Question

question 1) what is ICMP and at which layer of OSI reference model does it work? explain the process at Path Maximum Transmission Unit discovering utillising ICMP?
question 2) Give some advantages and disadvantages of :
a. Stateless Address Auto configuration in IPv6 (2.5 marks)
b. Stateful Address Auto configuration in IPv6 (2.5 marks)
question 3) . (a) What is the purpose of extension headers in IPv6? List the names of at least two extension headers used in IPv6. [2.5 Marks]
   (b) How are jumbograms used in the IPv6 environment? (2.5 marks)
question 4)  Compare and contrast the OSI reference model with the TCP/IP networking model. Which one do you think is more useful when working with and describing networks and why? [5 Marks]
question 5) In the context of securing TCP/IP environment, provide a brief discussion on typical TCP/IP attacks, exploits and break-ins [5 Marks]
question 6) Explain the three ways, route entries are placed in a routing table ?

Answer 1

1. ICMP(Internet Control Message Protocol) is an error reporting protocol for network devices like routers used to generate error messages to the source IP address when the network problems prevent delivery of IP packets. ICMP creates and sends messages to the source IP address indicating that a gateway to the internet that a router, service or host cannot be reached for packet delivery.

ICMP is not a transport protocol that sends data between systems.

ICMP works on the third layer of OSI reference model. ICMP is actually an integral part of IP. Network layer is the third layer of the OSI model. One of the functions of Layer 3 is internetworking which involves which involves logical addressing or Internet Protocol addressing.

For IPV4 packets, path MTU Discovery works by setting the Don't Fragment(DF) flag bit in the IP header of the outgoing packets. Then,any device along the path whose MTU is smaller than that of the packet will drop it, and send back an ICMP Fragmentation Needed(Type3,Code4) message containing its MTU, allowing the source host to reduce its Path MTU approximately.The process is repeated until the MTU is small enough to traverse the entire path without fragmentation.