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IPv4 ADDRESSING and PACKET STRUCTURE. IPv4. Internet Protocol addressing version 4 (IPv4) is the basis of Internet. Every connected host has a four octet address expressed in decimal: AAA.BBB.CCC.DDD For example: 66.102.7.104 (Google)
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IPv4 • Internet Protocol addressing version 4 (IPv4) is the basis of Internet. • Every connected host has a four octet address expressed in decimal: AAA.BBB.CCC.DDD For example: 66.102.7.104 (Google) • A host can send a packet to an IP address and it will be delivered to the correct destination.
CLASSFUL ADDRESSING • Under IPv4 addressing scheme (classful addressing), the class of the network may be A, B or C. The class effects how the four number IP address is intrepreted. For all classes, the last byte is limited between: 1 – 254 - 0: reserved for network address - 255: reserved for broadcast address
A B C
CLASS A (large network): the first byte identifies the network and the last 3 bytes represent an address range for hosts on the network. Byte 1: 1 – 126 Byte 2 and 3: 0 – 255 No. of hosts (max): 16,646,144 • CLASS B (medium network): the first two bytes identify the network and the last 2 bytes represent an address for hosts on the network. Byte 1: 128 – 191 Byte 2 and 3: 0 – 255 No. of hosts (max): 65,024 • CLASS C (small network): the first three bytes identify network and the last byte represent an address for hosts on the network. Byte 1: 192 – 223 Byte 2 and 3: 0 – 255 No. of hosts (max): 254 hosts • CLASS D: Byte 1: 224 – 239 • CLASS E: Byte 1: 240 – 255
Broadcast Address: broadcast address is intended to go to every host on the network. (host address bytes are replaced with 255 (all ones) Example: Class B network with a network address of 174.148.0.0 would have a broadcast address of 174.148.255.255
Network Address: is formed by replacing all host bytes with 0. Example: Class B IP address of 174.148.10.5, has network address of 174.148.0.0 • Network Mask (netmask): a host must know if a received packet relates to the network to which the host is a member. Membership of a network is determined using netmask defined on every network host. netmask = all network bits set to 1, all hosts bits set to 0 Example: Class A = 255.0.0.0, Class B = 255.255.0.0
PRIVATE IP ADDRESS(are not used anywhere on public internet, reserved for private LANs)