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NETWORKING HARDWARE (NETWORKING
DEVICES)
OBJECTIVES Identify major hardware devices in a computer
network Describe the factors involved in choosing a
network adapter, hub, switch, or router Describe the functions of repeaters, hubs,
bridges, switches, and gateways Identify problems associated with connectivity
hardware
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NETWORKING DEVICES Device: Equipment that connects directly to a network
segment.End user devices or hosts
Hosts are devices that connect directly to a network segment. It includes: Computers (Client / Servers), Printers, Scanners, etc.
Network Devices:Include all devices that connect the end-user devices to
allow them communicate.
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NETWORK ADAPTERS Also called network interface cards (NICs) Connectivity devices enabling a workstation, server,
printer, or other node to receive and transmit data over the network media
In most modern network devices, network adapters contain the data transceiver.
The NIC controls the host’s access to the medium. Translates parallel signals produced by the computer
into serial format that is sent over the network. The MAC address is hard coded onto the NIC.
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NETWORK INTERFACE CARD - NIC Transceiver:
Send and receive signalsConvert one type of signal (or connector)
into another. Internal and / or External Layer 1 device. It looks only at bits and not
at any address information or higher level protocols
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NETWORK INTERFACE CARD
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FROM PARALLEL TO SERIAL, AND VICE VERSA
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SELECTING A NETWORK CARD Consider the following factors
Network Architecture or LAN Technology: Ethernet, Token Ring, FDDI, etc.
Type of Media: Thinnet or 10Base2, Thicknet or 10Base5, 10BaseT, Fiber Optic)
Data Transfer SpeedType of System Bus:
ISA, EISA, Microchanel, PCI, PCIMCA)Some NICs connect through SCSI busSome NICs use USB Integrated on the Motherboard
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AN ETHERNET NIC
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TYPES OF NETWORK ADAPTERS
PCMIADeveloped in early 1990s to provide standard interface for
connecting any type of device to a portable computerMore commonly known as PC Cards
USB (universal serial bus) portStandard external bus that can be used to connect multiple
types of peripherals A parallel port network adapter Wireless network adapters A variety of Ethernet network adapters
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TYPES OF NETWORK ADAPTERS
PCMIADeveloped in early 1990s to provide standard interface for
connecting any type of device to a portable computerMore commonly known as PC Cards
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TYPES OF NETWORK ADAPTERS
USB (universal serial bus) portStandard external
bus that can be used to connect multiple types of peripherals
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TYPES OF NETWORK ADAPTERS
A parallel port network adapter 13
TYPES OF NETWORK ADAPTERS
Wireless network adapters
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TYPES OF NETWORK ADAPTERS
Ethernet network adapters for printers
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NETWORK DEVICES
Provide transport for the data that needs to be transferred between end-user devices.
Extend cable connections Concentrate connections Convert Data Formats Manage data transfer
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CONNECTIVITY DEVICES Each topology and network architecture has its
limits. Beyond a point networks networks can not be
expanded by simple adding more servers or cabling
Connectivity devices are the basic building blocks of network expansion
Are used to connect separate segments of the network or inter-network
A segment is a portion of the network transmission media that is assigned a network address.
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CREATING LARGER NETWORKS
Physically expand the network
Segment network to filter traffic
Extend network to connect separate LANs
Connect two separate computer environments
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DEVICES TO EXPAND NETWORKS
Repeaters BridgesSwitchesRoutersGateway
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INTERNETWORK CONNECTIVITY DEVICES
Routers Gateways
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A repeater can be used to increase the length of your network by eliminating the effect of attenuation on the signal.
A repeater contains one input port and one output port, so it is capable only of receiving and repeating a data stream.
It connects two segments of the same network, overcoming the distance limitations of the transmission media.
Repeaters are suited only to bus topology. Some repeaters also serve as transmission media adapters,
connecting two different types of media.
REPEATERS
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Repeaters repeat signalsClean and boost digital transmissionAnalog networks use amplifiers to boost signal
Repeaters only work with the physical signalCannot reformat, resize, or manipulate the data
Physical layer (layer 1) device.
REPEATERS
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REPEATERS
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REPEATERS
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A hub is referred as a concentrator or a multiport repeater containing multiple ports to interconnect multiple devices
A hub accepts signals from a transmitting node and repeats those signals to all other connected nodes in a broadcast fashion.
All devices connected to a hub share the same amount of bandwidth and the same collision domain.
Regenerate and repeat signals Propagate signals through the network Can not filter network traffic Can not determine the best path 25
HUB
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HUB
ADVANTAGES AND DISADVANTAGES OF REPEATERS AND HUBS Advantages of using repeaters
Extend network physical distanceDo not seriously affect network performanceSpecial repeaters connect different media
Copper to fiber Disadvantages of using repeaters
Cannot connect different network architecturesToken Ring and Ethernet
Cannot reduce network traffic27
Disadvantages of using repeaters Do not segment the network
Repeat everything without discriminationNumber of repeaters must be limited
Repeaters are part of a collision domain
ADVANTAGES AND DISADVANTAGES OF REPEATERS AND HUBS
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Layer 2 (Data Link Layer) device.Divide a network into segments and filter traffic. Each segment is a collision domain.Limit or filter traffic keeping local traffic local yet allow connectivity to other parts (segments)Forward or drop framesCannot filter broadcastsMAC to segment # tableMAC to segment # table initial developmentMake decision based on the MAC address listConnect different architectures and Forward packets between architectures: Ethernet & Token-Ring.
BRIDGES
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Addresses are 6 bytes long Generally written in hexadecimal Globally unique (unicast)
00.0C.12.34.AB.CD - legal FF.FF.FF.FF.FF.FF - legal 00.00.01.10.45.G2 - illegal
To ensure a unique MAC address, the Ethernet card manufacturers encode the MAC address onto the card, usually in a ROM chip. The first half of the address identifies the manufacturer of the card. This code, which is assigned to each manufacturer by the IEEE, is called the organizationally unique identifier (OUI). Each manufacturer assigns a MAC address with its own OUI as the first half of the address, with the second half of the address being assigned a number that this manufacturer has never used on another card
MAC ADDRESS
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BRIDGES
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Creating a Forwarding Table• Based on the addresses of the sending computers• New addresses are added if they are not in the table
Add01
Add03
Add02
S 01 D 02
Forwarding tableSeg 1 Seg 2
01
02Stop
S 02 D 01
BRIDGES
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BRIDGES
Transparent bridges are also called learning bridges. Build a table of MAC addresses as frames arrive Ethernet networks use transparent bridges. Token Ring networks use source-routing bridges. Translation bridges Connect networks with different
network architecture, example: Token ring connecting to Ethernet.
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BRIDGES
ADVANTAGES AND DISADVANTAGES OF BRIDGES
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Subdivide a network into smaller logical pieces. Switches operate at the Data Link layer (layer 2) of the OSI
model. Can interpret address information. Switches resemble bridges and can be considered as a high
speed multiport bridge. Replacing repeaters & hubs in UTP Switches maintain a switching table. Dedicated bandwidth to each port, making data transmission
more efficient. Each port can use full 10/100/1000 Mbps. 36
SWITCHES
As a multiport device, it can better use limited bandwidth and prove more cost-effective than bridge.
Switches divide a network into several isolated channels. Packets sending from 1 channel will not go to another if
not specified. Each channel has its own capacity and need not be shared
with other channels. Switch is combination
of hub and bridge.
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SWITCHES
Switch is combination of hub and bridge. Workstations that connect to hub are on shared segment. Workstations that connect to switch are on switched
segment.
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SWITCHES
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SWITCHES
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SWITCHES
Full duplex switch allows for simultaneous transmission and reception of data to and from workstation.
Full duplex connection helps to eliminate collisions. To support full duplex connection to switch, two sets
of wires are necessary - one for receive operation and one for transmit operation.
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SWITCHES
TYPES OF SWITCHES – CUT THROUGH SWITCH
Read only address information in MAC layer head before beginning processing.
After reading destination address, switch consults an address look up table to determine which port on switch this frame should be forwarded to.
Once address look up is completed, point-to-point connection is created and frame is immediately forwarded.
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Preamble Des. Add Sour. Add Length Data FCS
7 Bytes
2/6 Bytes
2/6 Bytes
2 Bytes
46 - 1500 Bytes 4 Bytes
1 Byte
TYPES OF SWITCHES- STORE AND FORWARD
Store and Forward switches – read entire frame into shared memory area in switch.
Contents of transmitted Frame Check Sequence (FCS) field is read and compared to locally recalculated frame check sequence.
If results match, switch consults address look up table, builds appropriate point-to-point connection, and forwards frame.
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TYPES OF SWITCHES- ERROR FREE CUT THROUGH
SWITCHES Error free cut through switches – read both addresses
and frame check sequences for every frame. Frames are forwarded immediately to destination nodes
in an identical fashion to cut through switches. Should bad frames be forwarded, error free cut through
switch is able to reconfigure those individual ports producing bad frames to use store and forward switching.
As errors diminish to preset thresholds, port is set back to cut through switching for higher performance throughput.
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USING SWITCHES TO CREATE VLANS
Virtual local area networks (VLANs)Network within a network that is logically defined by
grouping its devices’ switch ports in the same broadcast domain.
Switches can logically group together some ports to form a virtual local area network (VLAN)
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Switches can be configured to communicate only within the devices in the group
HubHub
Hub
SW1
SW2
SW3
VLAN1 VLAN2
USING SWITCHES TO CREATE VLANS
HIGHER-LAYER SWITCHES
Switch capable of interpreting Layer 3 data is called a Layer 3 switch
Switch capable of interpreting Layer 4 data is called a Layer 4 switch
These higher-layer switches may also be called routing switches or application switches
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Advantages of switchesIncrease available network bandwidthReduced workload, computers only receive packets
intended for them specificallyIncrease network performanceSmaller collision domains
SWITCHES
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Disadvantages of switchesMore expensive than hubs and bridgesDifficult to trace network connectivity problems
through a switchDoes not filter broadcast traffic
SWITCHES
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SWITCHES
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ROUTERS
Multiport connectivity device Can integrate LANs and WANs running at different
transmission speeds and using a variety of protocols Routers operate at the Network layer (Layer 3) of the OSI
Model. Connect networks with multiple paths between network
segments (subnets) Make decisions based on the network address. Connect different layer 2 technologies (ethernet, Token
Ring, FDDI, etc.) Have become the backbone for the Internet, running the
IP protocol. 51
ROUTERS
Its purpose is to:examine incoming messages (layer 3 data), choose the best path for them through the network, and switch them to the proper outgoing port.
They don’t allow bad data or broadcast storm to be passed on the network.
They can connect networks using the same protocol but different network architecture.
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ROUTERS Calculates the optimal path to a particular network
Reroute packets if a path is not available Routing tables stored in the router list all known addresses
and possible paths. Consist of hardware and software
Hardware Network server, separate computer, special black box Physical interface for various networks
Software Operating system and Routing protocol
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ROUTER FEATURES AND FUNCTIONS
Filter out broadcast transmission to alleviate network congestion
Support simultaneous local and remote activity Provide high network fault tolerance through redundant
components. Monitor network traffic and report statistics to a MIB Diagnose internal or other connectivity problems and trigger
alarms. Routers often incorporate firewall functions. A router accepts an outgoing packet, removes any LAN
headers and trailers, and encapsulates the necessary WAN headers and trailers
Because a router has to make wide area network routing decisions, the router has to dig down into the network layer of the packet to retrieve the network destination address
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Static routingTechnique in which a network administrator programs a
router to use a specified paths between nodes Dynamic routing
Automatically calculates best path between nodes and accumulates this information in a routing table
HopTerm used in networking to describe each trip data take
from one connectivity device to another
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ROUTER FEATURES AND FUNCTIONS
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Static Routers Dynamic Routers
Manual configurationof routes
Manual configuration of the firstroute. Automatic discovery of newroutes
Always use the sameroute
Can select the best route
More secure Need manual configuration toimprove security
ROUTER FEATURES AND FUNCTIONS
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ROUTER FEATURES AND FUNCTIONS
ROUTING PROTOCOLS
To determine the best path, routers communicate with each other through routing protocols
In addition to its ability to find the best path, a routing protocol can be characterized according to its convergence time and bandwidth overheadConvergence time
The time it takes for a router to recognize a best path in the event of a change or outage
Bandwidth overheadBurden placed on an underlying network to support the
routing protocol58
ROUTING PROTOCOLS
The four most common routing protocols:RIP (Routing Information Protocol) for IP and IPXOSPF (Open Shortest Path First) for IPEIGRP (Enhanced Interior Gateway Routing Protocol)
for IP, IPX, and AppleTalkBGP (Border Gateway Protocol) for IP
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BROUTERS AND ROUTING SWITCHES
Bridge routerAlso called a brouterIndustry term used to describe routers that take on
some characteristics of bridges Routing switch
Router hybrid that combines a router and a switch.Another name to switch layer 3.
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PHYSICAL VERSUS LOGICAL ADDRESSES
MAC addressesData Link layer applicationUsed by switches, bridges, and routersUsed for directly connected devices
Logical addressesNetwork and transport protocols dictate the format of
the logical network layer addressTCP/IP, IPX/SPXIP addresses are assigned manually or by software
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ADVANTAGES AND DISADVANTAGES OF
ROUTERS
Advantages of routers Can connect networks of different architecture
Token Ring to Ethernet Choose best path through or to a network Create smaller collision domains Create smaller broadcast domains
Disadvantages of routers Only work with routable protocols More expensive than hubs, bridges, and switches Routing table updates consume bandwidth Increase latency due to a greater degree of packet
filtering and/or analyzing62
ROUTERS
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BROUTERS
Hybrid device Functions as a router for routable
protocols Functions as a bridge for non-routable
protocols Operates at Data Link and Network layers
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GATEWAYS
Combination of networking hardware and software that connects two dissimilar kinds of networks
Translate between different protocol suites Operates on all 7 layers of the OSI model Most negative on network performance
Latency Popular types of gateways include:
E-mail gatewaysIBM host gatewaysInternet gatewaysLAN gateways
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