Data Communication Networks Quiz 4

  1. An ATM switch contains only two layers, the physical and ATM. Why?

    2. Answer: The switch only needs to receive and resend the cell (physical layer) and examine and alter (if needed) the header (ATM layer). It does not change or read the information in the 48-byte information field!

  2. What is the difference between NNI and UNI.

    3. Answer: UNI is the User-to-Network Interface, whereas NNI is the Network-to-Network Interface. The UNI connects the user to the network and the NNI is the interface between network nodes (switches).

  3. Assume a header with VPI 7 is coming in on port "a" to a switch given the following routing table. What is the new ATM cell like? Draw it (as in class).

Routing Table

VPIin

Portin

VPIout

Portout

6

a

6

w

7

a

7

x

7

b

8

y

6

b

9

z

 

Answer:

I

VPI = 7

  

I

VPI = 7

Incoming Port = a

  

Outgoing Port = x