1. (a) Give one reason why it is often more convenient or efficient for routing
ID: 3581247 • Letter: 1
Question
1. (a) Give one reason why it is often more convenient or efficient for routing to be hierarchically provider-based, using CIDR – that is, routing is first to the destination provider and then to the final destination – than to use the original class A/B/C mechanism..
(b). What is the purpose of the AS-path attribute in BGP? What role does it play in routing decisions?
2. (a) Suppose a TCP connection from A to B opens and then closes. It immediately re-opens, using the same port numbers. Describe how an old duplicate could result in bad data accepted by the second connection, and explain how TIMEWAIT helps prevent this.
(b). TIMEWAIT also helps with the problem of the lost final ACK. Explain how
Explanation / Answer
1. a) As CIDR utilizes the ip addresses in much effficient way than class full addressing(A/B/C).
b) AS-path is a path that connects the nodes with AS number and makes them the neighbors. The main purpose of it is to avoid loops.Without the BGP will be just RIP as both uses distance vector routing algorithm.
2. a) when the connection opens, closes and opens immediately this is called as passive close and the there may be some data which will be left unlceared with respect to the first connection which may result as the bad data for the second connection. TIMEWAIT prevents this by not terminating the connection complete and resuming the same connection back then it would not be anymore new connection with the old data.
b) It helps in lost final ACK as the TIMEWAIT state hold close state for almost 4 mins. If any positive acknowledgment or active acknowledgment is not heard from the other end point then it helps closing the connection. In lost final ACK case if the final ACK is lost the connection is left open waiting for the acknowledgement.
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.