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

2. 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)

3. 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

4. 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

5. 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

6. Physical diagram
Sample-network-diagramCC

7. 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

8. Logical network diagram
Router
Switch
Address
range
Wireless access point

9. 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

10. 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
These are hard to deal with
Use dotted-decimal notation

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

12. 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

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

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

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

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

17. Transmission on a different network
Device sends to
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

18. 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

19. tracert – command line
Shows the addresses a packet goes through

20. 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
– (16 million)
– (64 thousand)

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

22. 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

23. 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

24. ipconfig /all command
Shows the IP information for a device

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

26. 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

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