IPv4 Header vs IPv6 Header Explained

IPv4 Header fields are discussed and compared with IPv6 Header fields in this video.
Version 4 bits field used to indicate the version of IP (filed available in both IPv4 and IPv6).
Length- (IPv4) 4 bits field used to indicate the header length, it has been removed from IPv6 header.
DS- Differentiated Service /Type of service field (IPv4) 8 bits field replaced by Class field in IPv6 packet.
Traffic Class 8 bits field indicating class or priority of IPv6 packet (delay, throughput, reliability)
Packet Length (IPv4) – 16 bits field Indicating the total packet length is replaced by Payload length field.
Payload Length – 16 bits field Indicating the length of the IPv6 payload. It includes the Extension Headers and PDU from upper layer (Max payload = 2^16). For larger payload , Extension header needs to be used.
Flow label 20 bits field used to Indicate that the current packet belongs to some specific sequence of packets, with specific priorities, travelling between source and a destination and require special handling by routers
Identification, Flags, Fragment Offset, Header Checksum (IPv4)– These fields are removed in IPv6. Fragmentation, Options information is placed in Extension Headers, checking is done at link layer
Time to Live (IPv4)- 8 bits field has been replaced by Hop Limit field.
Hop Limit- 8 bits field indicating the life of a packet in terms of number of hops.
Protocol (IPv4)- It given information about upper layer protocol.
Next Header – 8 bits field mostly similar to Protocol field in IPv4 indicating upper layer protocols like UDP, TCP, ICMPv6 messages.
Source Address (32bits IPv4) 128 bits field indicating the address of the source
Destination Address (32bits IPv4) 128 bits field indicating mostly the address of the destination
Options (IPv4)- Functionality of options is moved to Extension headers

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