IPv4 Header Part All Field’s Description-
Today we are going to talk about Ipv4 header part. In order to understand you must need to know what is IP and what are versions of IP i.e. ipv4 and ipv6.
Header part of IPv4 contains the two parts-
1) Fixed part (20 Bytes long)
2) Variable part ( Variable length)
IPv4 header part contains the 13 fields-
1)Version- It is the very first field of the ipv4 header format. It tells about that which version of IP we are using. All information related to the version of IP is stored in this field. In case of IPv4 the value is 4.
2)IHL-IHL stands for the Internet header length. It is generally between 20 Bytes to 60 Bytes. It provide the information about length of header to the network.
3)TOS-TOS is stands for Type of Service. What type of services providing by the header. E.g. Reliability, Speed, Throughput and delay etc. and it is rarely used. It is 1 byte field.
4)Total length- Total length tells us the total length of Header part + Data. We can get length of data by subtracting header length from the total length as we have a separate field for header length i.e. IHL.
5)Identification- It is 16 bit field which helps to destination host to identify the datagram of currently received fragment.
6)Flags-It is a 3 bit field in which 1 bit is unused, and other two field are DF and MF. DF stands for Do not fragment and MF stands for More fragment. DF is generally an instruction to router to do not fragment data and MF is used when all fragment of datagrams are received.
7)Fragment Offset- It is a 13 bit field which gives information about the position of current fragment in the datagram.
8)Time to Live- 8 bits field and allows a datagram to a particular time in which they can remain on the internet and after specified time is over than it is discarded. Minimum 0 seconds to Maximum 255 seconds.
9)Protocols- It is 8 bits long and tells which protocols we are using. It may be ICMp,IGMP,TCP,UDP or OSPF.
10)Header Checksum- It if of 16 bit field which checks the header part and verify it. And also it checks for the errors in the header part.
11)Source address- Source address is of 30 bits and tells about the information of source Or sender like Class Type, IP address, Network ID number.
12)Destination address- Simply tells about the Destination address i.e. IP of destination address.
13)Optional Field-It may contains the other information like Security or Routing which may help in to reduce error and testing of network.
Visit here Click Here for IPV6 header format