Overview
The Multi-Class Extension to Multi-Link PPP allows a sender to fragment the packets of various priorities into multiple classes
of fragments, and allows high-priority packets to be sent between fragments of lower priorities.
MLPPP bundles multiple link-layer channels into a single network-layer channel. Data sent through this channel will be
distributed among all the links.
GL's flexible and versatile MC-MLPPP Emulator is GUI based WCS client, which simulates MC-MLPPP and PPP protocols
over T1/E1 links. The unit is capable of generating and receiving MC-MLPPP/PPP traffic (with or without impairments). Traffic
source can be sequence number, HDL files (containing packets/frames), flat binary file, user-defined frames (ASCII HEX file), and
Ethernet data.
MLPPP emulator can be configured as a router or as a bridge to establish connection and route traffic between LANs.
Main Features:
- Performs MC-MLPPP as well as PPP simulation
- Supports LCP with the following negotiation options
- PPP options: MRU (Maximum Receive Unit), ACFC (Address and Control Field
Compression), PFC (Protocol Field Compression), and Magic Number
- MLPPP Options: MRRU (Maximum Received Reconstructed Unit), Short Sequence
Number Format, and Endpoint Discrimination
- Multi-Class Options: Multilink Header Format
- Supports the following NCP
- IPCP in RFC 1332 (The PPP Internet Protocol Control Protocol) and RFC 1877 (PPP Internet
Protocol Control Protocol Extensions for Name Server Addresses) standards
- BCP in RFC 3518 (Point-to-Point (PPP) Bridging Control Protocol) standard
- Payload traffic generation and verification using Sequence number, HDL file (containing packets/frames),
Flat Binary file, Ethernet traffic, and User defined frames (ASCII HEX file) for each class independently
- Transmit and receive Ethernet traffic over T1E1 links by operating either in bridge or router mode
- Supports up to 8 T1/E1 links
- Differential link delay insertion between PPP links during transmission
- User configurable timers and counters like Restart-timer, Max-Configure, Max-Terminate, and Max-Failure
- User configurable bandwidth using flags
- Supports hyper channels with discontinuous (sparse) timeslots
- Supports full or fractional timeslots for PPP Link
- Supports Fragmentation and Reassembly at MLPPP level
- Dynamically add/remove (open/close) PPP links without loss in data
- Supports various impairments at PPP layer - CRC error, frame error, frame duplication, and more
- Supports various Fragment/Packet impairments for each Class at MLPPP level
- Provides detailed PPP and MLPPP statistics
- Provides detailed test (Tx/Rx) results per class / per link in GUI as well as through log file in command line
- Ideal solution for automated testing using command line scripts
- Support for HDLC framing with CRC16, CRC32 or without CRC
References
- RFC 1661 Point-to-Point Protocol (PPP)
- RFC 1662 PPP links in HDLC framing
- RFC 1990 Multi-link PPP bundles
- RFC 2686 Multi-class extensions to PPP
- RFC 1332 The PPP Internet Protocol Control Protocol
- RFC 1877 PPP Internet Protocol Control Protocol Extensions for Name Server Addresses
- RFC 3518 PPP Bridging Control Protocol
Screen Shot of GUI Based MC-MLPPP Emulator
Screen Shot of Command Line Based MC-MLPPP Emulator
PPP Configuration and Adding Links
Various PPP links (of any bandwidth varying from 64Kbps to n*64Kpbs or sub channels) can be added to form the MLPPP bundle.
Each of the added links in the bundle can be configured with selected PPP, MLPPP, and Multi-class configuration options. PPP
options can be selected for each link individually, however, MC and MLPPP options are selected for the complete bundle.
The PPP configuration parameters include Max-Configure, Restart-timer, Max-Terminate and Max-Failure. The HDLC configuration
allows configuring the CRC parameters for HDLC frames.
As the transmission and reception is in progress, any of the PPP links in the bundle can be removed (terminated) or
added back to the bundle without loss in data. All the actions performed in GUI can also be executed through command
line interface.
Click
here to download a sample script that illustrates addition and removal of PPP links
Screen Shot of PPP and HDLC Link Configuration
Screen Shot of adding PPP links
Link Control Protocol Negotiation
MC-MLPPP supports Link Control Protocol (LCP) to configure PPP links with the various negotiation options. Link
configuration is an optional feature and is enabled by default.
If LCP is enabled for a link, then opening that link performs Link Configuration (negotiation) by exchanging LCP
Configuration packets with peer end. If LCP is disabled, then link configuration is disabled and on opening, the link
will go to UP state assuming that the peer end is also up.
Screen Shot of LCP Negotiation at PPP Level
Screen Shot of LCP Negotiation at MLPPP Level
Network Control Protocol Negotiation
The application supports NCP negotiation option over MLPPP or PPP. The NCP configuration option allows negotiation of
IPCP or BCP protocols. In MLPPP Simulation, NCP negotiation starts as soon as any PPP link in the bundle is negotiated for
LCP parameters.
- RFC 1332 - The PPP Internet Protocol Control Protocol
- RFC 1877 - PPP Internet Protocol Control Protocol (IPCP) Extensions for Name Server Addresses
- RFC 3518 – Point-to-Point (PPP) Bridging Control Protocol (BCP)
For NCP over PPP, the NCP packets will be sent over PPP links directly rather than over MLPPP. For NCP over MLPPP, the
NCP packets will be sent over MLPPP bundle.
Screen Shot of IPCP and BCP Negotiation
Link Test using Echo Request/Reply
Link Testing is used for testing link connectivity. When the link status is UP,it will test by sending LCP keep alive messages
(Echo Req/Reply). The Link Test provides test parameters along with the statistics of number of requests sent and number of replies
received.
Screen Shot of PPP Link Test
Traffic Generation and Verification
In MLPPP Simulation the traffic is generated and received on the entire MLPPP bundle for various classes. But in PPP
simulation, PPP traffic can be generated and received on each PPP link individually. Tx parameters are used to generate
traffic and Rx parameters are used as reference to verify the received frames.
GUI provides options to add classes to MLPPP bundle or PPP links for Tx/Rx traffic. All the actions performed in GUI
can also be executed through command line interface.
Click
here to download a sample script that illustrates the transmission and reception of traffic in mlppp and ppp simulation using Sequence numbers.
Click
here to download a sample script that illustrates the transmission and reception of traffic in mlppp and ppp simulation using HDL Trace Files.
The MC-MLPPP 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 MLPPP Analyzer.
- Network traffic (LAN traffic) - This allows user to receive traffic from Ethernet, convert to PPP traffic and send through
T1/E1 line and vice versa. MLPPP emulator can be configured in router mode or 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.
Screen Shot of Data Transmission and Reception over MLPPP
Screen Shot of Data Transmission and Reception over PPP
Screen Shot of Data Transmission and Reception over Network Traffic
- MLPPP Emulator as a Router
Subnet1 and Subnet2 have been connected through T1/E1 lines using MLPPP Emulator that is configured to work as router.
The 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 MLPPP links. Emulator respond to all ARP requests whose IP
addresses present in routing table.
The Emulator allows user to configure which MLPPP class can be used based on the parameters set in Priority Dialog table -
Packet Length, Source IP Address, Destination IP Address, and IP Type of Service (TOS).
- MLPPP Emulator as MLPPP Bridge
When the emulator is configured to act as bridge between two networks, all ARP and traffic (checked against the priority
table) received from the network is encapsulated as BPDU (Bridging Protocol Data Unit) and streamed over T1/E1 links.
The Emulator on another network removes BPDU header, converts to Ethernet and streams to the destination.
Impairments
Various impairments can be introduced before frames are transmitted or during traffic generation. In PPP simulation
frames are impaired by applying impairment to a particualar ppp link . In MLPPP Simulation frames can be impaired by
applying impairment at fragment lever, packet level or any of the PPP links in the bundle. Flexible support for impairments
during test allows various protocol and payload errors insertion. One can specify a limited number of impairments or
continuous impairment.
Impairments can affect an entire PPP frame and can belong to the following types:
- CRC Error
- Frame Error
- Frame duplication
Impairments can also modify some octets in a frame at a certain offset and can include:
- Inserting octets
- Deleting octets
- Bitwise ANDing octets
- Bitwise Oring octets
- Bitwise XORing octets
Differential delay can be introduced between PPP links
Screen Shot of Impairments at PPP layer
Screen Shot of Impairments at MLPPP layer
Click here
to download a sample script that illustrates impairment of a PPP and MLPPP link during transmission of traffic.
Data Verification using Statistics
MLPPP Statistics:
MLPPP statistics provides important information about the MLPPP bundle such as Number of transmitted/received octets,
frames, fragments, lost fragments, and PPP/ML/MC packet fragments received with invalid sequence numbers.
Screen Shot of MLPPP Statistics
Tx/Rx Verification
Traffic verification results provides the overall statistics for all classes (MLPPP Simulation) or links (PPP Simulation). The
statistics include number of Transmitted, Received, Matched, Modified, Inserted and Deleted frames.
Screen Shot of Tx/Rx Verification in PPP Simulation
Screen Shot of Tx/Rx Verification in MLPPP Simulation
PPP and HDLC Statistics
PPP Statistics provides important statistics information for the selected PPP link, such as the Number of transmitted/received
octets, frames, PPP packets with bad addresses, PPP packets with bad control bytes, and PPP packets exceeding the MRU. The
errors that occur during file transmission like the Tx Under/Over Runs, Rx Under/Over Runs, Number of PPP packets with bad FCS
and Number of Frame Errors are recorded in the HDLC Statistics.
Screen Shot of PPP Statistics
Screen Shot of HDLC Statistics
Detail Log File
This option is available in command line only. The optional log file produced by
the WCS task shows the hex data dump to understand the source of errors along with the timestamp. This can be useful to
diagnose problems.
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 DPT, DPE, PCT, PCE, HDT, HDE, DLT, DLE or UTE depending upon
the hardware.
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