1. Topics
Network Topology
Cables and connectors
Network Devices

2. Network Topologies LANs and WANs - Geographical coverage LANs WANs
A single geographical location, such as office building, school, etc
Typically High speed and cheaper.
WANs
Spans more than one geographical location often connecting separated LANs
Slower
Costly hardware, routers, dedicated leased lines and complicated implementation procedures.

3. Network Topologies Topology - Physical and logical network layout
Physical – actual layout of the computer cables and other network devices
Logical – the way in which the network appears to the devices that use it.
Common topologies:
Bus, ring, star, mesh and wireless

4. Bus topology
Uses a trunk or backbone to which all of the computers on the network connect.
Systems connect to this backbone using T connectors or taps.
Coaxial cablings ( 10Base-2, 10Base5) were popular options years ago.

5. Bus Topology Advantages Disadvantages Cheap and easy to implement
Network disruption when computers are added or removed
Require less cable
A break in the cable will prevent all systems from accessing the network.
Does not use any specialized network equipment.
Difficult to troubleshoot.

6. Ring Topology Logical ring
Meaning that data travels in circular fashion from one computer to another on the network.
Typically FDDI, SONET or Token Ring technology are used to implement a ring network
Ring networks are most commonly wired in a star configuration
Token Ring has multi-station access unit (MSAU),equivalent to hub or switch. MSAU performs the token circulation internally.
To create the complete ring, the Ring In (RI) port on each MASU is connected to the Ring Out (RO) port an another MSAU. The last MASU in the ring is then connected to the first, to complete the ring.
FDDI: Fiber Distributed Data Interface

7. Ring Topology Advantages Disadvantages
Cable faults are easily located, making troubleshooting easier
Expansion to the network can cause network disruption
Ring networks are moderately easy to install
A single break in the cable can disrupt the entire network.

8. Star Topology
All computers/devices connect to a central device called hub or switch.
Each device requires a single cable
point-to-point connection between the device and hub.
Most widely implemented
Hub is the single point of failure

9. Star Topology Advantages Disadvantages
Easily expanded without disruption to the network
Requires more cable
Cable failure affects only a single user
A central connecting device allows for a single point of failure
Easy to troubleshoot and isolate problems
More difficult to implement

10. Mesh Topology Each computer connects to every other.
High level of redundancy.
Rarely used.
Wiring is very complicated
Cabling cost is high
Troubleshooting a failed cable is tricky
A variation hybrid mesh – create point to point connection between specific network devices, often seen in WAN implementation.

11. Mesh Topology Advantages Disadvantages
Provides redundant paths between devices
Requires more cable than the other LAN topologies
The network can be expanded without disruption to current uses
Complicated implementation

12. Wireless networking Do not require physical cabling
Particularly useful for remote access for laptop users
Eliminate cable faults and cable breaks.
Signal interference and security issue.

13. Wireless networking Advantages Disadvantages
Allows for wireless remote access
Potential security issues associated with wireless transmissions
Network can be expanded without disruption to current users
Limited speed in comparison to other network topologies

14. Cabling and Connectors
General media considerations
Broadband versus baseband
Baseband transmissions use digital signaling and Time Division Multiplexing (TDM)
Broadband transmissions use analog and Frequency Division Multiplexing(FDM)
Dialog modes: Simplex, half duplex and full duplex
EMI: is a problem when cables are installed near electrical devices, such as air conditions or fluorescent light fixtures.
Crosstalk: refers to how the data signals on two separate media interfere with each other.

15. Cabling and Connectors
Media interference
Electromagnetic interference (EMI) and cross talk
Network media vary in their resistance to the effect of EMC.
UTP is susceptible and fiber is resistant
Attenuation
Resistance :Coaxial cable > UTP, STP > UTP, Fiber > all
Maximum distance
Repeaters
Attenuation-related problems require a network analyzer to detect
Bandwidth
Transmission capacity of a media
Data throughput is measured in bits per second(bps), Mbps, and Gbps
For today’s application-intensive networks, Old 10Mbps is not enough, 100Mbps is very common and 1000Mbps is used too.

16. Network Media Cable-based media Coaxial Twisted pair Fiber-optic
Copper wire to conduct the signals electronically
Was the choice for LAN for many years.
Retiring
Twisted pair
Copper wire to conduct too
Most widely used
Fiber-optic
transmits the signals as light
Uses glass or plastic conductor and
High Cost. Restricted to where segment length and higher speeds are needed.
Server room, backbone
Carry signals between computers: Cable-based media and wireless networking.

17. Twisted-pair cabling Has been around for a long time
Created for voice transmissions
Most widely used media for networking
Lighter
More flexible
Easier to install
Cheaper
Greater speeds
Two types:
Unshielded twisted pair (UTP)
Shielded twisted pair (STP)

18. Twisted-pair cabling UTP is more commonplace STP
provides the extra shielding by using an insulating material wrapped around the wire
Greater resistance to EMI and attenuation
More cost

19. Five main categories Category Cable Types Application 1 UTP
Analog voice 2
Digital voice, 1Mbps data 3
UTP, STP
16Mbps data 4
20Mbps data
5, 5e
Data, 100Mbps, 1G
6, 6e
Data, 1G, 10G

20. RJ-45 connectors RJ-45 are used with twisted-pair cabling.
Resemble ordinary phone jacks (RJ-11)
Eight wires instead of four
Larger.
Check out this page for how to make cat5 cable.
Cat6

21. Fiber-optic cable Use light transmissions
EMI, crosstalk and attenuation become no issue.
Well suited for data, video and voice transmissions
Most secure of all cable media
Installation and maintenance procedures require skills
Cost of cable
Cost of retrofitting of existing network equipment because incompatible with most electronic network equipment

22. Fiber-optic cable Single mode fiber: Multimode fiber:
A single direct bean of light, allowing for greater distances and increased transfer speeds.
Multimode fiber:
Many beams of light travel through the cable
This strategy weakens the signal, reducing the length and speed the data signal can travel.

23. Fiber-optic connectors
There are a variety of connectors and several ways of
Connecting these connectors, such bayonet, snap-lock,
and push-pull connectors. A couple here: FC
MIC, Standard FDDI
connector ST LC
SC duplex SC

24. Wireless media Three types:
Radio wave
Infrared
Microwave
Speeds of wireless solutions don’t keep pace with cable solutions
Installation and maintenance are far more complicated and costly.
Some solutions require line-of-sight, such as infrared and microwave.

25. IEEE standards
IEEE standards defines a range of networking systems that are bases on the original Ethernet standard.
Standard
Cable type
Segment Length
Connector
Topology
10Base2
Thin Coaxial
185 meters
BNC
Physical bus
10Base5
Thick Coaxial
500 meters
Vampire Taps
10BaseT
Category 3,4,5 twisted pair
100 meters
RJ-45
Physical star

26. Fast Ethernet IEEE 802.3u Standard Cable Type Segment Length Connector
Topology
100BaseTx
Category 5 UTP
100 meters
RJ-45
Physical star
100BaseT4
Category 3,4,5 UTP
100BaseFX
Multimode/Single-mode fiber-optic cable
412/Multimode fiber-optic 10,000/single-mode fiber-optic
SC,ST,MIC

27. Gigabit Ethernet 802.3z and 802.3ab
Standard
Cable Type
Segment length
Connector
1000BaseLX
Multimode/ single-mode fiber
550/multimode
5000/single-mode
Fiber connectors
1000BaseSX
Multimode fiber
550 meters using 50 Micron multimode fiber
1000BaseCX
STP twisted pair
25 meters
9-pin shielded connector, 8-pin fiber channel type 2 connector
1000BaseT
Category 5 UTP
100 meters
RJ-45

28. Check out this page for how to make cat5 cable. http://www. tomax7
Color codes
In the world of structured cabling systems the cryptic number 568 refers to the order in which the individual wires inside a CAT 5 cable are terminated. The termination could come at either the user’s end socket, the patch panel or termination frame or even the individual leads that connect a computer to the wall socket. There are currently two different specifications with respect to the order these cables should be terminated contained in the international standards document (ISO/IEC 11801:1995) as previously mentioned there is no indication as to which of these standards is preferred.

29. Pin Number Designations There are pin number designations for each color in T568B The pin designations are as follows: Color Codes for T568B Pin color pair name wh/or 2 TxData + 2 or 2 TxData – 3 wh/grn 3 RecvData+ 4 blu 1 5 wh/blu 1 6 grn 3 RecvData- 7 wh/brn 4 8 brn 4

30. The pinouts for a crossover cable
Straight-through
Crossover cable

31. Networking Devices repeaters Hubs Switches Bridges Routes Gateways
Network Interface Cards (NICs)
Wireless access points
Modems
Punch_down panels
Slelecting devices:

32. Hubs The bottom of the networking food chain
Connect device and create larger networks
Small hubs 5-8 ports (workgroup hubs)
Some hubs have more ports, up to 32 normally
Direct data packets to all devices connected to the hub - shared bandwidth
animation
Scalability, Collision, inefficient

33. Bridges Divide larger networks into smaller sections
Check MAC address, forward or block the data
Learning bridge builds list of MAC address by watching the traffic on the network.
Two issues to consider:
Placement 80/20 rule
Bridging loops
IEEE 802.1d Spanning tree protocol
Types of bridges
Transparent bridge
Source route bridge
Translational bridge
Transparent bridge: forward or block based on MAC
Source route bridge: Used in Token ring network. The entire path is embedded within the packet.
Translational bridge: convert one networking data format to another.

34. Bridges Source Route Bridge . Translational bridge
Used in Token Ring networks.
The entire path (ring number and bridge number) is embedded within Packet
Search frame
Route discovery frame
Translational bridge
Used to convert one networking data format to another.
For example, from Token Ring to Ethernet and vice versa. .

35. Switches Like hub, connectivity points of Ethernet network
Forward only to the port that connects to the destination device
knows MAC address
Match the MAC address in the data it receives.
Fully switched network, a dedicated segment for each device is connected to switch. Expensive.

36. Switches Allow full duplex Ethernet
Nodes only communicate with switch, never directly to each other
Use twisted pair or fiber optic cabling, using separate conductors for sending and receiving data.
collision pair is used to transmit data
It was half duplex before – one device can transmit at one given time,
double the capacity, 100Mbps become 200Mbps
Most LAN are mixed with hubs and switches.

38. Switch routing method
Packet-based switches use one of the following method to route packet.
Cut-through
Forward as soon as it received the destination MAC – first 14 bytes
Can cause propagation of error
Store-and-forward
Error checked before being forwarded
Errors are not propagated through network
Bad frames are discarded
Error checking takes time.
Considerably slower

39. Switch Routing Method FragmentFree Take the advantage of both.
Check errors by reading the first 64byte of packets where collision most likely happens
Offer near cut-through switching performance

40. Switch physical design
LAN switches vary in their physical design
Shared-memory
Common buffer for all ports
Matrix
Internal grid with input port and output crossing each other
First check MAC, then switch makes a connection where two ports (input/output) intersect
Bus-architecture
Common-bus
Dedicated buffer for each port and a circuit to control the bus access
CASE: buffer overflow
Our switch has a 2G buffer, it connected to all servers, including backup servers.
Every night, about 2TB data being backed up. Network was too busy.

41. Switch and Transparent Bridging
Most LAN switches use transparent bridging to create address lookup tables
Transparent bridging is a technology that allows a switch to learn everything it needs to know about the location of nodes on the network within the network administrator having to do anything. Has five parts:
Learning
Flooding
Filtering
Forwarding
Aging

44. Hub and switch cabling
To create larger networks, connect hubs and switches using
Standard port with special cable
Special ports with a standard cable
Standard port - Medium Dependent Interface-Crossed (MDI-X)
Two wires are crossed internally
Medium Dependent Interface (MDI)
To see each other as an extension, no signal to be crossed
Using crossover cable between two MDI-X ports
To uncross the internal crossing

45. Punch_down panels Wiring closets Labeling schemes
tch?v=3wdDRtGLiow
Labeling schemes
How to make cat5e cable :
How to make wire RJ45

46. Routers Create larger networks by joining two networks segments.
Dedicated hardware device or computer systems with more than one network interface and routing software.
Routing table
Static routing
Dynamic routing
Use special routing protocols to pass info to other routers.
Distance Vector Routing (RIP)
Link state routing (OSPF)

47. Switch and Router Different with router
Typically switch works on lower level (Data link Layer) while Router works in higher level (Network Layer)
Algorithms for router and switch about how to forward packers are different
For example, switch will forward broadcast, so does hub, not router- the address has to be specific.

48. Routers and Layer 3 Switch
While most switches operate at the Data link layer(layer2), some incorporate features of a router and operate at the network layer (layer3).
Layer 3 switches are faster because they are build on “switching” hardware
a router is needed for VLANS communication
Why not build a router in the switch itself and do the forwarding in hardware
EX: IP forwarding – all in hardware
Route lookup
Decrement the Time to Live (TTL)
Recalculation the checksum
Forward the frame the frame to correct output port
Can layer 3 switch replace router?
No. Layer 3 is good for workgroup and the backbone within an enterprise. But most likely will not replace the router at the edge of the WAN. Routers perform numerous other functions like filtering with access lists, BGP, and so on.

50. Gateways
Any device that translate one data format to another is called a gateway.
Router
Bridge
Software
Gateway and default gateway

51. CSU/DSU
Channel Server Unit/Digital Service Unit ( CSU/DSU) or Data Service Unit
Convert digital format on LAN into signal used on WAN
Sit between LAN and access point provided by telecom company
Many routers have CSU/DSU functionality

52. Wireless access points
Devices that provide connectivity between wireless LAN devices and in most cases a wired network.
Antennae
Convert signal from radio wave or other to that used on the LANs.
Small wlan can function without access point in so-called “ad hoc” or peer to peer mode,. Access points support “infrastructure” mode, which bridges with a wired Ethernet land and also scales the network to support more clients.

53. Modems
Modulator/Demodulator, convert digital signal generated by computer into analog signals that can travel over conventional phone line.
Connect to ISP
Dialing up to a LAN
Internal add-in expansion cards or external devices connect to serial or USB port
PCMCIA cards for laptop
Speed
Modem itself
Speed of the Universal Asynchronous Receiver/Transmitter (UART) chip,
UART has the speed of 921,600kbp

54. Network cards Called Network Interface Cards (NIC)
Attached to external port
PC card
Internal Network card
System bus compatibility
Peripheral Component Interconnect (PCI)
Industry Standard Architecture (ISA)
System Resources – device conflict
Media compatibility
Twisted pair, coaxial or fiber-optic connection?
Driver

55. ISDN adapters
Integrated Services Digital Networking (ISDN) is a remote access and WAN technology that can be used in place of a Plain old telephone systems dial-up link
Greater speeds than modem, pick up and drop the line considerable faster.
Require ISDN terminal adapter
Although digital signal, different format with the those used on LAN.
Create multiple communication channels on a single line.

56. System area network cards
Connecting computer systems in a cluster
High-performance unit.

57. Device
Function/Purpose
Key Points
Hub
Connects devices on a twisted-pair network.
A hub does not perform any tasks besides signal regeneration.
Switch
A switch forwards data to its destination by using the MAC address embedded in each packet.
Bridge
Divides networks to reduce overall network traffic.
A bridge allows or prevents data from passing through it by reading the MAC address.
Router
Connects networks together.
A router uses the software-configured network address to make forwarding decisions.
Gateway
Translates from one data format to another.
Gateways can be hardware or software based. Any device that translates data formats is called a gateway.
CSU/DSU
Translates digital signals used on a LAN to those used on a WAN.
CSU/DSU functionality is sometimes incorporated into other devices, such as a router with a WAN connection.
Network card
Enables systems to connect to the network.
Network interfaces can be add-in expansion cards, PCMCIA cards, or built-in interfaces.
ISDN terminal adapter
Connects devices to ISDN lines.
ISDN is a digital WAN technology often used in place of slower modem links. ISDN terminal adapters are required to reformat the data format for transmission on ISDN links.
System area network card
Used in server clusters to provide connectivity between nodes.
System area network cards are high-performance devices capable of coping with the demands of clustering applications.
WAP
Provides network capabilities to wireless network devices.
A WAP is often used to connect to a wired network, thereby acting as a link between wired and wireless portions of the network.
Modem
Provides serial communication capabilities across phone lines.
Modems modulate the digital signal into analog at the sending end and perform the reverse function at the receiving end.

58. MAC addresses
Unique 6-byte address burned info network interface, expressed in hexadecimal
No matter which protocol is used, MAC address is the means by which the network interface is identified on the network.
IEEE managing MAC address assignment
IEEE has a system Identifying the manufacturer by looking at the MAC address
Discover MAC address, depend on the OS
Ifconfig /all on WINDOWs NT/2000
Ifconfig –a on Linux/UNIX

59. Watch the Intel Gigabit demo.
gabit/base.swf
IP: GRE tunnels over IP
Generic Routing Encapsulation to encapsulate datagram in an IPv4 tunnel.

60. IEEE and Networking standards
Institute of Electrical and Electronic Engineers (IEEE) developed a series of networking standards
Networking technologies developed by manufacturers are Compatible
Cabling, networking devices and protocols are all interchangeable under the banner of a specific IEEE

61. Specification Name 802.1 Internetworking 802.2
The LLC(Logincal Link Control) sublayer
802.3
CSMA/CD ( Carrier Sense Multiple Access with Collision Detection) for Ethernet networks
802.4
A token passing bus
802.5
Token Ring networks
802.6
Metropolitan Area Network (MAN)
802.7
Broadband Technical Advisory Group
802.8
Fiber-Optic Technical Advisory Group
802.9
Integrated Voice and Data Networks
802.10
Standards for Interoperable LAN/MAN Security (SILS) (Network Security)
802.11
Wireless networks
802.12
100Mbps technologies, including 100BASEVG-AnyLAN
Each of these IEEE specifications outlines specific characteristics for LAN networking including the speed, topology, cabling and access method.

62. 802.3 IEEE standard Defines characteristics for Ethernet networks.
New additions, 802.3u for Fast Ethernet, 802.3z for Gigabit Ethernet, referred to as 802.3x.
Speed: Original 10Mbps, Fast Ethernet 100Mbps, Gigabit Ethernet 1000Mbps
Topology: bus or star.
Media: Coaxial and twisted pair cabling, also fiber optic cable.
Access method: CSMA/CD
Ethernet is by far the most widely implemented form of local area networking.

63. 802.5 IEEE standard
Specifies the characteristics for Token Ring Networks.
Introduced by IBM in the mid 80s, network topology of choice until the rise of the popularity of Ethernet.
Speed: 4 to 16Mbps
Topology: logical ring and most often a physical star. Logical ring is often created in the Multistation Access Unit (MSAU)
Media: twisted pair cabling.
Access method: token passing.
When a computer has data to send, it must use a special type of packet known as token. The token travels around the network looking for computers with data to send. The computer’s data is passed along with the token until it gets to the destination computer. At which point the data is removed from the token and the empty token placed back on the ring.

64. 802.11b IEEE Standard
Specifies the characteristics of wireless LAN Ethernet networks.
Special devices called wireless access points to allow communicate.
Also connect to wired networks to create wireless portions of entire networks.
Speed: b specifies 11M. Today g can be 108Mbps
Media: b standard is 2.4G radio waves.
Topology: physical wireless, logical bus
Access method: Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA ), a variation of CSMA/CD.

65. FDDI
Fiber Distributed Data Interface (FDDI) standard was developed by American National Standards Institute (ANSI)
Dual ring technology for fault tolerance
Speed: 100Mbps or higher
Topology: dual ring topology
Media: fiber optic cable, > 2 kilometers. Also possible use copper wire as Copper Distributed Data Interface (CDDI).
Access method: token-passing access method

66. Standard
Speed
Physical Topology
Logical Topology
Media
Access Method
802.3
10Mbps
Bus and Star
Coaxial and Twisted pair
CSMA/CD
(802.3u)
100Mbps( Fast Ethernet)
Star
Bus
Twisted pair
(802.3z)
1000Mbps
802.5
4Mbps and 16Mbps
Ring
Token passing
802.11b
11Mbps
Wireless
Radio waves
CSMA/CA
FDDI
100Mbps
Dual Ring
Fiber-optic Twisted pair/CDDI