Internet Header Length – Indicates the number of 4-byte blocks in the IPv4 header. The size of this field is 4 bits. Because an IPv4 header is a minimum of 20 bytes in size, the smallest value of the Internet Header Length (IHL) field is 5. IPv4 options can extend the minimum IPv4 header size in increments of 4 bytes.

Internet Protocol version 4 (IPv4) is the first version of the Internet Protocol (IP) as a standalone specification. It is one of the core protocols of standards-based internetworking methods in the Internet and other packet-switched networks.

This lesson explains the different fields in the IPv4 packet header like the version, header length, type of service, total length, etc.

Jan 15, 2025 · This tutorial explains the IPv4 header in detail. Learn what an IPv4 header is, how many fields an IPv4 header contains, what the meaning of each field is, and what the value is stored in each field.

The IHL field represents the total IPv4 Header Length, in 32-bit words; an IPv4 header can thus be at most 15 words long. The base header takes up five words, so the IPv4 Options can consist of at most ten words.

Nov 16, 2014 · The Internet Header Length (IHL) field is the number of 32-bit words(=4 bytes) in the IPv4 header, including any options. Because this is also a 4-bit field, the IPv4 header is limited to a maximum of fifteen 32-bit words(=60 bytes)

Mar 25, 2019 · An IPv4 header is a minimum of 20 bytes, and there are options that could increase the length up to 60 bytes, but those options are rarely used, and most are blocked in modern networking. The original idea that IPv4 used has proved to be a poor design, and IPv6 was made with a fixed header size for easier and faster processing.

IHL (Internet Header Length): Specifies the length of the IP header in 32-bit words. 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.

Internet Header Length (IHL) This field (4 bit) indicates the length of the IP header and the unit is 4 bytes (32 bits). So, if the value of this field is 5, it means the length of IP header is 20 bytes (= 5 x 4 bytes).

Aug 2, 2022 · IPv4 packet header. Version: The first 4-bit header field informs about the current IP version in use, which, in this case, is IPv4; Internet Header Length (IHL): The IHL has four bits that specify the number of 32-bit words in the header – the minimum header length is 20 data bytes and the minimum value of this field is five