Question

Answer the questions in full

1: What field in the IP header can be used to ensure that a packet is forwarded through no more than N routers?

2: Do routers have IP addresses? If so, how many?

3: Suppose you wanted to implement a new routing protocol in the SDN control plane. At which layer would you implement the protocol? Explain

Answer 1

1. TTL (Time To Live )

Explanation :

i)TTL (Time To Live ) Field is used to ensure that a packet would be forwarded upto limited number of hops .

ii) It is a 8 -bit field used to define the life time of a packet .

iii) Each router to which a packet is forwarded decrements the TTL value by 1 .

iv) If TTL value of a packet becomes 0 before reaching the destination , it would be discarded from the network.

v) It is a 8 bit field can be forwarded through max of 255 routers .

PFA of IP Header :

2.) Yes Routers have IP addresses.

Explanation :

i) Routers are special because they have two IP addresses assigned to each of its two interfaces .

ii) First interface is called WAN (Wide Area Network) interface which faces the internet has its public IP address.

iii) Second interface is called LAN (Local Area Network) interface which faces the home network's computers and has a private IP address.

3) Layer 3 i.e Network Layer as we are implementing a routing protocol

Explanation :

i) SDN control plane provides layer-2 MAC reachability and layer -3 routing information to routing devices for forwarding of packets .

ii) Layer 3 provides routing and reachability information to all participating devices , other conventional routing protocols are distributed , while an SDN based system typically involves downloading controller - derived layer 3 forwarding tables to various devices using standardized or open protocols .

If you like please give thumbs up :)