Transcript LAN BASICS

CHAPTER
Network Hardware
Chapter Objectives
• Describe the important basic network
hardware and the internetworking
hardware
• Discuss the desired characteristics of a
server and a workstation
• Present different switching technologies
• Examine the routing process with the
help of an example
Introduction
Module 1
(4-06)
Network Hardware Categories
• Local networking hardware
• Internetworking hardware
Local Networking Hardware
• Network Interface Cards (NICs)
• Cables
• Connectors
• Line drivers or repeaters
• Hubs / Switches
• Servers
• Workstations
Internetworking Hardware
• Line drivers or repeaters
• Transceivers
• Bridges
• Switches
• Routers
• Gateways
Current Day Internetworking
Devices
• Mostly confined to the following:
– Switches
– Routers
Folding of Devices into Switches
• Show Diagram
Folding of Devices into routers
• Show Diagram
Manageable Devices
• Switches and routers in a large network
can be managed from a remote console
End of Module
MODULE
Network Interface Cards (NICs)
NIC Basics
• Technology used
• Connectors used
• Speed of the network
• Interface technologies
An Actual NIC Description
• 100BaseTX, PCI card
–
–
–
–
100 = speed in Mbps
Base =Ethernet
TX = Twisted pair
32-bit = bus width; it may also be 64-bit
wide
– PCI = bus technology
10BaseT NIC
• 10BaseT cards
–
–
–
–
–
Physical star and logical bus networks
10 Mbps speed
Ethernet standard
Twisted pair wiring
RJ-45 Connectors
10Base2 NIC
• 10base2 cards
–
–
–
–
–
Physical bus and logical bus networks
10 Mbps speed
Ethernet standard
Thin coaxial wiring
BNC connectors
10Base5 NICs
• 10Base5
–
–
–
–
–
Physical bus and logical star networks
10 Mbps speed
Ethernet standard
Thick coaxial wiring
AUI connectors are used
• Note: 10BaseT, 10Base2 and 10Base5 are
not used widely in practice anymore
100BaseTX NIC
• 100BaseTX
– 100 Mbps speed
– Fast Ethernet standard
– Twisted pair
• Higher quality Category 5 wires are normally
required to implement 100 mbps Ethernet
networks
1000BaseT NICs
• 1000BaseT
– 1000 Mbps
– Ethernet
– Twisted-pair wire
• Category 5e
• 1000BaseF
– 1000 Mbps
– Ethernet
– Optical fiber wire
1000BaseT NIC
Source: 3Com
Note the RJ-45 connection and the
status lights on the card
Gigabit Ethernet Fiber NIC
Source: 3Com
•Note the two connectors for
the RX and TX connections
•For use with PCI and PCI-X
servers
Gigabit Ethernet NIC Properties
(Source: 3Com)
• Tenfold throughput boost: accelerate Fast Ethernet
server connections to 1000 Mbps
• Fiber-optic cabling supports data security and faster
throughput
• Automatic link aggregation and fail-over allow
multiple NIC connections to be installed
• Advanced server features maximize availability,
scalability, and fault tolerance
Gigabit Ethernet NIC Properties
(Source: 3Com)
• 64-bit PCI and PCI-X support: faster transmissions
with lower CPU utilization
• Centralized, standards-compliant management
lowers network administration time and total cost of
ownership
• TCP/UDP/IP checksum offloads reduce host CPU
load for improved system performance
• PCI Hot-Plug lets you remove/replace server NICs
without taking the server offline
Token Ring Cards
• Token ring network cards
• Earlier token ring cards
– 4/1 Mbps
• Later token ring cards
– 16/4 Mbps
• Newer token ring cards
– Fast token ring networks
– 100/16/4 Mbps
PCI Bus Types for NICs
• Width
– Bus width is 32-bit or 64-bit
• Bus frequency
– 33 MHz
– 66 MHz
– 100 MHz etc.
• Technology
– PCI
– PCI-X
– PCI Express
Source: Tomshardware:
www6.tomshardware.com/howto/02q3/020904/diy-06.html
Cable Connections for NICs
• BNC barrel connector
– Thin coaxial
• RJ 45
– Twisted pair
• Note the difference between RJ 11 and RJ-45
– RJ-11 is smaller and it is used in telephone
connection
– RJ-45 is larger and it is used in LAN connections
Different Coax Connectors
Coaxial Cable Connectors
T connector
Thin coaxial
cable
Terminator
Network
Interface
Card
BNC
AUI and Combo Cable
Connections for NICs
• AUI Possibilities
– Designed for a thick coaxial cable
– Designed for a token ring network
• Combo Cards
– Consisting of different ports
– BNC, RJ-45, AUI
RJ-45 Connectors
RJ-45 Port
RJ-45 Connector
Possible Combo Card
Connections
• Thin coaxial cables (BNC)
• Twisted pair wires (RJ-45)
• Phone connection (RJ11)
• Thick coaxial cables (AUI)
Wireless Network Interface
Cards
• IEEE 802.11b
– 2.4 GHz, 11 Mbps
• IEEE 802.11b+, IEEE 802.11g?
– 2.4 GHz, up to 20% more throughput
• IEEE 802.11a
– 5.8 GHz, 54 Mbps
• IEEE 802.11g
• 2.4 GHz, 54 Mbps, 108 Mbps (Full duplex)?
• IEEE 802.11n
Example of Older 10Base2 Card
BNC
Source: Black Box
Example of Older 10BaseT Card
ISA
RJ 45
Source: Black Box
Example of Older Combo Card
RJ 45
Combo
Source: Black Box
BNC
D-Link Fast Ethernet Card
(100BaseTX)
D-Link 100BaseTX Specs
(Source D-Link)
• A manageable 10/100MB Dual Speed
Ethernet PCI Network Interface Card with
Wake-On-LAN (WOL)
• Fully compliant with IEEE802.3 10Base-T,
IEEE 802.3u 100Base-T specifications
• Supports ACPI/WOL (Advanced
Configuration Power Management Interface)
feature, IP Multicast packet filtering, PXE
(PreBoot execution Environment) Boot ROM,
IEEE 802.1p, IEEE 802.1Q, and DMI (Desktop
Management Interface).
A Note on Remote Wake on LAN
(Source: Intel)
• A remote wake-up technology that enables
you to remotely power systems "on" for offhours maintenance. A result of the Intel-IBM
Advanced Manageability Alliance and part of
the Wired for Management Baseline
Specification, this technology helps save time
on automated software installations,
upgrades, disk backups and virus scans.
Equally important, it increases end-user
productivity by moving such planned
disruptions to off-hours.
Fast Ethernet PC Multi-Port
Card
NIC and
modem connections
Fast Ethernet Card Specs.
The D-Link DMF-560TX is a 10/100Mb Dual Speed Ethernet PC Card with
an integrated V.90/K56flex Data/Fax Modem. The DMF-560TX is targeted
at notebook and laptop users that connect to a wide variety of datacommunications devices and services, and require access to faster
technologies. Laptop users are able to seamlessly connect to both Ethernet
and Fast Ethernet LANs, as well as send and receive faxes, connect to the
Internet, and dial into a Remote Access Server or PC using this one
PCMCIA PC Card solution.
The DMF-560TX strictly adheres to the IEEE Ethernet standards and the
ITU Data Communications and Modem standards in order to ensure
maximum interoperability. The DMF-560TX attempts to connect at the
highest speed supported by an ISP, LAN, host modem, or fax machine and
automatically defaults to a lower speed until a stable connection can be
created.
Fast Ethernet Card Operational
Specs.
Modem Operating Protocols
•V.90 (down-stream up to 56,000 bps)
•K56flex (down-stream up to 56,000 bps)
•V.34bis (up to 33,600 bps)
•V.34 (2,400 to 28,800 bps)
•V.32bis, V.32, V.22bis, V.23, V.22/Bell 212A, V.21/Bell 103
Error Correction Data Compression
•V.42/V.42bis and MCP Class 2 to 5
Fax Compatibility
•Group 3 send and receive
•EIA Class 1 fax commands
•V.17 (14,400 bps), V.29 (9600 bps), V.27ter (4800 bps),
•V.21 (300bps)
Token Ring Adapter (NIC)
Note the connector type.
Ethernet to Token Ring Bridge
Wireless PC Card Adapter
Wireless PC Card Specs
D-LinkAir DWL-650 PC Card Type-II
11Mbps Wireless LAN Adapter
The D-Link DWL-650 is an IEEE 802.11b compliant PC Card Type-II
11Mbps wireless LAN adapter. The DWL-650 will operate in 2.4 GHz
Direct Sequence Spread Spectrum (DSSS) for wireless networks in the
home or office environment. It is designed to operate in 3.3V or 5.0V DC
slots. In addition, the DWL-650 uses a 64/128-bit WEP (Wired Equivalent
Privacy) Encryption for a secure network connection.
The D-Link DWL-650 can operate in either Ad-Hoc mode (Peer-to-Peer
networking without access point) or Infrastructure mode (Peer-to-Peer
networking using an access point). In Infrastructure mode, the DWL-650
can be connected to a broadband residential gateway or a DSL/Cable
modem for high-speed wireless Internet access on the existing network.
Wireless PC Card Specs
The DWL-650 can transmit data at 11, 5.5, 2 or 1 Mbps per
channel. The DWL-650 transmit rate values can be manually
selected for Auto Select 1 or 2 Mbps, Fixed 1 Mbps, Fixed 11
Mbps, Fixed 2 Mbps, Fixed 5.5 Mbps and Fully Auto. The
DWL-650 has full mobility and seamless roaming from cell to
cell as well as across access points. The range of coverage per
cell for indoor use is up to 328 feet and up to 984 feet per cell
for outdoor use.
The DWL-650 comes with an internal non-detachable diversity
patch antenna and one built-in green LED indicator for power,
network link and activity. The DWL-650 is compatible with
Windows 98, Windows ME, Windows 2000, Windows XP.
Wireless PCI Card
Wireless PCI Card Specs
The D-LinkAir DWL-520 is an IEEE 802.11b wireless PCI
adapter. The DWL-520 provides an integrated PCI solution
that will operate within the 2.4 GHz Direct Sequence Spread
Spectrum (DSSS) for wireless networks in the home or office
environment. Along with the advanced wireless technology
that is incorporated into the DWL-520, wide range
motherboard support is assured by compliance to the latest
PCI 2.2 standard interface. The DWL-520 is the solution for
users and network administrators looking for the convenience
offered by a wireless connection.
Wireless PCI Card Specs Cont.
The D-Link DWL-520 can operate in either Ad-Hoc mode (Peer-toPeer networking without an access point) or Infrastructure
mode (Peer-to-Peer networking using an access point). In
Infrastructure mode, the DWL-520 can be connected to a
wireless residential gateway with a broadband connection to
enable wireless sharing of the High-speed Internet access.
The DWL-520 can transmit data at rates of 11Mpbs, 5.5Mbps, 2Mps
and 1 Mbps per channel. With its detachable antenna using a
reverse SMA connector, the DWL-520 has an effective range of
up to 230 feet for indoor use and up to 984 feet in an outdoor
environment. In addition, the DWL-520 supports 64/128-bit
WEP (Wired Equivalent Privacy) Encryption for network
security.
Wireless 5 GHz
Wireless 5 GHz Specs
•Next generation of wireless products with its highperformance D-LinkAir Pro series of 5GHz networking
technology.
Designed for indoor use, the D-LinkAir Pro DWL-A650 is a
powerful notebook PC CardBus adapter that allows users to
have mobile access to networks. It provides roaming
capabilities from cell to cell and network to network.
•At 54 Megabits per second (Mbps), the D-LinkAir Pro DWLA650 5GHz high speed wireless CardBus adapter delivers the
fastest standards-based wireless technology in the industry.
With IEEE 802.11a standard compliance, the D-LinkAir Pro
DWL-A650 high-speed wireless adapter provides excellent
network interoperability.
Wireless 5 GHz Specs
(Continued)
• A proprietary “Turbo” mode allows the D-LinkAir Pro DWLA650 to operate at significantly greater data rates up to 72Mpbs.
Eight non-overlapping channels create less interference, which
supplies higher average cell throughput to clients. The DLinkAir Pro DWL-A650 employs enhanced 152-bit Wired
Equivalent Privacy (WEP) and Dynamic Key Exchange to
protect data from unauthorized access.
• The D-LinkAir Pro DWL-A650 is easily installed into a laptop
PC to provide connectivity directly to another wireless enabled
device (ad-hoc mode) or through an 802.11a based access point
(infrastructure mode).
END OF MODULE
MODULE
NIC Resources
NIC Resources
• IRQ
• I/O address
• Base memory address, if provided
• DMA, if provided
IRQ
• Must be unique for each device, unless
it is steered
– IRQ steering
• An NIC requires an IRQ
• IRQ is used to gain the attention of the
CPU
• There are a limited number of IRQs
available on a computer
IRQ Assignment (learnthat.com)
IRQ
Device
0
Timer
1
Keyboard
2
Wired to IRQ 9
3
COM 2 (COM 4)
4
COM 1 (COM 3)
5
Available (often LPT2, sound cards, or network cards)
6
Floppy Disk Controller
7
LPT1
8
Clock
9
Wired to IRQ 2
10
Unused
11
Unused
12
Mouse Port
13
Coprocessor
14
Hard Disk Controller
15
Unused
I/O Address
• Must be unique to each device
• Each device of port must have an I/O
address
• The NIC must have an I/O Address as
well
Common I/O Address
Assginemnt (learnthat.com)
Address (Hex)
00-0F
20-21
40-43
1F0-1F8
200-20F
238-23B
278-27F
2E8-2EF
2F8-2FF
300-30F
330-33F
378-37F
3E8-3EF
3F0-3F7
3F8-3FF
Device
DMA Controller
Interrupt Controller
Timer
Hard Disk Controller
Joystick Controller
Bus Mouse
LPT2
COM4 Serial Port
COM2 Serial Port
Ethernet Card
MIDI Port
LPT1 Port
COM3 Serial Port
Floppy Disk Controller
COM1 Serial Port
I/O Address
(www.techencylopedia.com )
• There is a 64K address space for I/O
addresses, although typically less than 1K is
used. Each board that uses an I/O address
contains a few bytes of memory (16, 32, etc.)
set to a default address range. One or more
alternate addresses is also provided to
resolve conflicts with other boards. These I/O
spaces are a bunch of tiny memory banks
scattered over different devices. As long as
each one is set to a different address, the
CPU can transmit signals to the appropriate
boards without conflict.
I/O Address Continued
(www.techencylopedia.com )
• An I/O address operation takes place as
follows. If a program needs to send a byte to
the serial port, it issues an OUT instruction to
the CPU with the address of that serial port.
The CPU notifies the address bus to activate
the I/O space, not regular memory, and the
address bus signals the appropriate byte
location on the board. The CPU then sends
the data character over the data bus to that
memory location.
Base Memory Address
• Must have a unique range for the NIC
card
• Some older cards did not require the
base memory address to be specified
DMA
• Direct Memory Access
• Channels are assigned for DMA
• Not all the NIC cards have DMA
• Newer PCI technologies used for
expansion slots have made DMA
somewhat obsolete
DMA Use (Source
learnthat.com)
• In most PCs, there are 8 DMA Channels.
• In most modern PCs, DMA shouldn't be used
as it just slows it down. But, older PCs may
use DMA.
• Channels 4-7 are usually available, while
Channel 0 is used to refresh DRAM, Channel
1 is used by a hard disk controller or sound
card, and Channel 2 is usually used by the
floppy disk controller.
Resource Allocation on a NIC
Examining the Network
Resources
Device Manager
NIC
Resources
Properties
END OF MODULE
MODULE
Network Connectors and Hubs
Simple Connectors
• T connectors
– An interface between the NIC and the
cables
• Terminators
– Used at both ends of a bus network
T Connector
Terminator
Example of T-Connector and
Terminator
T Connector
Source: Black Box
Terminator
Connectors : Hubs
• Types
– Passive hub
– Active hub
– Intelligent hub
• Passive hubs
– Simply provides the physical and the electrical
connection for the network
• Active hubs
– A Multi-port device
– Amplifies LAN signals
• Manageable hubs
– Has built-in manageability
– Some are manageable hubs
Connectors : Passive Hub
MAU
WS
WS
Hub Connecting A Token-ring Network
WS
A Manageable Hub/ Switches
WS
Backbone
WS
WS
Remote
Workstation
Remote Monitor
Active Hub
LAN Management Software
• Sophisticated
• Monitor the network traffic through
each of the ports
• Becoming popular
• Standardized protocol for remote
management exists
– SNMP (Simple Network Management
Protocol)
SNMP
• A major protocol used in the
management of networks
• A number of LAN management
software is based on the SNMP protocol
SNMP Cont. (Source: Cisco)
• The Simple Network Management Protocol (SNMP) is an
application-layer protocol designed to facilitate the exchange of
management information between network devices.
• By using SNMP-transported data (such as packets per second
and network error rates), network administrators can more easily
manage network performance, find and solve network problems,
and plan for network growth.
• SNMP is a relatively simple protocol, yet its feature set is
sufficiently powerful to handle the difficult problems presented in
trying to manage today's heterogeneous networks.
• Today, SNMP is the most popular protocol for managing diverse
commercial internetworks as well as those used in universities
and research organizations.
SNMP Cont.
• Like the Transmission Control Protocol (TCP), SNMP
is an Internet protocol.
• There are two versions of SNMP: Version 1 and
Version 2.
•
Most of the changes introduced in Version 2
increase SNMP's security capabilities. Other changes
increase interoperability by more rigorously defining
the specifications for SNMP implementation.
• SNMP's creators believe that after a relatively brief
period of coexistence, SNMP Version 2 (SNMPv2)
will largely replace SNMP Version 1 (SNMPv1).
Web Research
• Obtain additional information on the
following LAN troubleshooting
software
– LAN Analyzer
– LAN Sniffer
Example of a Hub Used in Ring
Network
Source: Black Box
Example of Hubs Used in the
Star Network
Stackable
Hubs
Source: Black Box
END OF MODULE
Web Research
• Photonic switching
– www.agilent.com/comms/photonicswitch
– www.cnn.com/tech
MODULE
Server and Workstation
Hardware
Module Objectives
• Give an overview of the different types
of the server hardware
• Discuss the desired characteristics of a
server
• Provide a specification for a
workstation
Servers
• Types
– Powerful micros
– Servers
– Super-servers
– Mini and large computers are used as
servers
• In a client-server environment, the server
also acts as an engine for database execution
• In general, the server is used for the sharing
of stored data and application
Desired Characteristics of Server:
Processor and Storage
Requirement
• Powerful processor
– Latest Pentium Processor for example
– Multiple processors, if necessary
• Large storage space
– Several gigabytes at a minimum
– Actual requirement will vary with LAN size
• Fast disk access speed
– Less than 10 ms, for example
• Versatile CD-ROM access (Towers)
• Fault tolerance
Processors
•
•
•
•
Intel Pentium 4, 32-bit processors
Intel Itanium 64-bit processors
Special Xeon processors meant for servers
Multiple processors
– Symmetric Multi-Processing (SMP)
• Other processors
– Spark (Sun), AMD, Motorola, IBM’s own
processors etc.
Symmetric Multiprocessing
(SMP) Source: Search390.com
• SMP (symmetric multiprocessing) is the
processing of programs by multiple
processors that share a common operating
system and memory. In symmetric (or
"tightly coupled") multiprocessing, the
processors share memory and the I/O bus or
data path. A single copy of the operating
system is in charge of all the processors. SMP,
also known as a "shared everything" system,
does not usually exceed 16 processors.
Chip Set
• Chip sets designed for servers to boost
I/O operation
Hard Disk Technologies
• SCSI
• ATA
• Serial ATA (SATA)
• Fiber channel storage
• RAID
Overview of Storage
Technologies
• SCSI, Small Computer Systems Interface, is widely
used in mid- to high- performance workstations and
servers.
• SCSI offers faster transfer rates than ATA/IDE, the
interface most commonly used in desktop PCs.
• In general, ATA/IDE is considered easier to
implement and less expensive than SCSI but does
not offer as many features.
– For example, SCSI can support up to 16 devices on a single
bus (IDE offers two), generally offers faster throughput, uses
less CPU horsepower during operation, and is therefore
more efficient in demanding multiple initiator applications for
multi-users and uses. This is significant because it allows the
processor to perform more commands at one time making
for greater efficiency.
SCSI Standards
S
C
SI
Fast
SCSI
Ultra
SCSI
Wide
Ultra
SCSI
Ultra2
SCSI
Wide
Ultra2
SCSI
Ultra3
SCSI
Data transfer rates max.
Bus speed (MB/sec)
5
10
20
40
40
80
160
Maximum Data Bus
width (bits)
8- 8-bit
bit
8-bit
16-bit
8-bit
16-bit
16-bit
Max. cable length
(meters)
6
3
1.5 - 3
1.5 - 3
12
12
12
Max. device support
8
8
8-4
8-4
8
16
16
SCSI Terms (source: IBM)
• The SCSI terms Fast, Ultra, or Ultra2 typically
refer to data rate increases that move data
faster on the bus, while the term Wide refers
to adding more lanes to the bus, typically
transferring 16 bits of data at one time rather
than eight bits. Other differences between the
standards include the maximum cable length
and the number of devices that can exist on
the same SCSI bus.
Ultra 3 SCSI (source: IBM)
•As one of the recent developments in SCSI, Ultra3 SCSI
presents significant feature and benefit enhancements
over Ultra2 SCSI products. Ultra3 SCSI products are
designed to offer, at a minimum, the following features:
Cyclic Redundancy Check (CRC) , domain validation ,
and double transition clocking , none of which are
available in Ultra2 SCSI products.
•These features are designed to improve speed,
performance, and overall manageability of SCSI.
Ultra 160 (source: IBM)
• The subset of Ultra3 that includes the three
features, Cyclic Redundancy Check (CRC) ,
domain validation , and double transition
clocking , is commonly called Ultra160, for its
speed 160MB per/sec. The main difference
between Ultra3 and Ultra160 is that Ultra3
implementations may offer other features in
addition to those listed above.
ATA
• The term ATA stands for Advanced Technology
Attachment, for the standard bus interface on the
original IBM AT computer. This interface also is
called IDE, for Integrated Drive Electronics; ATA is
the official ANSI (American National Standard
Institute) standard designation.
• Also known as Ultra DMA, ATA is generally the
least expensive hard drive interface; many computer
motherboards include ATA controllers and cable
connectors that typically control the "C" drive that
contains the operating system. However, ATA is a
slightly slower drive interface, so it is used primarily
in single user computer applications or low-end
RAID systems.
ATA Variations
ATA/
ATA-2
Ultra-ATA/33 Ultra-ATA/66
Data transfer rates
max. Bus speed
(MB/sec)
8.3
16.6
33
66
Maximum Data Bus
width (bits)
16-bit
16-bit
16-bit
16-bit
Max. device support
2
2
2
2
Serial ATA (SATA)
Fiber-Channel
• Fiber Channel - Arbitrated Loop (FC-AL) is
an exceptionally high-bandwidth industrystandard interface primarily targeted toward
high-end servers and similar demanding
applications.
• FC-AL uses fiber optic cabling in a loop
configuration to produce maximum transfer
speeds of 100 MB/second and is designed to
connect up to 127 devices as far as 10
kilometers apart, enabling data storage in
remote, secure locations distant from the
server.
More on Fiber Channel
• FC-AL devices can be dual ported, providing
two simultaneous input/output sessions that
doubles maximum throughput, and FC-AL
enables "hot swapping," so you can add and
remove hard drives without interrupting
system operation, an important option in
server environments.
• FC-AL adapters tend to cost more than SCSI
adapters.
PCI BUS Technology
• PCI is preferred
– 32-bit and 64-bits
• PCI-X
– An extension to the PCI Bus interface
• General PCI standards
– PCI 1.0, 2.0 and 3.0
• PCI Express
A Note on PCI-X 2.0
(Source PCISIG)
• PCI-X 2.0 is an evolutionary, backward
compatible technology that builds on the
foundation of PCI and PCI-X while offering
bandwidths 4 times higher than PCI-X
without increasing pin-count.
• These new, higher bandwidths are ideal for
server-oriented adapter cards in the areas of
Fibre Channel, RAID, networking,
InfiniBand™ Architecture, SCSI, iSCSI, and
other high-bandwidth technologies.
PCI-X 2.0 Performance
Advantage (Source PCISIG)
• Doubles and Quadruples PCI-X
bandwidth.
• Enables 10Gb Ethernet, 10Gb Fiber
Channel, InfiniBand™ Architecture,
and other IO technologies.
• Performance 32 times higher than the
first generation of PCI.
Desired Characteristics of Server:
Bus and Memory Technologies
• Better bus technology
– PCI
• Memory
– In excess of 512 Mbytes
– SDRAM or similar memory technology
functioning at 10 nanoseconds or less
– The 168-pin SDRAM is also known as the DIMM
chips as opposed to the 72-pin SIMM chips
– 182 DDR RAM
– Rambus RAM
Desired Characteristics of Server:
Reliability
• Good back-up facilities
– Back-up tape
• Uninterruptible Power Supply (UPS)
Fault Tolerant Feature for
Servers
• RAID storage technology
– A system based on multiple disk
– Hot-swappable disks
• Redundant power supply
– Hot-swappable power supply
Hot Pluggable and Hot
Swappable
• Hot Pluggable
– When a card or a device is plugged into the
computer (PCI), the computer will recognize the
device automatically and install the device
• An example is a NIC
• Hot Swappable
– A device that can be removed and replaced
without having switch off the computer
• An example is a hard drive
Workstation
• Most applications are executed at the
workstation in the case of a file server
• Therefore, it must be powerful in terms
of the processor and the memory
• As a rule of thumb, the workstation
must be as powerful as it were to be
used as a standalone unit to run the
applications
Workstation Processor and
Memory
• Powerful processor
– Pentium class processor
• Adequate memory
– 32 Mbytes or more
– DIMM preferred although fast EDO SIMM
may also be used
Workstation Storage and
Compatibility
• Sufficient storage
– Storage in gigabytes
– Important in a client-server environment
– Front-end tools are stored on the
workstation
• Speed of storage
– Ultra DMA or SCSI preferred
– EIDE may also be used
• Hardware components with appropriate
drivers for the client operating system
Reliability
• Power surge protector
• Uninterruptible Power Supply (UPS),
for critical applications
END OF MODULE
MODULE
Repeater
An Overview of Repeaters
• Used for extending the physical span of
a network
– An example is the extension of the distance
between a hub and a node
• Span is often limited by design
considerations
• 10base5
– The span is limited to 500 meters
A Repeater Connection
Expanding the Span of the Network
Source: Black Box
Another Example of Repeater
Connection
Extending the distance between the backbone and the nodes.
Source: Black Box
Current Day Use of Repeaters
• Fiber optic repeaters are used for
extending the distance between two
nodes in a link or a network
Operations of a Repeater Within
the ISO OSI Model
• Operates at the lower level of the ISO
OSI model, namely layer 1
– Physical layer
Physical
Layer
Medium
Repeater
Physical
Layer
Medium
Other Devices Used for
Extending the Span of a Network
• Line Drivers
• Short-Haul Modems
Another Layer 1 Device
• Hub
– This is simply an electrical connecting
device used in the configuration of a
network
• The topology in this case would be that of a
star topology
END OF MODULE
MODULE
Bridge
An Overview of a Bridge
• A device used for connecting two LANs
operating usually under the same protocol
– There are bridges that connect LAN segments
operating under different protocols
• Currently, the term bridge is loosely being
used to describe different interconnecting
devices
– Used now for connecting LANs operating under
different protocols as well
Purpose of a Bridge
• Facilitate the movement of data packet
from one network segment to another
• Not a sophisticated internetworking
device
• Bridge does not perform the routing of
information to different segments of a
network
• Connects two network segments and
not multiple network segments
Bridge : ISO-OSI Layer of
Operation
Data
Link
Layer
Data
Link
Layer
Bridge
Physical
Layer
Physical
Layer
X Medium
X Medium
A simple bridge operates at the
second layer of the ISO model.
Practical Bridge Implementations
• Local Bridge
• Remote Bridge
Local and Remote Bridges
• Local bridge
– Connects two different LANs located
locally
• Remote bridge
– Connects LAN segments that are
geographically apart
– An example is a device that provide dialup access to a LAN
A Practical Bridge Example
END OF MODULE
MODULE
Switch
Switch Definition and Purpose
• A switch is defined as a device that
allows a LAN to be segmented
– The segments will operate under the same
protocol
Difference Between a Switch and
a Bridge
• A switch focuses on segmenting a LAN
• A bridge is concerned with linking two
network segments that operate under
different protocols
Purpose of a Switch
• Improve the network performance and
reliability
• Better manage the network in general
Switch : ISO-OSI Layer of
Operation
Data
Link
Layer
Data
Link
Layer
Switch
Physical
Layer
Physical
Layer
X Medium
X Medium
A simple Switch operates at the
second layer of the ISO model.
Layer 3 Switches
• Some switches operate at Layer 3 of the
ISO-OSI model
• These switches perform routing as well
Performance Improvement in
Segmented Networks
• Performance is improved especially in the
case of a bus network
• Multiple bus paths are now available for
communication
• Each segment can engage in simultaneous
communication within itself
• Easier to isolate a problem to a segment
– Thus, better manage the entire network
Network Reliability
• When one segment does not function,
the other segments can continue to
function
– Offers better reliability to at least part of
the function
Switches in Ethernet and Token
Ring LANs
• Switches were originally designed for
segmenting Ethernet LANs
– Used extensively in configuring large
Ethernet bus LANs
• Physically the network configured would still
largely remain based on the star topology
• Switches are now available for token
ring networks as well
Use of Switches in Linking LAN
Segments
Crossover Traffic
Switch
Segment 2
Segment 1
Hub
WS
Server
Hub
WS
Server
Using A Switch to
Link Bus LAN Segments
Switch
Segment 1
Segment 2
Use of Switches in
Internetworking
• Because the typical inter-networking
connection involves multiple segments,
the use of a switch is more common
than the use of a bridge
Use of Switches for Higher
Bandwidth
100 MBps Switch
WS
WS
WS
WS
Each port in theory has a bandwidth of 100 Mbps.
END OF MODULE
MODULE
Switching Technology
Module Objectives
• Explain the basic operation of a switch
• List the switching technologies and
describe their operation
– Cut-through and store-and-forward
technologies
The Basic Operation of Switches
Receiver’s Address Sender’s Address Data
• A data packet is analyzed
• Receiver’s addresses is checked
• If it indicates the receiver to be in the
same segment, the packet is dropped
• If it indicates the receiver to be in a
different segment, the packet is
Switching Technologies
• There are two major types of switching
technologies
– Cut-through
– Store-and-forward
Cut-Through Technology
• Reads only part of the packet
– The addresses header
– Packet is forwarded accordingly
• Bad packets are not filtered
• Faster
• Less error checking
Store-and-Forward Technology
• Entire packet is processed
• Packets are filtered
– Bad packets are filtered
• Slower
• More error checking
Switching Technology
Comparison
Header
Sender’s Add
Cut-through
Store-and-forward
Receiver’s Add
Data
Switching Technology Operation
at the ISO Layer
• In each of the two cases of switching
technologies no protocol conversion
takes place
• Forwarding and filtering are done at the
MAC layer
• A switch switches the traffic based on
MAC address
Web Research
• Fiber channel
• Clustering
• Load Balancing
END OF MODULE
MODULE
Routers
The Purpose of a Router
• Connect LANs operating under
different protocols
• The LANs connected are better known
as sub-networks instead of network
segments
– The term segments is nevertheless used in
practice
– Each segment basically represents a subnet
Router Characteristics
• A router is a true internetworking device
– Connects different sub-networks together
• Establishes a logical path of communication
between the sub-networks
• Contributes to the modular construction of a
network
– Network itself is better managed
– Network resources are better utilized
Internetworking with a Router
IEEE 802.3
Sub-network
Router
PC-NFS
Sub-network
IEEE 802.5
Sub-network
Routers, Switches and Hubs in
Perspective
Backbone
Router
Switch
Switch
Hub
S
WS
Hub
S
Sub-network 1
WS
Hub
WS
S
Hub
WS
WS
S
WS
Sub-network 2
Difference Between Routers,
Switches and Hubs
• Hubs
– Simply provides the mechanical and electrical connections
between the nodes
• Switches
–
–
–
–
Examine the data packet for the destination address
Do not alter the data packets
Switches based on MAC address
Basically a Layer 2 device
• Routers
–
–
–
–
Examine and alter the data packet format
Perform protocol conversion
Routes based on IP address
Basically a Layer 3 device
Router Requirements
• Requires more processing power
compared to switches and bridges
• Operations fall within the network
layer of the ISO-OSI communication
model
Router : Network Layer Interface
NETWORK
LAYER
DATA LINK
LAYER
ROUTER
NETWORK
LAYER
DATA LINK
LAYER
PHYSICAL
LAYER
PHYSICAL
LAYER
X MEDIUM
X MEDIUM
Layer 3
Layer 2
Layer 1
Switches
Devices and Layers
NETWORK
LAYER
Routers
DATA LINK
LAYER
Switches
PHYSICAL
LAYER
Hubs and
Repeaters
A Practical Router Example
Router
Router
Router
Router
Router
END OF MODULE
MODULE
Gateway
Web Exercise
• Build a small network consisting of 4
workstations and 1 server for a small business
– Provide details of the hardware in terms of the
types of hardware and the cost of the hardware
• Connect the network to the Internet
– Again provide the cost associated with the
hardware required to make the connection
• In both of the above cases, also provide a
schematic diagram showing the network
connections
An Introduction to Gateways
• Gateways are comprehensive
internetworking devices
• They can be computers themselves
Gateways in the Past
• Very popular
• They were the only devices that could
be used for internetworking
• Computers of the past were not
designed with network connections in
mind
– Interconnection of different computer
systems has to be managed and driven by
an advanced device such as a gateway
The Present Scenario
• Computers are now designed with due
consideration given to network connections
• Larger networks could today be configured
using internetworking devices
– Routers, switches, hubs etc.
• Even, mainframes can be connected easily
using the above internetworking devices
• In the past, because of the different nature of
the network (SNA), connecting a mainframe
to a LAN often required a gateway (SAN
Gateway)
Use of Gateways at Present
• Used in the rare occasion when neither
of the internetworking devices could be
used for connecting the sub-networks
together
• Example
– Connection of a legacy mainframe system
to a bus LAN
Rule of Thump
• Gateways are used for interconnecting
vastly differing computing
environments together
SNA Gateway
SNA
Gateway
NIC Card
WS
WS
LAN - Ethernet
FEP
Mainframe
Gateway
Interface
Card
Gateway
software
IBM - SNA
Gateway’s Functional Relationship
to the ISO-OSI Model
Application
Application
Presentation
Presentation
Session
Session
Transport
Transport
Network
Network
Data Link
Data Link
Physical
Physical
END OF MODULE
END OF MODULE
END OF CHAPTER