Protocol Emulation

Windows Client Server (WCS)

Client Server based Multi-link Frame Relay (MFR) Emulator

Frame Relay and MFR Emulation is based on client-server architecture. Acts as a Frame Relay (FR)-MFR Data Terminal Equipment (DTE)/Router and generates traffic in compliance with frame relay fragmentation & reassembly models.

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Client Server based Multi-link Frame Relay (MFR) Emulator


Frame Relay (FR) and MFR, is similar to Multi-Link PPP, and both are a form of inverse multiplexing. Users rely on inverse multiplexing when access line capacity does not scale smoothly, i.e. notice the big jumps in bandwidth from 56kbps, 1.544 Mbps, and 45 Mbps. In such cases, intermediate bandwidth must be derived by aggregating a number of smaller access lines into larger ones. MFR is used to derive a larger frame relay pipe by aggregating smaller frame relay pipes. For example, 5 T1 frame relay pipes could be bundled to appear as a single 7.5 Mbps frame relay pipe. Some of the advantages of using MFR are: better bandwidth sizing according to customer traffic requirements and potentially better QOS by minimizing delay.

MFR works by bundling multiple T1 circuits into a multilink bundle and fragmenting the individual frame relay frames into fragments. These fragments are then transported in parallel over the multiple T1 circuits. At the other end, the fragments are reassembled into the original frame relay frames. The protocol includes the use of sequence numbers to allow the fragments to be reassembled correctly and to ensure that the reconstructed frames are sent out in the original order in which they entered the network.

FR and MFR can be emulated and analyzed using GL's client-server based Multi-Link Frame Relay Emulator and Multi-Link Frame Relay Analysis software modules. These are available as optional applications with GL’s T1 E1 Analysis hardware platforms such as tProbe™ T1 E1 Analyzer, Dual T1 E1 PCIe Express Cards, and Quad/Octal T1 E1 Analyzer.

Multi-Link Frame Relay Emulator can be configured as a router or as a bridge to establish connection and route traffic between LANs. The application may be accessed through a GUI or through command line scripts.

Main Features

  • Performs MFR as well as FR simulation on up to 16 T1 E1 lines
  • Adheres to FRF.12 standards
  • Support two simulation modes - FR and MFR
  • FR links can be created on Full or Fractional Timeslots
  • Group FR links to create a MFR bundle
  • Dynamically add/remove (open/close) of Frame Relay links without loss in data
  • Multiple MFR Bundles/FR links can be created with each bundle/link configured with multiple virtual channels for traffic Tx/Rx
  • Generate and verify end to end traffic on each Virtual Channel
  • Transmit and receive Ethernet traffic over T1 E1 links by operating either in bridge or router mode
  • User configurable FR/MFR packet and fragment size, bandwidth using flags, and maximum link differential delay
  • Supports both Interface (UNI and NNI) and End-to-End fragmentation
  • Payload traffic generation and verification using Sequence number, pre-captured HDL files (containing packets/frames), Flat Binary file, and User defined frame (ASCII HEX file) for each Virtual Channel independently
  • Supports various traffic source/sink types namely, Sequence Number, Binary File, Hex String, and pre-captured HDL files
  • Supports various Byte level, Frame level , CRC error, and Frame error impairments at link level
  • Supports various Byte level and Frame level impairments at Fragment/Packet level for each Virtual Channel
  • Provides detailed statistics for each bundle and virtual channels associated with a bundle
  • Provides end to end traffic verification statistics
  • Ideal solution for automated testing using command line scripts

Pattern/File Traffic

The source of the traffic is either a file or a repetitive pattern as defined by the user. This traffic type can be used for end-to-end testing of the link. Since fixed known traffic pattern is generated, the receiver side can be configured to verify the received traffic against the same fixed pattern.

The verification process will provide results such as how many frames are received and out of which how many have been matched successfully with configured pattern, similarly, how many frames modified etc.

BERT test can also be conducted using various pre-defined patterns or a user defined pattern file. The BERT verification provides statistics like: Bit Errors, Sync Loss Count, Sync Status etc.

A virtual channel is created for selected links or bundle to perform traffic actions. In FR simulation the VC will be created on the selected link from the 'Links' dropdown menu. In case of MFR simulation VC will be created on the selected bundle. Multiple Virtual Channels (VC) can be created on the same physical link with same fragmentation format and fragment size.

Tx parameters will generate the FR traffic. Received data is verified with respect to the selected Rx parameters and results of verification are available in Tx/Rx verification tab. The parameters for each VC are independently set. The Tx/Rx parameter includes:

  • Data Type (Sequence No, Packets from HDL or BIN files, HEX string, or Network Traffic). Network traffic allows users to receive traffic from Ethernet LAN, convert to FR traffic and send through T1 E1 line and vice versa. MFR emulator can be configured to work as router or bridge to establish connection between two systems residing in two different LANs.
  • Data Type Parameters
  • Prefix Header
  • Duration Specification
  • Payload length
  • Impairments

FR - VCs on a Selected Link

FR - VCs on a Selected Link

MFR - VCs on a Selected Bundle

MFR - VCs on a Selected Bundle

TxRx Verification

The results of the verification for each of the added VCs are available in Tx/Rx Verification. The statistics include:

  • The number of VCs created
  • The number of frames transmitted successfully
  • The number of frames received successfully
  • If a received frame is verified successfully, then it will be included in "Matched" Frame Count
  • If a received frame does not match, it will be included in the "Modified" Frame Count
  • If the frame is lost then it will be included in "Deleted" Frame Count
  • If extra frames have been received which were not expected then they will be included in Inserted Frame Count

Tx/Rx Verification for Each VC

Tx/Rx Verification for Each VC

MFR Emulator as a Router

The MFR Emulator allows user to setup routing table by configuring IP Address and Mask. Once configured, the emulator forwards the IP packets which match routing criteria over MFR links. The emulator responds to all ARP requests whose IP addresses present in routing table. Shown above, are two networks, Subnet1 and Subnet2, connected through T1 E1 lines using MFR Emulator that is configured to work as router.

MFR Emulator as a Router

MFR Emulator as a Bridge

When the MFR Emulator is configured to act as bridge between two networks, all ARP and traffic received from the network is encapsulated as bridged IP and streamed over T1 E1 links. The Emulator on another network removes bridging header, converts to Ethernet and streams to the destination.

MFR Emulator as a Bridge

PacketCheck Traffic

MFR-IP-PacketCheck traffic option allows IP traffic generation and reception over FR links. Multiple IP traffic streams can be generated and processed over multiple VCs created within the FR links. Each IP traffic streams can be configured to modify the IP packets with desired custom headers to emulate various protocols. MFR-IP-PacketCheck traffic is used to generate and receive IP packet streams to and from a FR router. The FR Router shall be tested for routing the received packets to the proper destination. Using GL's IP tools like PacketCheck™ and PacketExpert™, one can conduct end-to-end testing of the FR link through the FR router.

PacketCheck Traffic

PacketCheck Traffic Configuration

PacketCheck Traffic option allows to create multiple VCs and multiple Routes on the FR links. Each Route will have its own route configuration parameters and an assigned FR link with the defined VC. Packets that pass through the defined criteria of a route, will be encapsulated with the configured Tx prefix header, and transmitted on the assigned FR link and VC. The packets are transmitted with the specified bandwidth (in percentage) for each route.
Route Configuration

Route Configuration

Link Statistics

Provides important statistics information for the selected link such as such as the Number of frames transmitted, Received frames, Octets Transmitted, and Octets Received.

HDLC Statistics Layer
HDLC Statistics Layer

VC Statistics

The statistics for each of the added VCs are available and these include number of Transmitted and received frames, Fragments, Octets, and Lost fragments.

Tx/Rx Statistics for Each VC
Tx/Rx Statistics for Each VC

HDLC Statistics

Errors that occur during transmission / reception like the Tx Under/Over Runs, Rx Under/Over Runs, number of FR packets with bad FCS, and number of packets with Frame Errors is recorded in the HDLC Statistics fields.

Statistic Layer
Statistic Layer

MFR Emulation using Command Line Interface (CLI)

Adding and Activating Frame Relay links (streams)

Syntax: inform task n "TS [HC|SC] 'Link Name'";
Syntax: inform task n "ACTIVATE TS [HC|SC] 'Link Name'";

It is used to add new frame relay links (streams) to the task. In FR simulation the added links are independent of each other, and Virtual Channels will be created on each individual link. In MFR simulation all the added links will constitute one MFR bundle, and Virtual Channels will be created on the bundle but not the constituent bundle links.

The activate command is used to activate /deactivate the individual bundle links in the MFR bundle. Provides an option to dynamically activate/deactivate the links, deactivated links are not be used for Tx/Rx.

MFR Simulation in CLI

MFR Simulation in CLI

Creating/deleting Virtual Channels on the links

FR simulation:

Syntax: inform task n "CREATE VC HC #1:0..23 DLCI x FRAG FORMAT UNI NNI [END TO END] FRAGSIZE n";

MFR simulation:

Syntax: inform task n "CREATE VC DLCI x [y z ...] FRAGSIZE n";

This is used to create or delete virtual channels on the FR links. In case of MFR simulation, virtual channels are created on the MFR bundle.

Traffic Generation and Verification

FR Simulation

Syntax: inform task n "Tx[Rx]: HC #1:0..23 DLCI x CONT [FRAMES n |EOF] FIXLEN 1500 SEQNUM MSB4 [MSB|LSB 8|2|1]";

MFR Simulation:

Syntax: inform task n "Rx:[Tx:] DLCI x CONT FIXLEN 1500 SEQNUM MSB4";

Aggregated Virtual Channel

Syntax: inform task n "Rx [t]: HC #1:0..23 AVC x CONT [FRAMES n|EOF] FIXLEN 1500 SEQNUM MSB4 [MSB|LSB 8|2|1]";

In MFR Simulation the traffic is generated and received on the entire MFR bundle. But in FR simulation, traffic can be generated and received on each individual FR link. Transmission parameters are used to generate traffic and receiving parameters are used as reference to verify the received frames.

Applying Impairments on Frame transmission

Syntax: inform task n "ERROR REP n [CONT] SKIP m #1:0..23 DLCI x OFFS x DEL x";

To download the Multi-link Frame Relay Client-Server T1 E1 scripts.


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), XUT or XUE (Dual PCIe Express) depending upon the hardware.

 Item Description
XX655 Multi-link Frame Relay Emulation w/ Tx/Rx Test (requires XX634)
  Related Software
ETH100/ETH200 PacketCheck™ - Software Ethernet Tester
XX635, XX636 Multi-link Multi-Class PPP Emulator
XX634 Multi-Channel HDLC Emulation and Analysis & File based High Throughput HDLC Record/Playback
XX610 Transmit and Receive File Capability
XX620 Transmit/Detect digits
XX640 File based HDLC Record/Playback
XX641 File based HDLC Remote Record/Playback
XX130 T1 or E1 Real-Time Frame Relay Protocol Analyzer
OLV130 Offline/ Remote Frame Relay Analyzer
XX135 T1 or E1 Real-time MLPPP Protocol Analyzer
XX136 Real-time Packet Data Analysis for MLPPP Protocol Analyzer
  Related Hardware

QuadXpress T1 E1 Main Board (Quad Port– requires additional licenses) 

OctalXpress T1 E1 Main Board plus Daughter Board (Octal Port– requires additional licenses)
PTE001 tProbe™ Dual T1 E1 Laptop Analyzer with Basic Analyzer Software
Dual T1 E1 Express (PCIe) Boards (requires additional licenses)