Quality of Service

Question 1

What are the sources of delay?

Answer 1

Processing delay
Queueing delay
Propagation delay
Serialization/transmission delay

Question 2

What mechanisms exist to support qos?

Answer 2

Scheduling:
Fifo queues
Priority scheduling
Weighted fair queueing

Policing: shaping (limit ingress - avg brust rate, burst rate)

Signalling

Question 3

Describe the scheduling and policing mechanisms for qos

Answer 3

Fifo: discard strategy:
Tail drop (drop last)
Priority drop
Random drop

Priority scheduling:
High & low prio queues

Question 4

Why do we use policing mechanisms?

Answer 4

Limit traffic to not exceed declared params
Avg rate
Peak rate
Burst size (max num of consecutive packets)

Question 5

What is a token bucket (qos)

Answer 5

A bucket that keeps tokens. Packets cna only be processed if a token can be aquired first. Via the token generation, the rate cna be controlled. Can define an upper bound

Question 6

Where do we maybe continue?

Answer 6

Diffserv architecture