Question

Question 2 a) Draw and compare an IPv4 header and an IPv6 header. Give reasons for the differences between IPv4 and IPv6 headers. [5 Marks] b) Including the Inter-Frame Gap (IFG), calculate the maximum data utilisation of this arrangement with a TCP/IPv4 packet for 100 Mbps Ethernet systems. [5 Marks] c) Including the Inter-Frame Gap (IFG), calculate the maximum data utilisation of this arrangement with a TCP/IPv6 packet for 100 Mbps Ethernet systems. [5 Marks] d) Comment on the difference between the answers of parts b) and c).

Answer 1

Don't fragment NULL bit More fragment 16 bits | 32 bits = 4 bytes 09 OF. DF hl bits/ I bits & Bits Version HLEN Type of service 4 bits 4 bits 8 bits Identification 16 bits Time to Protocol leare 8 bits Header Checksum Total length Fragment Offset | Abyles Abytes 14 Bytes 16 bits 20 bytes 8 bits Abytes Source IP 32 bits Destination IP 32 bits Option 0 to 40 bytes DATA 32 bits IPv4 header

IPvG header Version Priority flow Label 4 bits Traffic Class/ 20-bits Pay wad Next Header Hop limit length 16 bits 8-bits 8 bits fixed header Source Address 128 bits Destination Address 198 bits Extension headerst

Comparision:

IPv4 header	IPv6 header
IPv4 header is complicated	IPv6 header is much simpler than IPv4 header.
The size of IPv4 header is smallerthan that of IPv6 header	The size of IPv6 header is much bigger than that of IPv4 header.
In IPv4 header, the source and destination IPv4 addresses are 32 bit binary numbers.	In IPv6 header, source and destination IPv6 addresses are 128 bit binary numbers.
IPv4 datagram headers are normally 20-byte in length. But we can include IPv4 option values also along with an IPv4 header.	In IPv6 header, we have a similar feature known as extension header
An IPv4 header has a variable length	An IPv6 header always has a fixed length of 40 bytes
Time-to-Live (TTL), a field in IPv4 header, typically used for preventing routing loops. is renamed to it's exact meaning, "Hop Limit".	Time-to-Live (TTL) is renamed to it's exact meaning, "Hop Limit" in IPV6.

IPv4 is running out of steam and companies are finally starting to switch to IPv6. IPv4 header was variable length. That was acceptable when routing was done by software. But now routers are built with hardware, and processing the variable length headers in hardware is hard. The large routers that allow packets to go all over the world are having problems coping with the load. Clearly, a new scheme was needed with fixed length headers.

An IPv6 header always has a fixed length of 40 bytes.One of the fields in the IPv6 header is the flow. A flow is a 20 bit number which is created pseudo-randomly, and it makes it easier for the routers to route packets. If a packet has a flow, then the router can use that flow number as an index into a table, which is fast, rather than a table lookup, which is slow. This feature makes IPv6 very easy to route.