Ronja Twibright Labs

Half duplex NED estimation for Ronja 10M Metropolis

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NED estimation of Ronja 10M Metropolis device connected to AUI with 2 half duplex cards and Half Duplex Reduction

INFO

Requirements

  • 1 computer
  • 2 AUI network interface cards (NIC)
  • 1 Half Duplex Reduction (HDR)
  • 1 Ronja 10M Metropolis device or 1 AUI Forte

AUI trasceiver

Force AUI transceiver in both cards.

INFO

Naming convention

In the following, we'll call the interfaces eth0 and eth1. They may be named different, especially on different operating system than Linux.

Connecting device

Insert the half duplex reduction (HDR) into network card AUI connectors so that male "T" goes into eth0 and male "R" into eth1. Connect the device to the HDR.

Drawing
Postscript / PDF / EPS / BIG png / SVG (Inkscape)

Device setup

Connect components together this way.

IP

ARP

Set up a permanent ARP table entry on interface eth0, for IP address 192.168.1.2 and MAC address from the paper (Linux: arp -i eth0 -s 192.168.1.2 <MAC address from the paper>)

Routing table

If the kernel hasn't already done it add a routing table entry for IP address 192.168.1.2 to interface eth0 (Linux: route add 192.168.1.2 eth0)

Sniffer

Download and run an ethernet or IP packet sniffer on eth1. The sniffer must set the interface to promiscuous mode ( tcpdump or Wireshark does). Run the sniffer on interface eth1 (Linux: download and install tcpdump or Wireshark , then issue

tcpdump -i eth1
or sniff all traffic with Wireshark on eth1. Leave the sniffer running.

Ping

Estimation

Change distance between RX and TX until the amount of packets that make it through is the same as the amount that doesn't. This is the point of 50% packetloss. The resulting NED is estimated as 1.8 times distance light travels between RX and TX.

An expected information missing here?