datagram in IPv6 consists of Base Header, Optional Extension Headers, and the Data Area. The Base Header is twice as large than in IPv4 due to the added extra 96 bits to the each destination and source addresses, but it actually contains less data. It contains: VERS – for version IPv6, PRIORITY – specifies the urgency0 Uncharacterized traffic 1 "Filler" traffic (e.g., Netnews) 2 Unattended data transfer (e.g., email) 3 (Reserved) 4 Attended bulk transfer (e.g., FTP, HTTP, NFS) 5 (Reserved) 6 Interactive traffic (e.g., telnet, X) 7 Internet control traffic (e.g., routing protocols, SNMP), FLOW LABEL – designed for use with performance dependant applications, PAYLOAD LENGTH –how much data is in the packet, NEXT HEADER – tells what is the data going to be in the next header, HOP LIMIT – same as time to live, and SOURCE and DESTINATION addresses. The Base Header takes 40 octets without the optional headers. The IPv6 also differs in the way it is assigning addresses. It has 3 different types: unicast, multicast and anycast. UNICAST (uni – one) address corresponds to the single machine and datagram is given a shortest possible path. MULTICAST corresponds to the set of nodes is dynamic they can change over time. ANYCAST sends one copy of a datagram to the group of PCs that share same class prefix (same network). IPv6 alsosaves space by using ‘0’ address compression which works by compressing many 0’s in one row into smaller equivalent.The other advantage of IPv6 over IPv4 is the better data security. This is achieved by adding two optional extensions “Authentication Header” provide authentication and integrity to IPv6 datagrams. The second security extension header provided with IPng is the "IPng Encapsulating Security Header" this mechanism provides integrity and confidentiality to IPv6 datagrams. Both extension headers are flexible and algorithm i...
