ECET 465 Homework week2
Chapter 4 Review Questions
R2. What are the two most important network layer functions in a datagram network?
What are the three most important network layer functions in a virtual circuit network?
R4. Do the routers in both datagram networks and virtual circuit networks use for warding tables? If so, describe the forwarding tables for both classes of networks.
R6. List some applications that would benefit from ATM’s CBR service model.
R8. Three types of switching fabrics are discussed in Section 4.3. List and briefly describe each type.
R10. Describe how packet loss can occur at output ports.
R12. Do routers have IP addresses? If so, how many?
R15. Suppose there are three routers between a source host and a destination host. Ignoring fragmentation, an IP datagram sent from the source host to the destination host will travel over how many interfaces? How many forwarding tables will be indexed to move the datagram from the source to the destination?
R19. Compare and contrast the IPv4 and the IPv6 header fields. Do they have any fields in common?
R20. It has been said that when IPv6 tunnels through IPv4 routers, IPv6 treats the IPv4 tunnels as link-layer protocols. Do you agree with this statement? Why or why not?
Chapter 4 Problems
P2. Consider a virtual circuit network. Suppose the VC number is an 8-bit field.
What is the maximum number of virtual circuits that can be carried over a link?
Suppose a central node determines paths and VC numbers at connection setup. Suppose the same VC number is used on each link along the VC’s path. Describe how the central node might determine the VC number at connection setup. Is it possible that there are fewer VCs in progress than the maximum as determined in part (a) yet there is no common free VC number?
Suppose that different VC numbers are permitted in each link along a VC’s path. During connection setup, after an end-to-end path is determined, describe how the links can choose their VC numbers and configure their forwarding tables in a decentralized manner, without reliance on a central node.
P5. Consider a VC network with a 2- bit field for the VC number. Suppose that the network wants to set up a virtual circuit over four links: link A, link B, link C, and link D. Suppose that each of these links is currently carrying two other virtual circuits, and the VC numbers of these other VCs are as follows: