Ip Address Scheme
IP Address scheme:
IPv4 operates on 32-bit addresses.
32 bit address = Byte 1| Byte 2| Byte 3| Byte 4
Class Prefix Network Number Host Number A 0 0-7 8-31 bits B 10 1-15 16-31 bits C 110 2-24 25-31 bits D 1110 Multicast E 1111 N/A
The bits are ordered from left to right. The first bit is the leftmost bit, the last bit is the rightmost bit.
For each class of network, we observe
Class Range of Net numbers Range of host numbers
A 0 to 126 0.0.1 to 255.255.254 B 128.0 to 191.255 0.1 to 255.254 C 192.0 to 254.255.255 1 to 254
Any address starting with a 127 is a loop-back address and only used for addressing the host.
All binary 1s at the host number means a broadcast to all hosts on that network.
Ex. 198.60.81.255 is a broadcast over 198.60.81 network.
If all binary 0s at the host number, it means “this host”.
If all binary 0s at the network address, it means “this net”.
Basic IP addressing and ARP
[pic]
Host 1 wants to send a message to 2 on the same network. Host knows its IP address, but doesn’t know its MAC address. ARP (Address Resolution Protocol) is used for dynamic discovery of MAC addresses.
ARP keeps an internal table like
|IP-address |MAC address |
| … |… |
| … |… |
| | |
| | |
| | |
ARP Table:
If Host-1 doesn’t have Host-2’s entry, ARP-module will find that Host-2’s
IPv4 operates on 32-bit addresses.
32 bit address = Byte 1| Byte 2| Byte 3| Byte 4
Class Prefix Network Number Host Number A 0 0-7 8-31 bits B 10 1-15 16-31 bits C 110 2-24 25-31 bits D 1110 Multicast E 1111 N/A
The bits are ordered from left to right. The first bit is the leftmost bit, the last bit is the rightmost bit.
For each class of network, we observe
Class Range of Net numbers Range of host numbers
A 0 to 126 0.0.1 to 255.255.254 B 128.0 to 191.255 0.1 to 255.254 C 192.0 to 254.255.255 1 to 254
Any address starting with a 127 is a loop-back address and only used for addressing the host.
All binary 1s at the host number means a broadcast to all hosts on that network.
Ex. 198.60.81.255 is a broadcast over 198.60.81 network.
If all binary 0s at the host number, it means “this host”.
If all binary 0s at the network address, it means “this net”.
Basic IP addressing and ARP
[pic]
Host 1 wants to send a message to 2 on the same network. Host knows its IP address, but doesn’t know its MAC address. ARP (Address Resolution Protocol) is used for dynamic discovery of MAC addresses.
ARP keeps an internal table like
|IP-address |MAC address |
| … |… |
| … |… |
| | |
| | |
| | |
ARP Table:
If Host-1 doesn’t have Host-2’s entry, ARP-module will find that Host-2’s