Download networking hardware (networking devices)

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.
3
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 signals
Convert 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 Speed
Type of System Bus:
ISA, EISA, Microchanel, PCI, PCIMCA)
 Some NICs connect through SCSI bus
 Some NICs use USB
 Integrated on the Motherboard

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AN ETHERNET NIC
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TYPES OF NETWORK ADAPTERS
 PCMIA


Developed in early 1990s to provide standard interface for
connecting any type of device to a portable computer
More commonly known as PC Cards
 USB

(universal serial bus) port
Standard 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
 PCMIA


Developed in early 1990s to provide standard interface for
connecting any type of device to a portable computer
More commonly known as PC Cards
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TYPES OF NETWORK ADAPTERS
 USB
(universal
serial bus) port

Standard 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
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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
Segment
Extend
expand the network
network to filter traffic
network to connect separate LANs
Connect
two separate computer environments
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DEVICES TO EXPAND NETWORKS
Repeaters
Bridges
Switches
Routers
Gateway
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INTERNETWORK CONNECTIVITY DEVICES
 Routers
 Gateways
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REPEATERS





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.
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REPEATERS
 Repeaters


Clean and boost digital transmission
Analog networks use amplifiers to boost signal
 Repeaters

repeat signals
only work with the physical signal
Cannot reformat, resize, or manipulate the data
 Physical
layer (layer 1) device.
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REPEATERS
23
REPEATERS
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HUB
 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
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HUB
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ADVANTAGES AND DISADVANTAGES
OF REPEATERS AND HUBS
 Advantages



of using repeaters
Extend network physical distance
Do not seriously affect network performance
Special repeaters connect different media

Copper to fiber
 Disadvantages

Cannot connect different network architectures


of using repeaters
Token Ring and Ethernet
Cannot reduce network traffic
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ADVANTAGES AND DISADVANTAGES
OF REPEATERS AND HUBS
 Disadvantages
of using repeaters
 Do not segment the network


Repeat everything without discrimination
Number of repeaters must be limited
 Repeaters
are part of a collision domain
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BRIDGES
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 frames
 Cannot filter broadcasts
 MAC to segment # table
 MAC to segment # table initial development
 Make decision based on the MAC address list
Connect different architectures and Forward packets
between architectures: Ethernet & Token-Ring. 29
MAC ADDRESS







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 30
has never used on another card
BRIDGES
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BRIDGES
Creating a Forwarding Table
• Based on the addresses of the sending computers
• New addresses are added if they are not in the table
Add02
S 02
D 01
Forwarding table
Seg 1
Seg 2
01
Add01
Stop
02
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Add03
S 01
D 02
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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ADVANTAGES AND DISADVANTAGES
OF BRIDGES
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SWITCHES
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.

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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
 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
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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.
Preamble
7
Bytes
Des. Add Sour. Add Length
1
Byte
2/6
Bytes
2/6
Bytes
2
Bytes
Data
46 - 1500 Bytes
FCS
4
Bytes
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TYPES OF SWITCHES
- STORE AND FORWARD
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.
 Store
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TYPES OF SWITCHES
- ERROR FREE CUT THROUGH
SWITCHES
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.
 Error
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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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USING SWITCHES TO CREATE
VLANS
SW1
SW2
SW3
VLAN1
VLAN2
Hub
Hub
Switches can
be configured
to communicate
only within the
devices in the
group
Hub
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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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SWITCHES
 Advantages




of switches
Increase available network bandwidth
Reduced workload, computers only receive packets
intended for them specifically
Increase network performance
Smaller collision domains
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SWITCHES
 Disadvantages



of switches
More expensive than hubs and bridges
Difficult to trace network connectivity problems
through a switch
Does not filter broadcast traffic
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SWITCHES
50
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
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IP protocol.
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.

52
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 of54
the packet to retrieve the network destination address

ROUTER FEATURES AND FUNCTIONS
 Static

routing
Technique 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
 Hop

Term used in networking to describe each trip data take
from one connectivity device to another
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ROUTER FEATURES AND FUNCTIONS
Static Routers
Dynamic Routers
Manual configuration Manual configuration of the first
of routes
route. Automatic discovery of new
routes
Always use the same Can select the best route
route
More secure
Need manual configuration to
improve security
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ROUTER FEATURES AND FUNCTIONS
57
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 overhead


Convergence time
 The time it takes for a router to recognize a best path in
the event of a change or outage
Bandwidth overhead
 Burden placed on an underlying network to support the
routing protocol
58
ROUTING PROTOCOLS
 The




four most common routing protocols:
RIP (Routing Information Protocol) for IP and IPX
OSPF (Open Shortest Path First) for IP
EIGRP (Enhanced Interior Gateway Routing Protocol)
for IP, IPX, and AppleTalk
BGP (Border Gateway Protocol) for IP
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BROUTERS AND ROUTING
SWITCHES
 Bridge


router
Also called a brouter
Industry 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



addresses
Data Link layer application
Used by switches, bridges, and routers
Used for directly connected devices
 Logical



addresses
Network and transport protocols dictate the format of
the logical network layer address
TCP/IP, IPX/SPX
IP addresses are assigned manually or by software
61
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 analyzing

62
ROUTERS
63
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 gateways
IBM host gateways
Internet gateways
LAN gateways
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