Question

*2-  Describe the role of the communication layer, the network-wide state-management layer, and the network-control application layer in the SDN controller.

*3- Name the four different types of ICMP messages including type and code. What two types of ICMP messages are received at the sending host executing the Traceroute program?

*4- Why are different inter-AS and intra-AS protocols used in the internet? Explain your answer.

Answer 1

*2-Communication Layer: In a controller, this layer provides communication between the SDN controllerand controlled switches.

Network-wide state management layer: This layer acts as a set of network links, switches, and services.

Network-control application layer: This layer provides API and abstractions for network control apps.

*3-The four different types of ICMP messages are as follows:

1)Echo Reply, type 0, code 0

2)Destination Network unreachable, type 3,code 0

3)Destination host unreachable, type 3,code 1

4)Source quench(Congestion control), type 4,code 0

Two types of ICMP messages received at the sending host executing the Traceroute program are : ICMP warning message (type 11 code 0) and a destination port unreachable ICMP message (type 3 code 3).

*4-Border Gateway Protocol(BGP) is used for inter-AS( Autonomous System (AS) ) protocols.But, Router Information Protocol(RIP) and Open Shortest Path First(OSPF) protocol are used for intra-AS protocols.

Inter-AS protocol provides for the controlled distribution of routing information, but Intra-As protocol are the policy issues play a much less important role in choosing routes

Inter-AS protocol provides is dominates the quality and the performance, but Intra-As protocol focuses on the performance.

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