AUI trasceiver

Force AUI transceiver in both cards.

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.

IP

• Set interface eth0 to IP address 192.168.1.1 and netmask 255.255.255.0 (Linux: ifconfig eth0 192.168.1.1 netmask 255.255.255.0).
• Set up eth1 to IP address 192.168.2.2 and netmask 255.255.255.0 (Linux: ifconfig eth1 192.168.2.2 netmask 255.255.255.0) Get and write down on a piece of paper the MAC address of eth1 (Linux: ifconfig eth1).

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

Ping

• Take another console or open new terminal window.
• Start sending periodical ICMP Echo Request packets to IP address 192.168.1.2 with 1-second intervals (Linux: ping 192.168.1.2)
• The sniffer (Linux: tcpdump or Wireshark for example) should show ICMP Echo Requests. If not, test has failed.

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.