Top Down Network Design Chapter 10, Design Scenario The WVCC case study in this
ID: 3762460 • Letter: T
Question
Top Down Network Design
Chapter 10, Design Scenario
The WVCC case study in this chapter left some design decisions to the reader. In particu- lar, the case study doesn’t mention actual product selections made by the network designers. Making these selections is your job. Read through the case study and answer the following questions.
Please answer:
The work of an IT department is never finished. The WVCC network administrators
and student assistants have many plans for the next network upgrade. Their main con-
cern at this point is availability. Although the hierarchical mesh network has some re-
dundancy, there are many single points of failure. Availability of applications can be
adversely affected by any one of these points failing. Write a short paper that identi-
fies the most significant single points of failure in WVCC’s new network design.
Discuss the changes to the network design that you would make (or additional prod-
ucts that you would recommend) to avoid these single points of failure.
Explanation / Answer
Current Network at WVCC A few years ago, the college buildings were not even interconnected. Internet access was not centralized, and each department handled its own network and server management. Much progress has been made since that time, and today a Layer 2 switched, hierarchical network design is in place. A single router that also acts as a firewall provides Internet access. The logical topology of the current campus-backbone network at WVCC consists of a hierarchical, mesh architecture with redundant links between buildings. Figure 1 shows the logical topology of the campus backbone. Figure 1: current campus design (backbone design) 8. The campus network design has the following features: The network uses switched Ethernet. A high-end switch in each building is redundantly connected to two high-end switches in the Computing Center. Figure 2 shows these switches. Within each building, a 24- or 48-port Ethernet switch on each floor connects end user systems. Figure 3 shows the building network architecture. The switches run the IEEE 802.1D Spanning Tree Protocol. The switches support SNMP and RMON. A Windows-based network management software package monitors the switches. The software runs on a server in the server farm module of the network design. All devices are part of the same broadcast domain. All devices (except two public servers) are part of the 192.168.1.0 subnet using a subnet mask of 255.255.255.0. Addressing for end-user PCs and Macs is accomplished with DHCP. A Windows server in the server farm acts as the DHCP server. The email and web servers use public addresses that the state community college network system assigned to the college. The system also provides a DNS server that the college uses. The router acts as a firewall using packet filtering. The router also implements NAT. The router has a default route to the Internet and does not run a routing protocol. The WAN link to the Internet is a 1.544-Mbps T1 link. Figure 2: Building network design The physical design of the current network has the following features: Buildings are connected via full-duplex 100BASE-FX Ethernet. Within buildings, 100-Mbps Ethernet switches are used. Every building is equipped with Category 5e cabling and wallplates in the various offices, classrooms, and labs. The router in the Computing Center supports two 100BASE-TX ports and one T1 port with a built-in CSU/DSU unit. The router has a redundant power supply. A centralized (star) physical topology is used for the campus cabling. Underground cable conduits hold multimode fiber-optic cabling. The cabling is off-the-shelf cabling that consists of 30 strands of fiber with a 62.5-micron core and 125-micron cladding, protected by a plastic sheath suitable for outdoor wear and tear. Figure 3 shows the cabling design of the campus network.