Question

1. Explain how IPv4 route decisions are made. Provide at least two examples.

2. Review an IPv4 header and discuss the different fields and what each field does.

3. Compare and contrast the major differences between IPv4 and IPv6. Your write-up should include the following details:

• Header details
• Datagram size
• How decisions are made
• How addresses are assigned

Answer 1

Route decisions are based on topology information such as neighbor nodes, reachable nodes etc...but not on precise location information.

An IPv4 header is a prefix to an IP packet that contains information about the IP version, length of the packet, source and destination IP addresses, etc. It has the following fields:

a.Version – the version of the IP protocol. For IPv4, this field has a value of 4.

b. Header length – the length of the header in 32-bit words. The minumum value is 20 bytes, and the maximum value is 60 bytes.P

C. Priority and Type of Service – specifies how the datagram should be handled. The first 3 bits are the priority bits.

d. Total length – the length of the entire packet (header + data). The minimum length is 20 bytes, and the maximum is 65,535 bytes.

e. Identification – used to differentiate fragmented packets from different datagrams.

f.Flags – used to control or identify fragments.F

g. Fragmented offset – used for fragmentation and reassembly if the packet is too large to put in a frame.

h. Time to live – limits a datagram’s lifetime. If the packet doesn’t get to its destination before the TTL expires, it is discarded.

i.proyocol – defines the protocol used in the data portion of the IP datagram. For example, TCP is represented by the number 6 and UDP by 17.

J.header checksum – used for error-checking of the header. If a packet arrives at a router and the router calculates a different checksum than the one specified in this field, the packet will be discarded.

K.Source IP address – the IP address of the host that sent the packet.

L. Destination IP address – the IP address of the host that should receive the packet.O

m. Options – used for network testing, debugging, security, and more. This field is usually empty.

Comparing ip4 and ip6:

a.Ipb4 is 32 bit snd ipv6 has, 129 bits

b.Ip4 is a numeric addressing and ipv6 is alpha numeric

c.In ipv4 the binary bits are seperated by a dot where as in ipv 6 it is seperated by a colon.

d.The size of ipv6 much bigger than that of ipv4 header because of ipv6 address size.

e.Ipv4 datagram. Is larger than 576 bytes.ipv6 a host must be able to process a datagramt least as large as the. MTU of the link to which it is attached.