IPv4 Header Fields Explained
Background +
2:10 Header fields discussion
IPv4 header fields makes the header part of IP packet. Different fields and their jobs are:
Source IP Address: contains a 32-bit binary representing IP address of sending node
Destination IP Address: contains a 32-bit binary representing IP address of destination node
Version: indicates the version of IP (IPv4 or IPv6)
Length (4-bits): represents the maximum length of header
Packet Length (16-bits): represent the maximum length of packet. Max. packet length = 2^16= 65535
DS (Differentiated Services) Field: this is replacement of Type of Service (TOS) field
It defines different level of service a packet receives in the network
Identification: Sent by the source to help reassemble any fragments
Flags: indicates for instance if a packet is allowed to be fragmented or not and related matters
Fragment Offset: The Fragment Offset, along with the Identification field, is used to identify packets that have been fragmented and reassemble them in the correct order.
DS (Differentiated Services) Field: this is replacement of Type of Service (TOS) field
It defines different level of services a packet receives in the network. Services include, delay throughput, reliability etc.
Identification: Sent by the source to help reassemble any fragments
Time to Live: describes the maximum hops the packet can take before it is considered lost
Protocol: field used to identify the upper-layer protocol—for example, TCP, UDP or ICMP
Header Checksum : Algorithm used by the routers to check the validity of the packet being processed
Options: Used to provide special routing services
Padding: extra bits added to make header multiple of 32 bits
ipv4
