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Internet Engineering Course

Network Design


• Define and analyse an organization
network requirements
• Discuss about the appropriate solutions
– Identify important factors in network design
– Find appropriate structure

Internet Engineering Course; Sharif University of Technology

system and network access • Ease of configuration • Management Internet Engineering Course. Sharif University of Technology .Design considerations • Budget • Nature of applications • Availability of expertise • Fault tolerance in terms of applications.

Small sized Network (<80 users) • Low budget for IT expense • Little expertise in various technologies • Mostly off the shelf applications – Low bandwidth consumption • Mostly basic requirements. such as email. connecting new devices. printing and file sharing • One or two administrators – Responsible for every aspects of network (generalist) – Server management. backup tasks. installation of workstations and troubleshooting PC problems Internet Engineering Course. word processing. Sharif University of Technology .

Sharif University of Technology .Requirements for SSN • Low cost equipment • Shared bandwidth for most users. switched for a selective few • A central switch acting as a backbone • Flat network design • Little fault tolerance • Minimal management required • High growth provisioning of 20-50% Internet Engineering Course.

A sample firm • Connect 50 users to a network • Connect 10 printers to the network • Connect the company’s database and internal e- mail services to the network. hosted in a windows NT server • Users require connectivity to the internet • Several system require access to external email. Sharif University of Technology . the Web and FTP connectivity • A future web site may be implemented Internet Engineering Course.

Sharif University of Technology . power users group and non power users • Power group need to print a lot of documentation.Connectivity design • The aim is to have a design that is both cost effective and provisioned for future expansion • There is a server room with all the connecting devices and servers • The printers are fitted with built in Ethernet ports distributed in the building • There are two groups of users. take large documents from server or save presentation files into the server Internet Engineering Course.

Connectivity design (cont.) • Non power users do more manual tasks such as answering phone calls • They use the network mainly for reading emails and do some simple word processing • They use low-end PCs Internet Engineering Course. Sharif University of Technology .

Physical diagram Internet Engineering Course. Sharif University of Technology .

Sharif University of Technology .Physical diagram – expansion plan Internet Engineering Course.

Logical network design Internet Engineering Course. Sharif University of Technology .

Sharif University of Technology .Network management • Because of tight budget it is hard to have a dedicated network management workstation • The simplest way is to select switch and hub devices that have web interface Internet Engineering Course.

1.168.255 • Dynamic or Static IP assignment? – It might be hard and maintain a DHCP server – Therefore for small sized network we may decide to use static IPs. • How about a DNS server? – Again setting and maintaining a DNS for this size of network may not be beneficial – Therefore a simple naming scheme maybe used Internet Engineering Course.1.0 to 192. Sharif University of Technology .168.Addressing and Naming • For this size of network a Class C address should be used. • A private Class C address is used: 192.

there is a need for NAT functionality – There exists the advantage of security of network • It is decided to use a router with built-in NAT functionality • It is not cost effective to host email and Web service inside the organization • Therefore such servers are outsourced Internet Engineering Course.Connecting the network to the Internet • In the design we used private IP addresses: – Computers can’t use Internet directly. Sharif University of Technology .

Medium sized Network (<500 users) • Fixed annual budget for IT expenditure • MIS department taking care of the information system • Develop own in-house applications • Availability of one or a few dedicated network engineers • Invest in server/host fault tolerance features • May provide dial-in service to mobile workers Internet Engineering Course. Sharif University of Technology .

accessing the host for in-house developed applications – MIS – development of applications on AS/400 – Human Resources – Mainly word processing – Engineering – make use of CAD/CAM workstations Internet Engineering Course. each with its own applications: – Marketing – mainly email with external customers. calendaring. presentation applications – Customer support – mainly handling customer queries. word processing. Sharif University of Technology .A sample firm • Connecting 300 users to a network • The company has a AS/400 host and 8 Windows NT file servers • There are 6 departments in the company.

such as the Engineering department. all the servers are • connected to the backbone switch at 100 Mbps. • Since Customer Support and Human Resources users require fewer computing resources. they will be connected to the 10 Mbps switch in a ratio of 16 users to a switch. Sharif University of Technology . will have 100 Mbps switched connections to the desktop • Because Marketing users deal with graphics presentation. they are connected to the 10 Mbps switch in a ratio of 24 to a switch. • Except for the server in the Engineering department. Internet Engineering Course. The engineering server is connected to the switch in the Engineering department at 100 Mbps.Connectivity design • Power users.

Physical diagram Internet Engineering Course. Sharif University of Technology .

Sharif University of Technology .Logical network design Internet Engineering Course.

) • With a network of this size it is beneficial to have a DHCP server • Also it is better to have a DNS for name resolution: Internet Engineering Course.Logical network design (cont. Sharif University of Technology .

Remote access • 15 dial-in users • 8 maximum concurrent dial-in connections • A dial-back service will be implemented. a remote user initiates a call to the router and triggers the router to dial back to the user. That is. • Remote users have to authenticate themselves through a login ID and a password. Sharif University of Technology . Internet Engineering Course.

Internet Engineering Course. • Organizational domain name must be registered • To reduce WAN traffic. the services server hosting FTP. the primary DNS server. These would be for the organizational firewall.Addressing and Naming • There is a requirement for three public addresses to be obtained from the organization’s ISP. HTTP and e-mail services. the primary DNS server may be placed on the ISP site. Sharif University of Technology . • All these servers should have their IP addresses assigned statically.

Sharif University of Technology . • Fault tolerance features for mission-critical applications. IPX. • Substantial amount of company’s annual budget is spent on IT investment. such as hardware redundancies. SNA or NetBIOS. Internet Engineering Course. • token-ring. network path redundancies and extensive investment on backup services. • Fairly large MIS department to take care of the information system • In-house application development teams that constantly look at the deployment of new Internet technologies such as Java and multimedia applications.Large size network (>500 users) • Internetwork of networks. FDDI and ATM. • Availability of experts in areas such as system management. with a mix of technologies such as Ethernet. • Involves multiprotocol such as TCP/IP. network infrastructure and management.

Sharif University of Technology .Physical diagram Internet Engineering Course.

Sharif University of Technology .CE site physical design Internet Engineering Course.

Paolo Borghi. Sharif University of Technology . Kok-Keong Lee.Reference • IP Network Design Guide. Martin W. Payam Motallebi. Murhammer. Karl Wozabal Internet Engineering Course.