Transcript Document

Course ILT
Introducing Protocols
Unit objectives
 Discuss access protocols
 Discuss transport protocols
 Discuss remote access protocols
 Discuss security protocols
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Topic A
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Topic A: Introduction to protocols
Topic B: Channel access methods
Topic C: Transport protocols
Topic D: Remote access protocols
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IEEE 802 series
 The 802 series of specifications was
named after the date when the IEEE
Computer Society “Local Network
Standards Committee,” Project 802,
held their first meeting, which was in
February (2) of 1980(80)
 The 802 series of specifications define
the physical media for each
specification (802.3, 802.4, 802.5, and
so on)
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Protocol compatibility
 A computer, by using one protocol,
cannot communicate directly with a
computer that uses a different
protocol
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Access protocols
 The Data Link layer specifies how
devices attached to the network can
gain access to network resources
 The Institute of Electrical and
Electronic Engineers (IEEE)
modified the OSI reference model by
breaking the data link layer into two
additional layers
– Media Access Control (MAC) layer
– Logical Link Control (LLC) layer
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The Data Link layer - Modified
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Activity A-1
Identifying protocols
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Topic B
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Topic A: Introduction to protocols
Topic B: Channel access methods
Topic C: Transport protocols
Topic D: Remote access protocols
Topic E: Security protocols
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Channel access methods
 Determine the physical methodology
by which data is sent across the
transmitting media
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Introducing Ethernet
 CSMA/CD networks are more
popularly known as Ethernet networks
 Ethernet and 802.3 are CSMA/CD
specifications
 CSMA/CA
 The most common implementation of
contention access
– Does not detect collisions as much as it
attempts to avoid collisions (??)
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Data collisions
Ethernet topologies
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 Some Ethernet topologies (pg 4-9)
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10Base-T
10Base-FL
100Base-TX
100Base-FX
1000Base-TX
1000Base-CX
1000Base-SX
1000Base-LX
10Base-SR
10Base-LR
10Base-ER
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Activity B-1
Discussing Ethernet methods
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Introducing token passing/Token Ring
 A token is passed among the nodes of
the network
 Whichever node is in possession of
the token is permitted to transmit
Token Ring and 802.5
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 Features of Token Ring include
– Logical ring usually wired as a physical
star
– Transfer rate of 4 to 16 Mbps
– Unshielded twisted pair, shielded
twisted pair, or fiber optic cable
– Deterministic, it is possible to predict
the passage of the token
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Beaconing
 The beacon frame is used to define a
failure domain
 The failure domain includes the
station reporting the failure, its
nearest active upstream neighbor
(NAUN), and everything in between
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Failure domain
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FDDI
 Uses a double fiber ring
 The secondary ring is for
redundancy
 Runs at 100 Mbps
 It is typically found as the backbone
connecting buildings on a campus or
wider area, as nodes can be over 60
miles apart
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ATM
 Topology that can reach throughput of
almost 10000 Mbps – (WAN)
 Is more commonly implemented at
155 or 622 Mbps
 Uses small packets, which are called
cells
 Equipment is expensive
 Smaller organizations will probably go
to the cheaper Gigabit Ethernet
standard
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Activity B-2
Discussing Token Ring methods
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Wireless – 802.11 and 802.11x
 IEEE 802.11 is a group of
specifications for wireless networks
 Among others, specifications include
802.11, 802.11a, 802.11b and
802.11g
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Wireless
 802.11x wireless networks consist of
Wireless Access Points (WAPs) and
wireless clients
 WAPs operate at the Physical and
Media Access Control (MAC) layer
of the OSI model
 WAPs can, on average, communicate
with up to 30 clients within a 100
meter radius
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Frequency Hopping Spread Spectrum
 Frequency Hopping Spread Spectrum
(FHSS) uses a wide range of
frequencies in the 2.4 Ghz band
 Data is transmitted on a single
frequency at any given time, however,
the signal hops from frequency to
frequency in a pseudorandom pattern
 This transmission technology can be
used by 802.11
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Direct Sequence Spread Spectrum
 Direct Sequence Spread Spectrum
(DSSS) also operates in the 2.4 Ghz
band
 It employs a mechanism whereby the
data being transmitted is spread over
multiple frequencies, allowing for
higher throughput rates
 DSSS is used by the 802.11b and
802.11g standards
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Orthogonal frequency division multiplexing
 With Orthogonal Frequency Division
Multiplexing, the radio signal is split
into multiple, smaller signals
 These signals are transmitted at the
same time, but at different
frequencies
 OFDM operates in the 5 Ghz band,
which makes it more resistant to
interference than FHSS and DSSS
 OFDM is used by the 802.11a standard
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Bluetooth
 Bluetooth’s aim is to allow the creation
of small, short range, wireless
networks, usually within a single room
 It has a range of 10 meters, speeds of
up to 1 Mbps and uses FHSS
 Bluetooth and 802.11x devices cannot
communicate with one another
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Infrared
 Infrared (IR)allows for wireless
connection of devices at very close
range
 It is line of sight technology
 Infrared’s range is up to 1 meter and
speeds range from 115 Kbps to 4
Mbps
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Activity B-3
Discussing wireless communications
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Topic C
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Topic A: Introduction to protocols
Topic B: Channel access methods
Topic C: Transport protocols
Topic D: Remote access protocols
Topic E: Security protocols
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Connectionless protocols
 Used when sending small packets of
data, usually less than 1 KB
 Packets are infrequently dropped
 No need for the increased overhead
of acknowledging each receipt
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Connection-oriented protocols
 Used to send a large amount of
information that is divided into
multiple packets for transmission
 Uses packet sequence numbers to
verify packet order and acknowledges
the receipt of each packet
 The lost or improperly delivered
packets, which are not acknowledged
as a successful receipt, can be
retransmitted
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Transport protocols
 Transport protocols manage network
communications and determine how
data should be presented to the next
layer
 The protocols responsible for
transporting data
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NetBEUI
IPX/SPX
TCP/IP
AppleTalk
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NetBEUI
 NetBEUI (NetBIOS Extended User
Interface) is a high-speed protocol
first introduced by IBM
– Designed for use on small networks
(20-200 nodes
– Provides good error protection
– Provides tuning parameters to match
network and organizational requirements
continued
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NetBEUI
– Has limited memory overhead
requirements
– Supports both connectionless and
connection-oriented traffic
– Is not a routable protocol and so does
not perform well on larger networks
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NetBIOS
 NetBIOS (Network Basic Input/Output
System) is an application interface
operating at the session layer
 By using NetBIOS
– Applications can communicate with
NetBIOS-compliant protocols
– You can manage communication
sessions between computers
– You can track computers by the
computer name
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NetBIOS
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 NetBIOS is supported over NetBEUI
– It can be supported over other
protocols, such as IPX/SPX and TCP/IP
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IPX/SPX
 Internetwork Packet Exchange (IPX)
 Sequenced Packet Exchange (SPX)
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IPX/SPX
 Is a Novell proprietary protocol
 Available as monolithic (old) or
ODI-compliant
 IPX provides connectionless service
 SPX provides connection-oriented
services
 Is a routable protocol
 Is the default NetWare 3.x and 4.x
protocol and supported by NetWare 5.x
and 6.x
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TCP/IP
 The protocol for most medium to largesized networks
 Is the current de facto standard for
internetwork communications
 Provides guaranteed delivery, proper
sequencing, and data integrity
checks
 If errors occur during transmission, TCP
is responsible for retransmitting the
data
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TCP/IP Transport layer protocols
 TCP/IP Transport layer protocols
 User Datagram Protocol (UDP)
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AppleTalk
 AppleTalk is a protocol suite
developed by Apple Corp. in the
1980’s for networks consisting of
Macintosh computers
 The original cabling system used in
these networks is called LocalTalk
 AppleTalk Phase 2 complies with the
IEEE 802 standard and provides
Ethernet support through EtherTalk
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AppleTalk network addresses
 AppleTalk network addresses are 24
bits in length
 16 bits are used for the network
portion and 8 bits for the node’s
address
 The node address is self-assigned
 Given this setup, there can be 65,000
networks with up to 256 nodes each
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Gateway
 Connect incompatible networks at
the fourth through seventh layers of
the OSI model by using protocol
conversion and routing services
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Activity C-1
Discussing transport protocols
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Topic D
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Topic A: Introduction to protocols
Topic B: Channel access methods
Topic C: Transport protocols
Topic D: Remote access protocols
Topic E: Security protocols
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Remote access protocols
 Protocols provide a serial connection
to a network device, such as a host
and a router
 The standard protocols include
– Serial Line Internet Protocol (SLIP)
– Point-to-Point Protocol (PPP)
– Point-to-Point Tunneling Protocol
(PPTP)
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Serial Line Internet Protocol (SLIP)
 SLIP defines a sequence of characters
that frame IP packets over a serial line
 The protocol was devised to handle
communications over fairly slow links
(<19.2 Kbps)
Serial Line Internet Protocol (SLIP)
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 Disadvantages include
– Inability to provide packet addressing
– Inability to provide any packet ID
information
– Lack of error detection or error
correction mechanisms
– Lack of compression mechanisms
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Point-to-Point Protocol (PPP)
 Is the current methodology for
transporting multiprotocol datagrams
over point-to-point links
 Defined to be a multiprotocol
transport over serial links and
therefore, can support TCP/IP, IPX,
DECNet, CLNP, AppleTalk, and other
protocol datagrams
Point-to-Point Protocol (PPP)
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 Advantages include
– Ability to employ data compression
techniques
– Link quality monitoring
– Ability to support security features such
as confirming the identity of users
attempting to establish a connection
– Mechanisms for error detection and
error correction
– Ability to provide a higher level of
security through encryption
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Point-to-Point Tunneling Protocol
 Remote clients can access the
corporate network across the Internet
securely
 You can configure PPTP filtering on a
network adapter so that only PPTP
packets are permitted
 Operates across PPP connections
 Data is encrypted and encapsulated
inside PPP packets
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Point-to-Point Protocol over Ethernet
 Point-to-Point Protocol over
Ethernet (PPPoE) is derived from the
PPP protocol
 Was designed to provide secure
connectivity to the Internet for
broadband connections that use an
Ethernet rather than a serial
connection
 PPPoE is defined in RFC 2516
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Remote Desktop Protocol
 Remote Desktop Protocol (RDP) is
part of Windows NT Terminal Server
and Windows 2000/2003 Terminal
Services
 RDP enables display of and input into
applications running on a remote
Windows computer
 RDP operates at the Application
layer of the OSI model
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Activity D-1
Discussing remote access protocols
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Topic E
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Topic A: Introduction to protocols
Topic B: Channel access methods
Topic C: Transport protocols
Topic D: Remote access protocols
Topic E: Security protocols
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Internet Protocol Security
 Internet Protocol Security (IPSec) is
a suite of protocols
 It’s used to encrypt data packets
 It uses one of two modes of
encryption, transport or tunnel
 Transport mode is less secure than
tunnel mode
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Layer 2 Tunneling Protocol
 Layer 2 Tunneling Protocol (L2TP) is
an extension to the PPP protocol
 It’s an enhanced tunneling protocol
used in VPN implementations
 Supports multiple protocols
 Is optimized to work with IPv6 and
IPSec
 Operates at the Data Link layer of the
OSI model
 Is defined in RFC 2661
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Secure Sockets Layer
 Secure Sockets Layer (SSL) was
developed by Netscape
 Enables secure, reliable
transmissions over the Internet
 Is supported by both Internet Explorer
and Netscape Navigator
 Uses a private and public key system
(RSA) to encrypt and decrypt data
transmissions
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Wired Equivalent Privacy
 Wired Equivalent Privacy (WEP) is a
security protocol for secure data
transmission in wireless LANs
(WLANs)
 It was intended to simulate the
physical security of a wired LAN
 Uses a single, manually configured,
static key for data encryption
 WEP is not as secure as originally
believed
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Wi-Fi Protected Access
 Wi-Fi Protected Access (WPA) was
developed to improve on WEP’s
functionality
 Provides for user authentication
using the Extensible Authentication
Protocol (EAP)
 Data encryption is more secure
through the use of the Temporal Key
Integrity Protocol (TKIP)
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802.1x
 801.1x is a standard that uses EAP for
user authentication in 802.11
wireless networks
 A supplicant (client) requests access
to the wireless network from an
authenticator (access point)
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Activity E-1
Discussing security protocols
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Unit summary
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Learned about access protocols
Discussed channel access methods
Learned about transport protocols
Discussed remote access protocols
Learned about security protocols