Lecture

Week 4 Lesson Plan Addendum



Networking Lecture

Signaling Methods


IEEE standards

802.1 – LAN, MAN management m- Spanning Tree Algorithm (prevents bridge looping) – multiple paths between bridges enable cycling of packets forever

802.2 – LLC standards – Divides LLC in MAC and network sub layers

802.3 – Specifications for CSMA/CD

802.4 – Token Bus Standards

802.5 – Token Ring Standards

802.6 – Larger Network Standards – like MANs

802.7 - Broadband Standards

802.8 – Fiber Optic Standards

802.9 – Voice and Data (VOIP) Standards and Transmission

802.10 – LAN Security

802.11 – Wireless Standards

802.12 – 100VG AnyLAN – newest high speed LAN technology


Signaling Methods

Analog

Digital Signals – conversion from analog to digital done by sampling – demonstrate

Baseband – digital - one signal over entire channel

Broadband – analogue unidirectional signaling – 2 wires tx and rx

Multiplexing Multiplex devices required on both ends of signal path

FDM – frequency division multiplexing

TDM – time division multiplexing

DWDM – different wavelengths of light – different colors are encoded with different data streams – merged into white light beam and them prismed out on the other end.


Clocking – Synchronous Sender and receiver – uses start bits to identify data

Simplex communication is unidirectional – like TV or radio

Half duplex is – unidirectional at any given moment but communication can be both ways just at different times – walkie talkie

Full duplex is bidirectional communication at same time – telephone


Interference in communication  - Demonstrate

EMI

RFI

Crosstalk

Attenuation

Local Area Networks architecture models

Ethernet – 10base2 – implements CSMA/CD also called thinnet – uses coaxial cable about the size of TV cable. Easy to install but uses terminators on ends of cable – uses a tee connector – bayonet style connector – has a 30 node limitation – 100m bps max speed.


Ethernet – 10base5 – also called thicknet – uses vampire taps – transceiver units  (like what we use on routers called AUI connector) – 15 pin cable to NIC card – Partial EMI protection – hard to pin without shorting entire cable – expensive – not used very much but there are some special applications where EMI is a factor.


Ethernet -10baseT – Twisted pair cabling used – UTP (unshielded) and STP (shielded) contain 8 wires – use RJ45 connectors – uses insulation displacement as means of contact between wire and connector – subject to all major interference factors – described as CAT 3, 5, 5e, or 6 – CAT 3 is house phone wiring – CAT 5 is standard Ethernet cabling – CAT 5 E is Ethernet cabling with higher speed and CAT 6 is Ethernet with some shielding for interference protection. Speed is 10 mbps below CAT 5 and 100m bps CAT 5 or above.



Ethernet – 100basex – fast Ethernet can be 100baset CAT 5 cabling – best EMI protection but expensive

Ethernet – 1000baseT – Gigabit Ethernet – 1 G bps speed – 7 times the speed of a T1

Ethernet – 100basefl – fiber optic Ethernet


CMSA/CD – Collision Dectection









Node Limitation in Ethernet Networks – 5-4-3 rule

5 - maximum number of segments

4 – maximum number of repeaters between segments

3 – maximum number of segments that can have computers attached (other two segments can be cable extenders only)

Maximum number of nodes per segment is 100 – NOTE: routers and hubs negate this rule





Ethernet frame structure (note – token frame is the same but has start bit, access control (who owns token) and an end bit.





Our Network we build in class





Token Ring





The first computer in line is the network monitor – keeps track of who has token )a bit of software that enables or disables transmission onto the cable). Packet is passed from computer to computer – a computer can only transmit on network when it has the token. Then it oases the token to next computer in line.


Uses MAUI hubs




Actually in a physical sense – it is laid out in the same shape as a star network where the cables from the computers come together into a device called an MAUI. The ring connectivity actually occurs within the MAUI.


These are rare networks but they still do exist – maintenance is similar to a 10baseT network.


Plenum ratings – area above false ceilings or below false floors is deadly should a fire occur (poisonous insulation gases) – cables regulations determine that plenum rated cabling be used in such areas due to toxicity of smoke – plenum rated means that they burn slower and produce less toxic smoke – harder to connectorise and not as flexible to turn corners


Haylon systems are used to suppress fire in computer areas – douses fire by chemically combining with all the oxygen in the area. Human live ceases after 30 seconds – if Haylon system goes off – get out immediately.


FDDI Fiber Data Distributed Interface

Built on the Token Ring style – with a software token sent to each computer in turn to give permission to transmit on the network. Used mainly for large MAN or very large LANs – speed of 100mbps – uses dual ring for redundancy Has primary and secondary rings – computers can connect to either ring. Maximum of 500 computers per ring – 62 mile limited without repeaters – same frame structure as token ring – excellent transmission for high bandwidth applications such as engineering drawings, medical data (x-rays, and such).


AppleTalk  - proprietary and used only on Mac networks – uses STP – addressing scheme uses zones – each computer uses a previously stored address or assigns itself a new one – good only for small networks – Macintosh computers can also connect through NIC cards to an Ethernet network at the same time. Connectivity through the Ethernet over AppleTalk is also available. Macs mostly going to Ethernet nowadays.


Arc net – forget it


Wireless – more on that later – becoming more affordable and easier to manage and configure. Wave of the future – uses Radio Frequency – also can use Microwave towers or even satellite connectivity.