.
- Robust, reliable and of professional quality.
- Excellent management, statistics and diagnostics.
- Various clocking options, including Plesiochronous and Asymmetrical.
- Inter-works with other PacketBand family members.
- PacketBand excels in delivering stable and accurately clocked E1/T1 “leased lines” over packet networks and benefit from Patapsco’s excellent support.
Interfaces
- A single E1/T1 interface (user switchable)
- RJ45 120 Ohm or 75 Ohm (user switchable) via converter cable.
- Full E1/T1 (user selectable) or a fractional G.704
- 10/100/1GE UTP (Unshielded Twisted Pair RJ45) interface to the WAN
- A local 10/100/1GE UTP Ethernet port
- Optional SFP cage with the appropriate SFP Module interconnects to a fibre WAN
- RJ12 management port (PacketBand is also manageable across the packet network)
- IEC connector for quality internal AC PSU (DC options available)
Clocking
- Clock recovery, accuracy and stability is key to many TDM applications. This clock recovery performance must be maintained when migrating to an unclocked packet network solution and delivering E1 and T1 over IP services.
- Many types of equipment expect similar performance to that of traditional leased lines which are generally referenced to the G.823 Synchronous Interface mask. The PacketBand ranges are specifically designed and optimised to excel in this area and when used on high-quality networks can meet and exceed the G.823 requirements.
- The clock recovery methods use a variety of mechanisms. These include sophisticated algorithms which allow users to “tune” the performance to match the network characteristics; after all, networks differ greatly – an extreme example being between the public Internet and a private managed networks supporting Quality of Service (QoS).
Clock Algorithms
- The TDM-1D supports three advanced E1 over IP algorithms as standard.
- These are designed and optimised for different network types and within these options are two further settings allowing tighter optimisation.
- PacketBand can be configured to extract the best possible TDM over IP service for any given network.
Clock stability
- Clock frequency stability is an important strength of all PacketBands as many services will require very accurate synchronisation to run correctly (for example mobile backhaul).
- PacketBand can deliver reliable services that clock as well as traditionally delivered leased lines.
Clock Sources and Clocking
Although easy to use and configure, PacketBand offers customers a number of solutions.
- TDM port
Clock can be extracted from the attached user ports.
- Adaptive
Using sophisticated recovery algorithms, clock can be derived from any of the in-coming packet streams from a remote “Master” PacketBand. This allows the “Slave” TDM-1D to adaptively recover this clock very accurately across the packet network, in effect synchronising both devices to a common clock.
- Loop-Timing
In instances where both ends of the circuit have a good quality common clock source.
- Plesiosynchronous – PacketBand-TDM-1E only.
Plesiosynchronous (or plesiochronous) working means the TDM-1E can support multiple clocks and in different directions.
- Asymmetrical Working – PacketBand-TDM-1E only.
PacketBand-1E is able to transmit and receive packets of different sizes down to the individual byte level.
This configuration is used in certain types of networks, mainly wireless, where the transport is clocked at the 64KHz level and where a phenomenon called “beating” can occur.
- Multicast – PacketBand-TDM-1MC only.
support for an innovative out-of-band clocking method via Multicast services. Important advantages for larger networks and some vertical markets such as broadcasting. E1 clocks can be recovered extremely accurately across very large networks yet the bulk of the traffic load (the user data) can be given a low priority.
- Internal
If no external quality clock is available, the TDM-1D can use its internal oscillator.
- Clock Hold-Over
Problems in the packet network can cause an unwanted movement in the recovered clock. To avoid this PacketBand enters a “hold-over” state, maintaining the recovered clock at the last value prior to the problem.
Oscillators
- The oscillator quality when recovering clock is very important. The receive PacketBand running “Adaptive” clocking uses different information and many calculations to ascertain how to modify its on-board oscillator’s output to match the clock of the remote or “master” end.
- It can be seen that the more stable the on-board oscillator, the more stable the recovered E1 over IP clock.
- TDM-1D is fitted as standard with a 1ppm TCXO oscillator.
- A low cost upgrade option to a high quality Temperature Stablised Enhanced Stratum3 TCXO oscillator which is ideal for all but the very most exacting applications.
PDV (Packet Delay Variation or jitter)
- The PacketBand-TDM-1D supports up to 400mseconds of PDV.
- This is normally far in excess of the PDV experienced on private networks and many Internet connections.
- Statistics are available to provide information on usage.
Ethernet and Packet Handling
Prioritisation
- 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.
VLAN Handling
- PacketBand’s powerful and latest-generation on-board packet switch offers advanced 802.1Q VLAN facilities such as multiple TAGing.
Link Aggregation Control Protocol (LACP)
- PacketBand-TDM-1E and TDM-1MC only.
- This powerful feature enables two or more Ethernet ports connected between PacketBand and the network switch to be aggregated together.
- 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-1E and TDM-1MC only.
- RSTP 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. This is particularly useful on the second Ethernet port when connected to user LANs where the main link to the network, carrying the TDM over IP traffic, could be “swamped” by data from attached devices.
Overheads
In order to transport TDM data over the packet network, there is some overhead caused by encapsulating the data inside the packet network protocol
- The Protocol
PacketBand supports a number of different packet network protocols. The user’s choice of a particular network will affect the overall size of packet headers.
- Size of Packet
PacketBand supports a configurable packet size per Link which affects the overhead. Typical overheads are in the 5% to 10% range.
Latency
The total end-to-end latency experienced between two devices using PacketBands is made up of four elements:
- Processing Delay Typical processing delay is less than 1msec.
- Transmit Delay This is typically around the 1msec range.
- Jitter Some packets take more or less time than the average to transit the network. PacketBand buffers the fast packets so as to ensure the slow ones can arrive in time to be used. The amount of buffering is user-configurable and will depend upon the performance of the network. The amount of buffering needed (which equates to latency) is a result of the network, not PacketBand.
- Transit Delay All IP networks have different average transit delays. These vary depending upon a large number of criteria, including the number of “hops” and whether satellites are involved.
- Summary: between any pair of PacketBands the most significant element contributing to latency is jitter within the network.
CESoP Modes
- PacketBand supports both “Structure Aware” and “Structure Agnostic” modes.
- Complies with ITU-T recommendation Y.1413, IETF PWE3 draft standards CESoPSN, SAToP and CES draft IAs from MEF and MFA.
Management
- PacketBand can be locally or remotely configured using Patapsco’s 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 Patapsco units and complete networks.
- It can also generate SNMP Traps and Alarms.
- The version supplied with PacketBand (DbLite) allows control and visibility of a single PacketBand at any one time via a single PC.
- Other DbManager 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 comparing the differences between DbLite and other versions is available.
Further details and specifications are available in the PDFs at the top of this page and when registered.
See also the 4-port, 8 port and 16/32 port PacketBand versions. |
