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The first header field in an IP packet is the Version field. For IPv4, this is always equal to 4. Internet Header Length (IHL): 4 bits The IPv4 header is variable in size due to the optional 14th field (Options). The IHL field contains the size of the IPv4 header; it has 4 bits that specify the number of 32-bit words in the header.
This is a list of the IP protocol numbers found in the field Protocol of the IPv4 header and the Next Header field of the IPv6 header. It is an identifier for the encapsulated protocol and determines the layout of the data that immediately follows the header. Both fields are eight bits wide.
The principal packet structure of ARP packets is shown in the following table which illustrates the case of IPv4 networks running on Ethernet. In this scenario, the packet has 48-bit fields for the sender hardware address (SHA) and target hardware address (THA), and 32-bit fields for the corresponding sender and target protocol addresses (SPA ...
Internet Protocol version 4 (IPv4) was the first standalone specification for the IP address, and has been in use since 1983. [2] IPv4 addresses are defined as a 32-bit number, which became too small to provide enough addresses as the internet grew, leading to IPv4 address exhaustion over the 2010s.
For these purposes, the Internet Protocol defines the format of packets and provides an addressing system. Each datagram has two components: a header and a payload . The IP header includes a source IP address, a destination IP address, and other metadata needed to route and deliver the datagram.
The Internet checksum, [1] [2] also called the IPv4 header checksum is a checksum used in version 4 of the Internet Protocol (IPv4) to detect corruption in the header of IPv4 packets. It is carried in the IPv4 packet header, and represents the 16-bit result of the summation of the header words. [3] The IPv6 protocol does not use header checksums.
Time to live is a field that is decreased by one each time a packet goes through a network hop. If the field reaches zero, routing has failed, and the packet is discarded. [6] Ethernet packets have no time-to-live field and so are subject to broadcast storms in the presence of a switching loop. Length
When extension headers are present in the packet this field indicates which extension header follows. The values are shared with those used for the IPv4 protocol field, as both fields have the same function (see List of IP protocol numbers). Hop Limit: 8 bits Replaces the time to live field in IPv4. This value is decremented by one at each ...