Overview
Asynchronous Transfer Mode (ATM) is a flexible network, which carries voice, video, and data in the same way, i.e. fixed
length cells. It has generated a number of revenue opportunities because of its different classes of service support for
multimedia traffic, efficient bandwidth management for burst traffic, support for LAN/WAN architecture and high performance
via hardware switching.
ATM network basically has two kinds of interfaces i.e. UNI (Interface between ATM User and Public ATM switch) and
NNI (Interface between two Public ATM switches). Similar to the OSI Protocol model, ATM has an ATM Layer as Layer 2, ATM
Adaptation Layer (AAL) as Layer 3 and other higher layers depending on C-Plane, U-Plane or Layer Management Plane. User
information is transferred across U-Plane and signaling messages is transferred across C-Plane. ATM-UNI signaling is used
to create and release SVCs along with a particular QoS attached to it depending bandwidth on demand.
GL's ATM Analyzer is used to analyze and decode different ATM protocols like ATM, AAL2 Protocols (CPS-SDU, SSSAR-SDU,
and SSCS), AAL5 (CPCS), UNI etc across U plane and C plane of UNI and NNI interface. The analyzer is also capable of capturing &
reassembling frames that were transmitted with Inverse Multiplexing. IMA combines up to 8 T1/ E1 links to form a single high-speed
connection with flexible bandwidth options.
GL Communications supports the following types of ATM analyzers:
- Real-time ATM Analyzer (Pre-requisites: GL's field proven E1 or T1 internal cards or USB Laptop E1 or T1 external units,
required licenses and Windows 2000/XP/Vista Operating System)
- Offline ATM Analyzers(Pre-requisites: Hardware Dongle and Windows 2000/XP/Vista Operating System)
ATM Analyzer Main Features
- Displays Summary, detail, hex-dump, statistics, and call trace views.
- Summary View displays Dev #, Time Slot, Frame #, VPI/VCI, PT (Payload Type), HEC, OSF, AAL Type, Frame Type, CID,
LI, CPI, UUI, SSSAR CID and SSCS message type and more in a tabular format.
- Detail view displays decodes of user-selected frames from the summary view.
- Hex dump view displays raw frame data as hexadecimal and ASCII octet dump.
- Statistics view displays statistics based on frame count, byte count, frames/sec, bytes/sec etc for the entire capture data.
- Call trace capability based on UNI signaling parameters, VPI/VCI etc.
- CRC verification for AAL5 carrying packet data.
- Support of various UNI Signaling Protocols i.e. UNI 4.0, UNI 3.1 and UNI Q-2931.
- Supports search and filtering capabilities.
- Ability to configure .ini file for PVC carrying UNI signaling messages to get the proper decoding options
- Capability to export summary view details to comma separated values (CSV) format for subsequent import into a database or spreadsheet.
- Capability to export detail decode information to an ASCII.
- Remote monitoring capability using GL's Network Surveillance System.
Additional features supported by Real-time ATM Analyzer are:
- Captures, decodes, filters, and reassembles AAL-2 and AAL-5 frames
in real-time, from within the ATM cells according to user defined VPI/VCI.
- Recorded raw data can be played back using raw data playback application.
- The following variations are accommodated in the software: inverted or non-inverted data, byte reversal or non-reversal,
with or without inverse multiplexing in ATM (IMA).
- Unscrambling of ATM cells based on SDH X^43 + 1 algorithm.
- Multiple streams of ATM traffic on various T1/E1 channels can be simultaneously decoded with different GUI instances.
- Streams may be captured on the selected time slots (contiguous or non-contiguous) and on full bandwidth.
Additional features supported by Offline ATM Analyzer:
- Trace files for analysis can be loaded through simple command-line arguments
- Multiple trace files can be loaded simultaneously with different GUI instances for offline analysis.
Protocols Supported
The list of protocols that are supported by GL's ATM analyzer are as given below:
- ATM Layer- B-ISDN ATM LAYER SPECIFICATION, ITU-T Recommendation I.361
ATM layer is responsible for transporting the
information in the form of a fixed length cells (53 bytes) across the network using several virtual connections identified by
VPI/VCI values. The connection isn't assigned a dedicated bandwidth. Depending on the QoS of involved parties, the
connection is assigned a bandwidth and traffic is actually sent.
- ATM Adaptation Layer (AAL)
ATM adaptation layer performs the necessary mapping between higher layer
protocols and ATM layer. It multiplexes the higher layer info in the fixed length ATM cells. Because of different quality of
service parameters, different types of AAL starting from AAL0 to AAL5 are defined. AAL0 is nothing but ATM cells itself.
Different classes of service are mapped to individual AAL type.
Among these, GL's ATM analyzer supports AAL0 (raw cells), AAL2, and AAL5 as specified below:
AAL0 is nothing but ATM cells itself
AAL 2- Class B (ITU-T Recommendation I.363.2)
AAL 5- Class C & D (ITU-T Recommendation I.363.5)
AAL includes the following sublayers :
- SSCS (Service Specific Convergence Sublayer): ITU-T Recommendation I.366.2
It uses AAL2 connection for transporting different narrowband traffic like Voice, CAS bits, DTMF digits, circuit mode and
frame mode data etc.
- SSSAR (Service Specific Segmentation and Reassembly Sublayer) : ITU-T Recommendation I.366.1
It multiplexes frame mode data in an AAL2 connection. It fragments very large amount of data of a frame and packed in an
AAL2 connection thus can assure assigned QOS for the service.
- UNI
GL's ATM analyzer can be configured to support following UNI interfaces:
- ITU-T Standard Interfaces(UNIQ.2931) :
Q.2931 based UNI signaling is an ITU-T UNI signaling standard used to
establish and release of SVC. SVC is switched virtual channel created using signaling protocol when it is needed and then
later on released. Various variants of UNI signaling are available.
- ATM Forum Standard Interfaces (UNI 3.0, UNI 3.1, UNI 4.0):
Similar to Q.2931, ATM forum has defined it's own
recommendations for establishment and release of SVC across ATM User-Network interface. The procedures described in
these recommendations apply to both public UNI as well as private UNI.
Summary, Detail, and Hex-dump Views
The ATM analyzer application is invoked from the main menu of GL's T1/E1 Analyzer for real-time analyzer. The offline ATM
analyzer is invoked from the installation directory of the offline ATM Analyzer. The analyzer displays summary, detail, call trace,
statistics, and hex dump views in different panes. The summary pane displays Dev#, Time Slot, Frame#, Time, Length, Error,
VPI/VCI, PT and so on. User can select a frame in summary view to analyze and decode each frame in the detail view. The Hex
dump view displays the frame information in HEX and ASCII format.
Screen Shot of Summary, Detail and Hex-dump Views
Real-time and Offline Analysis
Users can capture and analyze UNI and NNI interfaces in real-time and record all or filtered traffic into a trace file. The
recorded trace file can then be analyzed offline and exported to ASCII file, or printed. User can capture raw ATM data and
can then transmit using playback file application.
Recorded trace file can be opened later for offline analysis. ATM raw data capturing requires user to specify timeslots, bit
inversion, octet bit reversion, user/network side, ATM mapping, scrambling, and inverse multiplexing options. Captured data
can then be transmitted using playback file application.
Screen Shot of Timeslot selection
Inverse Multiplexing in ATM (IMA)
The ATM Analyzer is enhanced to capture & reassemble frames that were transmitted with Inverse Multiplexing option.
With Inverse Multiplexing in ATM (IMA) feature, up to 8 T1/E1 links can be configured to form a high-speed connection. ATM
cells are transmitted across multiple interfaces in a cyclical fashion, and recombined to form the original stream.
Screen Shot of IMA Working Principle
Screen Shot of Captured ATM frames with IMA
Filtering and Search
Users can record all or filtered traffic into a trace file. Filtering and search capability adds a powerful dimension to the
ATM Analyzer. This feature can isolate required frames from all the captured frames in real-time, as well as offline. Users can
specify custom VPI, VCI, and PT type values to filter frames during real-time capture. The frames can also be filtered after
completion of capture according to Dev#, Time Slot, Frame #, Time, Length, Error, VPI/VCI, PT (Payload Type), HEC, OSF,
AAL Type, Frame Type, CID, LI, CPI, UUI, and more. Similarly, search capability helps user to search for a particular frame
based on specific search criteria.
Screen Shot of Setting the Filtering Criteria
Screen Shot of Setting Real-time Capture Filter
Reassembly
Using reassembly option user can specify VPI /VCI value to reassemble as per the Segmentation and Reassembly rules
defined by the specified AAL type. It multiplexes ATM cells as per the user specified VPI/VCI/AAL type into CPS or SAR frames.
ATM cells not satisfying the user specification will be reassembled as per the default specification.
Screen Shot of Reassembly Parameters
Call Trace & Statistics View
Call trace defining important call specific parameters like Call ID, Call disposition, Call duration, VPI/VCI, Call type
(point-to-point/point-to-multipoint etc) calculated based on UNI signaling messages are displayed in Call Trace view.
Statistics is an important feature available in ATM analyzer and can be obtained for all frames both in real-time as well as
offline mode. Various statistics can be obtained in statistics view to study the performance and trend in the ATM network based
on different parameters e.g. Use Type, Statistic type and various patterns.
Screen Shot of Statistics Window
Enhanced Trace Saving Options
Users can control the captured trace files by saving the trace using different conventions such as trace files with
user-defined prefixes, trace file with date-time prefixes, and slider control to indicate the total number of files, file size,
frame count, or time limit. This feature also allows the captured frames to be saved into a trace file based on the filtering
criteria set using display filter feature.
Screen Shot of Enhanced Trace Saving Options Window
Save/Load All Configuration Settings
Protocol Configuration window provides a consolidated interface for all the important settings required in the analyzer.
This includes various options such as protocol selection, startup options, stream/interface selection, filter/search criteria and
so on. All the configuration settings done can be saved to a file and then loaded from a configuration file. Users may also just
revert to the default settings using the default option.
Screen Shot of Save/Load All Configuration Settings Window
Bridge and Monitor Connections
Buyer's Guide:
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 HDT, HDE, HUT, HUE, UTA or UEA depending
upon the hardware.
* Specifications and features subject to change without notice.
Back to Protocol Analysis Index Page
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