In general, to perform a loopback test requires two test ports on both packet generator and DUT/NUT for transmission and receiving of test packets. It may not be available to do the loopback test in real network environment if the network under test is located far away from the packet generator with only one linked network cable.
Utilize one network cable to fulfill the loopback test is the best way in real network environment. To achieve the goal, loopback device LB-100 is just suitable for this test. LB-100 filters broadcast, multicast packets and resends the rest of test packets to the same network cable by two selective methods; resends directly (layer 1 loopback) or resends with swapped DA/SA (destination / source MAC address) and recalculated CRC for different applications (layer 2 loopback).
Packet generator such as NuDOG of Xtramus can generate and receive Throughput, Latency or Loopback test patterns for analysis via one network cable. For this application, the loopback device, LB-100 is connected at remote location to resend the loopback or others test patterns. By this way, extra network cable is not required for the test.
Easy and distinctive real-time LED indicators for network speed, duplex mode, loopback mode, packet length, common errors, utilization and elapsed test time in LED digits display make LB-100 not just a loopback device, but also a full functional link tester.
LB-100 Block Diagram
Layer 1 or 2 Loopback Test by NuDOG and LB-100
Feature
Two selective Loopback modes. Layer 1 loopback and Layer 2 loopback for two individual port.
Perform round-trip Throughput and Latency test by NuDOG with NuDOG-2544 application software.
Handheld device that is portable to any test site.
Elapsed Time shown on LED digits display in order to know the duration of a single test.
Two network ports for 2 sets of individual loopback test simultaneously. Convenient hotkey to switch the loopback mode for different port (A or B) in the test.
Distinctive LED indicator that is able to pinpoint the status of current running network.
Clear the status LED by hotkey any time for next loopback test. Status is kept unless clear hotkey is pressed.
Real-time LED indicator of network speed, duplex mode, loopback mode, packet length, common errors (CRC, Loss), utilization and elapsed test time in LED digits display.
Support throughput and latency test of round-trip (loopback) network in one device
Compact and portable size that is easy to carry for on-site test.
Replaceable battery pack for the technical personnel to perform loopback test all day long.
Charge external battery pack by convenient USB port
Check before acceptance of network wiring task that is done by third party contractor
Do loopback test by one linked route in real network environment that is much better then two routes loopback.
Variety of test features when it works with test equipment (NuDOG) and software utility of Xtramus.
As a link tester that is able to detect the link speed, duplex mode if loopback mode is not activated.
View network utilization in Mbps by 6 LED indicators.
Collaborate with other brand packet generator/analizer for loopback test.
Interface
Front Side:
2 x UTP network port for JR-45 connector
Rear Side
Mini-USB port to acquire power from power adaptor or USB port of PC
LED Indicator
Power: Power status
Status of port A
ON: ON for loopback mode and blinking indicates loopback packets is forwarding
Link: Network cable is linked up.
100M: 100Mbps connection
10M: 10Mbps connection
Full: Full duplex mode
Tx: Packets is transmitting
Rx: Packets is receiving
Loopback1: Layer 1 loopback mode
Loopback2: Layer 2 loopback mode (default)
Status of port B
Same LED indicators as above for port B
Rx packet length and error of Port A
64: Received frame (packet) is equal or beyond 64 bytes and below 127 bytes
128: Equal or beyond 128 and below 255 bytes
256: Equal or beyond 256 and below 511 bytes
512: Equal or beyond 512 and below 1023 bytes
1024: Equal or beyond 1024 and below or equal 1517 bytes
Long: Equal or beyond 1518 bytes
Note: LB-100 subtracts 4 bytes for VLAN tagged frame
CRC: CRC error found
Lost: Packet loss found
Note: LED of all receiving status keep ON if the case happens, unless Clear key is pressed.
Rx packet length and error of Port B
Same LED indicators as above for port B
Receiving Rate: Indicate utilization by Blinking for port A or ON for port B
Utilization: Show A or B traffic rate according to Receiving Rate LED above
4Mbps, 8Mbps, 16Mbps, 80Mbps, 90Mbps, 100Mbps
Note: LED indicator is ON all the time if the case happens. 100% is wirespeed. When real rate is approaching marked LED, the LED is blinking
Speed and Mode
Auto Negotiation (for port A and B)
10/100Mbps Half / Full Duplex
Auto MDI/MDIX
Support
Loopback
Layer 1 and layer 2 loopback
Applications
Work with packet generator such as NuGOG of Xtramus for loopback test
Perform network Throughput and Latency test by NuDOG with NuDOG-2544 software application tool.
Detect network link status for troubleshooting / debugging purpose after wiring of network cable.
Monitor network utilization by real-time LED indicator
Transmit Mode
Loopback mode: As a loopback client that returns incoming test streams for loopback (round trip) test.
Layer 1 loopback that filters out broadcast, multicast and null DA packets and resend the rest of incoming packets directly.
In addition to layer 1 loopback function, layer 2 loopback also resend packets with switched DA / SA (destination / source MAC address) and recalculated CRC for different applications.
Miscellaneous
Operation Hotkey
On / Stop: Start/Stop to forward packets for the loopback test
Config A/B: Circulated configurations around ports and loopback modes
Clear A/B: Clear LED indicator of port A and port B for next loopback test
Rate Display A/B: Switch Receiving Rate LED between port A and port B. LB-100 can display A or B once a time.
External Battery Pack
Able to mount external battery pack to LB-100 for on-site test without power supply.
USB port of both LB-100 and battery pack are all for power supply or charge purpose without data link to PC
Feature
