What is a network?
A network is created when you have two or more hosts connected together
so that they can communicate and share resources.
- A host can be any device which has a "network interface" which alows it to connect to other devices on a network.
- Some examples of resources which can be shared are documents and printers
What are some different type of Networks?
LAN - Local Area NetworkTypically refers to a network contained within a building
- WAN - Wide area NetworkA network spread over a wide area, typically covering multiple cities and countries
- CAN - Campus Area NetworkA network spread betweeen multiple contiguous buildings.
How do we make connections?
Network hosts communicate with each other by sending bits of information across network media.
Network media can be wired or wireless.
Examples of wired media are copper and fiber optic.
Examples of wireless media are RF and infra-red.
What is a Protocol?
A protocol is a set of rules and procedures for communication.
In order for hosts to communicate on a network they must agree to use a common set of rules and procedures or in other words, must use the same network protocol.
Some of the common network protocols used today are TCP/IP, IPX/SPX, NETBEUI, and appletalk.
Introduction to Addressing
All hosts on a network must be identified with an address on that network.
Addressing in computer networks is similar to how addressing works with the postal network or telephone network.
The most typical types of addresses used in computer networking are MAC addresses and IP addresses.
There are both provate and public forms of addressing.
- Private addressing is used to keep communications safe within the boundaries of a private secure network.
- Public addressing is used to allow communications with the outside world, most typically known as the internet.
- Unshielded twisted pair capable of speeds up to 10Mbit/s. Used with 10Base-T, 100Base-T4, and 100Base-T2 Ethernet.
- Unshielded twisted pair capable of speeds up to 20Mbit/s. Not widely used. Used with 10Base-T, 100Base-T4, and 100Base-T2 Ethernet.
- Unshielded twisted pair capable of speeds up to 100Mbit/s. May be used with 10Base-T, 100Base-T4, 100Base-T2, and 100Base-TX Ethernet.
- Enhanced Cat 5 is similar to CAT5, but exceeds its performance. Improved distance over previous categories from 100m to 350m. May be used for 10Base-T, 100Base-T4, 100Base-T2, 100BaseTX and 1000Base-T Ethernet.
- Can transmit data up to 220m at gigabit speeds. It has improved specifications for NEXT (Near End Cross Talk), PSELFEXT (Power Sum Equal Level Far End Cross Talk), and Attenuation. Cat 6 is backward compatible with lower Category grades and supports the same Ethernet standards as Cat 5e.
- Multimode Fiber
- Multimode fibers have large cores. They are able to carry more data than single mode fibers though They are best for shorter distances because of their higher attenuation levels.
- Single Mode Fiber
- Single Mode fibers have a small glass core. Single Mode fibers are used for high speed data transmission over long distances. They are less susceptible to attenuation than multimode fibers.
- RG59 and RG6
- These are both shielded coaxial cables used for broadband networking, cable television, and other uses.
- A serial cable is a cable that can be used to transfer information between two devices using serial communication, often using the RS-232 standard.
Typically use D-subminiature connectors with 9 or 25 pins. Cables are often unshielded, although shielding cables may reduce electrical noise radiated
Wired Media - Twisted Pair
All categories can travel up to 100 meters before suffering from decrease in sgnal.
- CAT3: 10 Mbps
- CAT5: 100 Mbps
- CAT5e: 1000 Mbps
- CAT6: 1000 Mbps
- UTP: Unshielded Twisted Pair
- - Susceptible to EMI
- STP: Shielded Twisted Pair
- - Differs from UTP in that it has a foil jacket that helps prevent cross talk. Cross talk is signal overflow wire.
- - Uses an RJ45 connector
What is Plenum?
Plenum grade cable should always be used in a plenum space.
- An enclosed space used for airflow.
- Usually thought of as the space above a drop ceiling or below a raised floor.
LAN Technology Types-Ethernet
Ethernet is known as the 802.3 standard.
Ethernet uses the CSMA/CD access method
Ethernet is the most widely-installed local area network ( LAN) technology.Specified in a standard, IEEE 802.3.Early ethernet networks uses coaxial connections.
The most common types currently use twisted pair cabling, however, fiber optic cabling is becoming much more common as standards and speeds increase.
LAN Technology Types
CSMA/CD (Carrier Sense Multiple Access with Collision Detection)
In the early days of ethernet, when two hosts would send packets at the same time, a collision would occur.
A standard had to be created that would have the hosts follow rules relating to when they could send data and when they could not.
This standard is Carrier Sense Multiple Access with Collision Detection, referred to as CSMA/CD.
CSMA/CD forces computers to “listen” to the wire before sending in order to make sure that no other host on the wire is sending.
If a collision is detected, both of the senders will send a jam signal over the Ethernet.
This jam signal indicates to all other devices on the Ethernet segment that there has been a collision, and they should not send data onto the wire
The TCP/IP Protocol Suite
TCP/IP stands for the Transmission ControlProtocol/Internet Protocol.
It is the basic communication protocol of the Internet.
Although it was designed to be an Internet protocol, it can also be used as a communication protocol in a private network
The TCP/IP architecture is based off the 4 layer DARPAmodel.
Each layer of the DARPA model corresponds toone or more of the layers of the 7 layer OSI model.
Each of the 4 layers have individual protocols which allwork together to form a protocol stack.
Transport Layer Protocols
TCP – Transmission Control Protocol
- TCP breaks data into manageable packets and tracks information such as source and destination of packets. It is able to reroute packets and is responsible for guaranteed delivery of the data.
- – Reliable Communication
- UDP – User Datagram Protocol
- A connectionless, datagram service that provides an unreliable, best-effort delivery.–Unreliable Communications.
Internet Layer Protocols
IP – Internet Protocol
This is a connectionless protocol, which means that a session is not created before sending data.
IP is responsible for addressing and routing of packets between computers.
It does not guarantee delivery and does not give acknowledgement of packets that are lost or sent out of order as this is the responsibility of higher layer protocols such as TCP.
- ARP – Address Resolution Protocol
Provides IP-address to MAC address resolution for IP packets.
A MAC address is your computer's unique hardware number and appears in the form 00-A0-F1-27-64-E1 (for example).
Each computer stores an ARP cache of other computers ARP-IP combinations.
Internet Layer Protocols continued..
- ICMP – Internet Control Message ProtocolInternet Control Message Protocol enables systems on a TCP/IP network to share status and error information such as with the use of PING and TRACERT utilities.
PING & TRACERT are used for diagnostic and error reporting
- IGMP – Internet Group Management Protocol
- Internet Group Management Protocol is used to manage Internet Protocol multicast groups.IP hosts and adjacent multicast routers use IGMP to establish multicast group memberships.IGMP is only needed for IPv4 networks, as multicast is handled differently in IPv6 networks.
Working with IP Addresses
- What is an IP Address?
- –A 32 bit address that is used to uniquely identify a computer on anetwork
.–The Network ID portion of the IP Address identifies the networkwhere the computer sits.
–The Host ID portion of the IP Address uniquely identifies th ecomputer on its network.
Example:IP Address: 192.168.10.1Network ID Host ID
Planning an IP Addressing Scheme
How to Plan an IP Addressing Scheme
–How many IP Addresses do you need today?
–How many IP Addresses will you need in the future?
- –Are you dealing with a pre-existing IP scheme?
Rules for IP Addressing
Each of the 4 numbers in an IP Address is called an octet (8bits).–192.168.10.101
A bit is a 1 or a 0
Each octet can only have a number from 0 to 255–00000000 = 0–11111111 = 255
The first octet cannot be 127
The 127 range has been reserved for diagnostics.
127.0.0.1 is known as the loopback address. (It is sometimes also referred to as local host.)
Rules for IP Addressing continued..
- The Host ID cannot be all 0s or all 255s
- –All 0s represents the Network ID
- –All 255s is the broadcast address