11.11 Exercises

Using the guidelines presented in Section 11.4, recommend whether or not hierarchy should be introduced in the following shared-media networks:
1. A 10 Mb/s Ethernet network that bursts to a 9 Mb/s peak data rate
2. A 100 Mb/s FDDI network that supports a sustained data rate of 40 to 45 Mb/s
3. A 10 Mb/s Ethernet network that supports composite traffic flow F1, which consists of
  1. A client-server flow with a capacity of 400 Kb/s
  2. A distributed-computing flow with a capacity of 1.2 Mb/s
  3. A real-time video flow with a capacity of 2.7 Mb/s
Consider a network design in which there is an existing base of PCs and workstations with Ethernet interfaces. Current capacity requirements are beyond 10 Mb/s, and the customer wants to keep his or her investment in Ethernet NICs. The company is migrating from a shared network and is looking at IP routers, Ethernet 10 and 100 Mb/s switches, and LANE as possible options. Compare and contrast these options, disregarding capacity for the moment. Answer the following questions:
1. What distinguishing characteristics of the network design indicate each of these options?
2. What requirements of the network design would be needed to be better able to make a choice?
A customer wants to use LANE as a step to migrate the user devices with Ethernet interfaces to an RFC 2225 network. The devices will start with Ethernet NICs and migrate to having ATM OC-3c NICs in the RFC 2225 network, as shown in Figure 11.20.

Figure 11.20: LANE and RFC 2225 networks for Exercise 3.

Outline the design of the LANE network, showing all LANE servers (LECS, LES, BUS, SMS) and the connectivity between them and with the clients. Include how clients will be migrated from the LANE network to the RFC 2225 network as their NICs are upgraded from Ethernet to ATM OC-3c. What changes need to be made to device configurations as they are migrated to the RFC 2225 network?
For each of the following situations, would you recommend routing or switching? Explain your choices.
1. A workgroup of 100 workstations within a building using client-server applications and sharing a common IP subnet address.
2. Connecting your customer's LAN to the Internet via a dedicated T1 from an ISP.
3. A backbone between several organizations within a corporation. Each organization wants to be secure from the other organizations and requires that traffic is monitored between organizational boundaries.
For many hybrid mechanisms, traffic flows can have routed paths or switched paths, depending on the characteristics of each flow. Given the descriptions of switching and routing presented in this book, when would you recommend that a flow be switched, and when would it be routed? Present recommendations based on the following:
1. Duration of each flow in terms of the numbers of cell, frames, and/or packets
2. Type of each flow, by protocol or application
3. Performance requirements of each flow
4. Destination and/or source of each flow, as link-layer or network-layer addresses