GL Announces ExpertTCP™ to Ethernet/IP Test platform

Welcome to December 2016 issue of GL's Newsletter providing information and insight into our enhanced PacketExpert™ - a Quad Port Ethernet/IP Tester.  It is enhanced to support RFC 6349 frame work for TCP Throughput Testing Methodology referred to as ExpertTCP™.

ExpertTCP™ Test Setup

ExpertTCP™ Test Setup

Why we need ExpertTCP™?

IP Network operators and Service providers need to verify that their networks are performing well and meet the Service Level Agreements (SLA) with the customers.  To verify Ethernet/IP based networks, current widely used standards are RFC 2544 or Y.1564. However, both these standards are meant for testing at Layer2 or Layer3 (Ethernet or IP layers). Though these tests are necessary, they are not sufficient, because they do not cover testing at TCP layer. Most web based applications like Http, FTP, E-mail etc. run over TCP. Even many modern web applications like Facebook, YouTube and the like use TCP.  Even if service provider networks are tested using RFC 2544 or Y.1564, customers may still face problems with TCP throughput.

Testing TCP layer

The TCP throughput may not match the throughput at the Ethernet/IP layer. This is because TCP throughput depends on factors like the end node TCP Window Size, buffer size of intermediate network nodes etc. Also, impairments like latency and packet drops causes TCP retransmissions, severely affecting the TCP throughput. So, there is a gap in the current testing methods and to cover the gap RFC 6349 frame work has been devised.


GL's PacketExpert™, both PacketExpert™ 1G and PacketExpert™ 10G  have been enhanced to support RFC 6349 based TCP Throughput (ExpertTCP™) test functionality.

PacketExpert™ 1G has four 10/100/1000 Mbps Electrical/Optical ports and PacketExpert™ 10G has two 10 Gbps Optical ports and two 10/100/1000 Mbps Electrical/Optical ports and both are capable of Bit Error Rate Testing (BERT), Smart LoopbackRFC 2544 Testing,  Record and Playback, Single Stream and Multistream Simulation of IP Links and Impairments (IPLinkSim™ and IPNetSim™), Multi-Stream Traffic Generation and AnalysisPacketBroker™, and Y.1564 Testing (ExpertSAM™).

Functional Procedure

ExpertTCP™ performs bidirectional TCP throughput measurements in combination with another unit at the remote location (other end of the network), that acts as the TCP server, as depicted in the main diagram titled ExpertTCP™ Test Setup.

Many real-world networks are not symmetrical. There may be significant differences between upstream and downstream directions. ExpertTCP™ supports both Upstream (Client → Server) and Downstream (Server → Client) direction testing. Bidirectional simultaneous testing/unidirectional testing can be done. Results are reported for both directions.

The server located at the remote location is completely controlled by the client side (located locally). User enters the entire configuration (both client and server configuration) locally, and results are displayed locally, avoiding the hassles of configuring the test at multiple locations.

Important Features

  • Path MTU, Baseline RTT and TCP Throughput tests supported for both directions (upstream and downstream) independently
  • Supports Upstream (Local to Remote), Downstream (Remote to Local) and Bidirectional tests
  • Hardware FPGA based TCP implementation supports full duplex bidirectional wirespeed TCP (up to 1 Gbps in both directions simultaneously)
  • Supports multiple TCP connections (up to 16 TCP connections)
  • Test asymmetrical path with separate set of configurations for Upstream and Downstream
  • Complete remote control -  user needs to interact only with local side - all results/statistics (both local and remote side) provided on local side
  • Detailed run time statistics with graphs for easy visualizations
  • RFC 6349 specified metrics - TCP Efficiency, Buffer Delay Percentage, TCP Transfer Time ratio
  • Command Line Interface for automated testing and remote accessibility

Statistics and Results

Detailed runtime statistics are available

Throughput results
RTT results

Graphs provide easy visualizations to troubleshoot problems. Final results include the RFC6349 specified TCP metrics, as well as comparision of actual with the Ideal values.

TCP metrics 1g
Throughput vs retransmitted graph

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