Design Unit 26 Design a small or home office network HND in Computing and Systems Development

Timeline Week Activity 1 10 LO2 Devices, Bandwidth, Users 2 11 LO2 Applications, Scaling, Security 3 12 Assignment 2 LO2 4 13 LO3 Device installation 5 Introduction 14 LO3 Network installation 6 LO1 Capacity 15 LO3 Testing 7 LO1 Usage 16 L04 User access, maintenance 8 LO1 Security 17 LO4 Improvements 9 Assignment 1 LO1 18 Assignment 3 LO3 & 4 (mostly witness)

Learning outcome 2 Be able to design small or home office networks Devices: number of connected devices; anticipated participation Bandwidth: average load; peak load; local Internet availability; cost constraint Communications plan from lesson 2 Users: quality expectations; concept of system growth Applications: requirements eg security, quality of service Communications: considerations eg suited to devices, suited to users, lifestyle preferences, commercial requirements Scalable: considerations eg supporting device growth, supporting additional devices, bandwidth use trend change Security: considerations eg addressing policy, device participation, firewall rules, encryption preference

LO2 Assessment criteria 2.1 Design a small or home office network solution to meet a given specification 2.2 Evaluate the design and analyse user feedback

Physical and logical design A physical design network diagram shows the nodes and connections amongst nodes in a computer network Shows the devices Can relate to a building diagram to show their location as well as the connections

Physical diagram Sample-network-diagramCC

Logical network diagram The logical diagram shows the network architecture Domain names Server roles IP addresses assigned to servers or clients DHCP settings, such as the default gateway, Lease address ranges

Logical network diagram Router Switch Address range Wireless access point

Domain name MWS will need a domain name for their web site and for internal usage As an example our domain is computing.hct.ac.uk Home page of the wiki You need to decide on a domain name for MWS

IP addressing (simplified) TCP/IP protocol Each device has an IP address to identify it on the network IP addresses are 32 bit binary numbers 11000000101010000111101110000100 These are hard to deal with Use dotted-decimal notation

Dotted decimal Split into groups of 8 11000000.10101000.01111011.10000100. Covert each octet (group of 8 bits) into decimal 192.168.123.132 This is how we normally represent an IP address

Network and host The IP address consists of 2 parts The network address – the network a device is a member of The host address – the address of the device on the network But which part is which in an IP address? The subnet mask will tell us

Subnet mask The network address is192.168.123.0 The host address is 0.0.0.132 The subnet mask tells the computer where to split the IP address The subnet mask for this to work has to be 255.255.255.0 Which is 11111111.11111111.11111111.0000000

Deriving the addresses Line up the IP address and the subnet mask together 11000000.10101000.01111011.10000100 11111111.11111111.11111111.00000000 The 1s in the subnet mask identify the network address The 0s in the subnet mask identify the host address

How does it work When a packet arrives at the 192.168.123.0 network, the computer just looks at the last octet and transmits the packet to the device at 192.168.123.132 on the same network

Transmission on the same network Device 192.168.123.132 sends to 192.168.123.7 The computer uses the subnet mask to compare the destination network address with its own network address They match so it transmits to 192.168.123.137

Transmission on a different network Device 192.168.123.132 sends to 212.58.244.18 The computer uses the subnet mask to compare the destination network address with its own network address They don’t match so it transmits to the default gateway This is the address of a router

The router The router forwards packets between networks When a data packet arrives, the router reads the address in the packet Using information in its routing table it directs the packet to the next network A packet is forwarded from one router to another through the internet until it reaches its destination

tracert – command line Shows the addresses a packet goes through

Reserved addresses Private network addresses allow duplicate addresses, so long as they are never allowed on the internet So the BBC can have a device with the same address as us, so long as they are both hidden from the internet 10.0.0.0 – 10.255.255.255 (16 million) 192.168.0.0 – 192.168.255.255 (64 thousand)

Small local network addressing The range 192.168.0.0 to 192.168.0.255 has 256 unique addresses 192.168.0.0 is invalid as it does not have a host address 192.168.0.255 is reserved for broadcasting packets to every device on the network So there are 254 available addresses

Static and dynamic addresses Static addresses are fixed, but have to be set on each device Used on servers, routers, printers, back up devices The router address is the default gateway Dynamic addresses are allocated each time a device connects to the network A DHCP server is required to allocate addresses

DHCP Dynamic Host Configuration Control When a device connects to the network its DHCP client software issues a broadcast request to any available DHCP server The server responds with an allocation of an IP address ( a lease) for a specific period of time The address comes from a pool (or range) of addresses set by an administrator Used to avoid setting up on each device (allows imaging) Used for mobile devices connecting on several networks

ipconfig /all command Shows the IP information for a device

A logical network diagram Needs to show: The domain name Device static addresses Dynamic address ranges Default gateway

Activity 1 Draw a physical diagram for MWS MWS offices are in the top floor of a converted machinery shed. Their CNC equipment is on the ground floor Use the case study information your results from the device choice activity in lesson 1 your communication plan from lesson 2 your client-server knowledge Include clients, switches, routers, access points, servers, firewalls, printers, CNC as appropriate

Activity 2 Draw the logical network diagram for MWS Make sure you include all the devices