Network Design
Yiannos Mylonas
Physical Topologies
There are two parts to the topology definition: the physical topology, which is the actual layout of the wire (media), and the logical topology, which defines how data flows through the network. Media
• Cable length • Cost • Ease of installation Copper Media
UTP (Unshielded Twisted Pair)
STP (Shielded twisted Pair)
UTP vs. STP
UTP
STP
• Does not include shielding around its conductors. Typically contains four pairs of stranded or solid conductors. Inexpensive and reliable. Supports distances of up to 100 meters. Supports data transfer rates up to 1Gbps.
• Includes shielding, typically a foil wrapper, around its conductors to improve the cable’s resistance to interference and noise. Typically contains four pairs of stranded or solid conductors. Supports up to 100 meters. More expensive than UTP.
UTP Categories
Category
Network Type and Maximum speed
1
Voice grade; not suitable for networking.
2
Digital telephone and low‐speed networks. Maximum speed:4
Mbps
3
Ethernet. Maximum speed: 10 Mbps with possible bandwidth of 16MHz. CAT 3 is currently used for telephone wiring.
4
IBM Token Ring. Maximum speed: 16 Mbps; may also be used for 10 Mbps Ethernet.
5 & 5e
Category 5: Fast Ethernet. Supports a signaling rate of 100Mbps.
Category 5e: Gigabit Ethernet. Supports a signaling rate of 350Mbps.
6
Gigabit Ethernet. Maximum speed: 1 Gbps. Supports a signaling rate of 250 MHz.
7
Gigabit Ethernet. Maximum speed: 1 Gbps+. Supports a signaling rate of 1 GHz.
Coaxial Connectors
Twisted Pair Connectors
RJ‐45 jack Front View
Fiber Optic
Fiber Optic Cable Mode Types
Mode Type
Description
Single‐mode fiber
Carries a single optical signal. Has a small core, which allows only a single beam of light to pass. A laser, usually operating in the infrared portion of the spectrum, is modulated in amplitude to transmit the signal though the fiber.
Step‐index multimode fiber
Contains a core surrounded by cladding, each with its own uniform index of refraction. When light from the core enters the cladding, a step down occurs due to the difference in the refractive indices. Step‐index fiber uses total internal reflection to trap light.
Graded index multimode fiber
Possesses variations in the core glass to compensate for the mode path length difference. Provided up to 2 GHz of bandwidth, which is significantly more than step‐index fiber.
Fiber connectors
Cable Type Properties
Cable Type
Properties
Coaxial
Transmission speed: 10 Mbps
Distance: Star topology, 6000 meters. Bus topology 3000 meters.
Duplex: Supports both half‐duplex and full‐duplex transmissions.
Noise Immunity: High
Frequency: 1GHz to 10 GHz
Fiber Optic
Transmission speed: 40000 Mbps
Distance: Multimode fiber is typically used for shorter runs of up to about 500 meters, and single‐mode for longer runs. The ultra high‐quality of some fiber cables allows runs of 100 km or more between repeaters.
Duplex: Consist of two fibers found in a side‐by‐side zip cord used for simultaneous, bi‐directional data transfer.
Noise Immunity: Superior
Frequency: Very High
Twisted Pair
Transmission speed:
•CAT 3: UTP at 10 Mbps
•CAT 5: up to 100 Mbps
•CAT 6: up to 155 Mbps
Distance: 540 meters
Duplex: full Capacity
Noise Immunity: 30 MHz
Frequency: Up to 600 MHz.
Repeater
HUBs
A hub is a networking device used to connect the nodes in a physical star topology network into a logical bus
topology. Two common types of hubs are passive and active. A passive hub simply receives data transmitted
from a device to one port and broadcasts it out to the devices connected on all other ports. An active hub
performs the same receive then broadcast action as a passive hub, and also regenerates or boosts the signal
much like a repeater. Hubs are generally inexpensive and easy to manage; however, they have a high degree of
contention due to all ports being in the same contention domain and therefore do not provide the best
performance in high‐traffic or latency‐sensitive situations.
Switch
•A switch is a networking device used to connect the drops in a physical star topology network into a logical bus topology. •Switches work with pairs of ports, connecting two segments into an isolated contention domain as needed. Most switches can work with multiple pairs of ports simultaneously to improve performance. While the exact mechanisms switches use to perform their duty varies, the ultimate purpose of a switch is always to transport data from point A to point B in the fastest manner possible.
Bridge
•Reduce Traffic
•Improves Performance
A bridge is a network device that divides a logical bus network into segments. Bridges examine the MAC address of each packet. If the packet is destined for a node connected to a different port, the bridge forwards the packet. If the packet is addressed to a node on its own segment, the bridge does not forward the packet. This arrangement reduces traffic between segments and improves overall network performance.
Router
A router is a networking
device that connects multiple
networks that use the same
protocol. Routers send data
between
networks
by
examining
the
network
addresses contained in the
packets they process.
Gateway Server
A gateway is a device, software, or a system that converts data between incompatible systems. Gateways can translate data between different operating systems, between different email formats, or between totally different networks.
Structure Cabling
The Telecommunications Industry Association (TIA) and the Electronic Industries Association (EIA) developed the 568 Commercial Building Telecommunication Cabling standard. This standard defines the regulations on designing, building, and managing a cabling system that utilizes structured cabling according to specified performance characteristics to create a system of unified communications.
Wiring Distributions Components
Subsystem
Description
Entrance facilities
Contains the telecommunication service entrance to the building. The demarcation point is usually 12 inches.
Backbone wiring
Provides connections between equipment rooms and telecommunication closets.
Equipment room
Provides the main‐connection point for an entire facility. Telecommunication closet
Houses the connection equipment for cross‐connection to an equipment room along with workstations in the surrounding area. It contains horizontal wiring connections, and entrance facility connections.
Horizontal wiring
Runs from each workstation outlet to the telecommunication closet. The maximum allowed distance from the outlet to the closet is 295 feet.
• Four pair 100 ohm UTP cable
•Two fiber 62.5/125‐mm fiber optic cable
•Multimode 50/125 mm multimode fiber optic cable.
Work area
Consists of wallboxes and faceplates, connectors, and wiring used to connect work area equipment to the telecommunication closet.
Premise Wiring
TIA/EIA 568‐A Horizontal Cabling Component
Horizontal Cabling System Structure
Horizontal Cabling System Structure
Horizontal Cabling System Structure
Premise Wiring Components
Premise Wiring Component
Description
Drop Cable
The wire that runs to a PC, printer, or other device to the network.
Patch panel
A connection point for drop and patch cables. Typically, a patch panel has one or more rows of RJ45 or other connectors. Drop cables are connected to the connectors. Patch cable
A cable that is plugged into the patch panel to connect two drops. A patch cable might or might not be a crossover cable, one in which the transmit conductor at one end is connected to the receive conductor at the other.
Cross connects
Individual wires that connect two drops at a patch panel. Cross connects are rarely used in modern networks.
Main distribution Frame (MDF)
A cable rack that interconnects the telecommunication wiring between itself and any number of IDFs.
Intermediate distribution frame (IDF)
A cable rack that interconnects the telecommunication wiring between an MDF and any workstation devices.
Wiring closet
A small room in which patch panels are installed. Drop cables radiate out from the wiring closet to the components on the network.
Patch Panel
Wiring Crimpers
Punch Down Blocks
A punch down block can be used to connect one group of telephone and network wires
with another group in utility or telecommunication closets. They typically support low‐
bandwidth Ethernet and token‐ring networks.
Demarc Point
Sizing for Wiring Closets
Wiring Closets
Wiring Closets
Star Topology
Star Topology
Ethernet Star Topology
Network Topology
Floor Plan
Multi‐Story Building
Multi‐Building Campus
Network Documentation
• Network diagrams
• Device Information
– Configuration for each device and list of all devices.
• Utilization statistics
– Measure network performance
• Policies and Procedures
Physical Network diagram
Logical Network Diagram
The logical network diagram documents the protocols and applications that control the flow of network traffic from one device to another. Items illustrated on a logical network diagram often include:
•The IP addresses of each network device.
•The FQDN of a device.
•The application type of each server (for example, mail server, file server, and so on).
•Any trust relationships that exist between nodes.
•The routing topology.
Plan for Disaster Recovery
Network live
Network recovery
Network failures
Disaster Categories
• Natural Disaster
– Fires, floods
• Data destruction
– Data loss: virus attack, accidental deletion, natural disaster
• Equipment Failure
– Hardware failure
Disaster Recovery plan
•
A disaster recovery plan is a policy and set of procedures that document how people and resources will be protected in case of disaster, and how the organization will recover from the disaster and restore normal functioning. The plan should be developed and implemented cooperatively among and between different functional groups.
Disaster Recovery Plan
The Network Reconstruction Plan
The Network Reconstruction Plan
The Network Reconstruction Plan
Hot, Warm, and Cold Sites
Maintain the Plan
Fault Tolerance Methods
Uninterruptible Power Supplies (UPS)
Partitions
Redundant Array of Independent disks (RAID) RAID Level 0
RAID Level 1
Mirroring
Duplexing
RAID Level 5
Link redundancy
Enterprise Fault tolerance
Enterprise Fault Tolerance