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Introducing Protocols

Unit objectives Discuss access protocols Discuss transport protocols Discuss remote access protocols Discuss security protocols

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Topic A

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

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

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Ethernet topologies

Some Ethernet topologies (pg 4-9)– 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

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Token Ring and 802.5

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

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– 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

continued

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NetBIOS

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 large-sized 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

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)

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Serial Line Internet Protocol (SLIP)

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

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Point-to-Point Protocol (PPP)

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

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

Learned about access protocols Discussed channel access methods Learned about transport protocols Discussed remote access protocols Learned about security protocols