Overview

The Inverse Multiplexing over ATM (IMA) Emulator application can simulate the inverse multiplexing of an ATM cell stream over multiple physical links and retrieve the original stream at the far-end from these physical links. The multiplexing of the ATM cell stream is performed on a cell by cell basis across the multiple physical links. Traffic source can be sequence number, HDL files (containing packets/frames), flat binary file, user-defined frames (ASCII HEX file), and Ethernet data.

The ATM Inverse Multiplexing technique involves inverse multiplexing and de-multiplexing of ATM cells in a cyclical fashion among links grouped to form a higher bandwidth logical link whose rate is approximately the sum of the link rates. This technique provides an effective method of combining the transport bandwidths of multiple links (e.g., DS1/E1 links) grouped to collectively provide higher intermediate rates. This is referred to as an IMA grouping.

Along with AAL0 and AAL5 IMA supports AAL2 which provides bandwidth-efficient transmission of low-rate, short and variable length packets in delay sensitive applications. AAL2 also provides for variable payload within cells and across cells by using segmentation and reassembly technique. AAL type 2 is subdivided into the Common Part Sublayer (CPS) and the Service Specific Convergence Sublayer (SSCS).

GL's IMA Emulator is available as optional client-server based application with GL's T1 E1 Analysis hardware. GL also offers ATM analysis application for real-time capture and analysis of ATM IMA cells over T1 E1 lines. Please visit ATM Protocol Analyzer page for more details.

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Main Features:

• Performs IMA simulation on up to 16 T1 E1 ports
• ATM links can be created on full or fractional timeslots
• Supports hyper channels with discontinuous (sparse) timeslots
• IMA Frame Length can be set equal to 32, 64, 128, or 256
• Dynamically add/remove (Open/Close) of ATM links without loss in data
• Multiple IMA groups can be created with each group configured with multiple virtual channels for traffic tx/rx
• Generate and verify end to end traffic on each Virtual Channel
• User configurable ATM (AAL 5, AAL 2) Packet size
• Payload traffic generation and verification using Sequence number, HDL file (containing packets/frames), Flat Binary file, and User defined frame (ASCII HEX file) for each Virtual Channel independently
• Transmit and receive Ethernet traffic over T1 E1 links by operating in bridge mode
• Provides detailed statistics for all IMA groups and each Virtual Channel associated with a group
• Provides end to end traffic verification statistics
• Ideal solution for automated testing using command line scripts

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Simulating ATM Inverse Multiplex Groups and Links

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Traffic Generation and Verification

GUI provides options to add virtual channels to IMA groups to perform traffic generation and verification. Tx parameters are used to generate the ATM traffic and Rx parameters are used as reference to verify the received frames. The results of the verification are displayed in Tx/Rx Verification tab. The parameters for each VC are independently set.

The IMA permits transmission and reception of following source/sink types:

• Sequence numbers (1,2,4 or 8 least significant byte first (LSB) or most significant byte first (MSB)) with configurable start sequence numbers and increments
• User defined HEX string frame, which is ASCII based. Can be edited, loaded and saved
• Binary flat files that allows user to provide any random data
• GL *.HDL trace file is GL's packet file format which can be constructed pre-hand or captured using ATM Analyzer
• Network traffic (LAN traffic) - This allows user to receive traffic from Ethernet, convert to ATM traffic and send through T1 E1 line and vice versa. IMA emulator can be configured in bridge mode to establish connection and route traffic between LANs. Priority is set based on source IP address, destination IP address, length, or type of service of the packets received from the Ethernet

Other parameters that can be customized include

• Prefix Header - allows the user to prefix a header at the beginning of the ATM packet to be transmitted
• Duration Spec - defines the duration for which Tx/Rx will be done
• Payload length - defines the ATM packet size. Each link can have its own payload size
• Max CPS length - defines the payload length for CPS(Common Part Sublayer) packet

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IMA Emulator as a Bridge

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Data Verification using Statistics

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Using Command Line

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Resources:

Please Note: The XX in the Item No. refers to the hardware platform, listed at the bottom of the Buyer's Guide, which the software will be running on. Therefore, XX can either be ETA or EEA (Octal/Quad Boards), PTA or PEA (tProbe Units), depending upon the hardware.

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