IP Network Layer and Ethernet Encapsulation

1
IP Network Layer and Ethernet Encapsulation

• Lab exercises

2
IP addresses

• Host IP address
• 130.65.241._____
• Network address
• 130.65.241.0
• Netmask
• 255.255.255.128
• Broadcast address
• 130.65.241.127

3
Class diagram
130.65.241.0/25
130.65.241.0/25
.42
.41
eth0
eth0
.1
.2
eth0
eth0
130.65.241.48/25
130.65.241.56/25
130.65.241.8/29
130.65.241.0/25
.50
.49
.58
.57
.17
eth0
eth0
eth0
eth0
.10
.9
.18
eth0
eth0
eth0
eth0
.135
eth1
130.65.241.64/25
130.65.241.72/25
130.65.241.0/25
130.65.241.24/25
.65
.66
.73
.74
.25
.26
.33
.34
eth0
eth0
eth0
eth0
eth0
eth0
eth0
eth0
130.65.241.0/25
4
Ping - Exercise 1

• Step 1
• Load Ethernet Driver
• modprobe eepro100
• Check
• lsmod
• see if module loaded

5
Ping - Exercise 1 (cont.)

• Step 2
• Configure interface
• ifconfig eth0 ltIP addressgt netmask ltnetmaskgt
  broadcast ltbroadcastgt
• For Linux lt 2.2
• route add -net ltnetworkgt netmask ltnetmaskgt
• Check
• ifconfig - check interface
• netstat -nr - check route to network

6
Ping - Exercise 1 (cont.)

• Step 3
• Ping
• ping ltremote IP addressgt
• Try
• other machines
• broadcast address
• Step 4
• Monitor traffic
• tcpdump -i eth0 -n

7
Ping - Exercise 2

• Step 1
• Find your own MAC address
• ifconfig
• Step 2
• Ping your neighbor
• ping ltIP addressgt
• Step 3
• Show ARP cache look for their MAC addresses
• arp -n

8
Ping - Exercise 2 (cont.)

• Step 4
• Show traffic including Ethernet header
• tcpdump -i eth0 -n -e
• Step 5
• On other window (e.g. ALTF2)
• Look for ARP frames
• arp -d ltIP addressgt - Flash ARP entry
• ping ltIP addressgt
• Go back to the first window to look for ARP frames