Table 1.1 Communications Tasks

Transmission system utilization Interfacing Signal generation Synchronization Exchange management Error detection and correction Flow control

Addressing Routing Recovery Message formatting Security Network management

Table 1.2 Internet Terminology Central Office (CO) The place where telephone companies terminate customer lines and locate switching equipment to interconnect those lines with other networks. Customer Premises Equipment (CPE) Telecommunications equipment that is located on the customer's premises (physical location) rather than on the provider's premises or in between. Telephone handsets, modems, cable TV set-top boxes, and digital subscriber line routers are examples. Historically, this term referred to equipment placed at the customer's end of the telephone line and usually owned by the telephone company. Today, almost any end-user equipment can be called customer premises equipment and it can be owned by the customer or by the provider. Internet Service Provider (ISP) A company that provides other companies or individuals with access to, or presence on, the Internet. An ISP has the equipment and the telecommunication line access required to have a POP on the Internet for the geographic area served. The larger ISPs have their own high-speed leased lines so that they are less dependent on the telecommunication providers and can provide better service to their customers. Network Access Point (NAP) In the United States, a network access point (NAP) is one of several major Internet interconnection points that serve to tie all the ISPs together. Originally, four NAPs - in New York, Washington, D.C., Chicago, and San Francisco - were created and supported by the National Science Foundation as part of the transition from the original U.S. government-financed Internet to a commercially operated Internet. Since that time, several new NAPs have arrived, including WorldCom's "MAE West" site in San Jose, California and ICS Network Systems' "Big East." The NAPs provide major switching facilities that serve the public in general. Companies apply to use the NAP facilities. Much Internet traffic is handled without involving NAPs, using peering arrangements and interconnections within geographic regions. Network Service Provider (NSP) A company that provides backbone services to an Internet service provider (ISP). Typically, an ISP connects at a point called an Internet exchange (IX) to a regional ISP that in turn connects to an NSP backbone. Point of Presence (POP) A site that has a collection of telecommunications equipment, usually refers to ISP or telephone company sites. An ISP POP is the edge of the ISP's network; connections from users are accepted and authenticated here. An Internet access provider may operate several POPs distributed throughout its area of operation to increase the chance that their subscribers will be able to reach one with a local telephone call. The largest national ISPs have POPs all over the country.

Table 2.1 Service Primitive Types

REQUEST

A primitive issued by a service user to invoke some service and to pass the parameters needed to specify fully the requested service

INDICATION

A primitive issued by a service provider either to 1. indicate that a procedure has been invoked by the peer service user on the connection and to provide the associated parameters, or 2. notify the service user of a provider-initiated action

RESPONSE

A primitive issued by a service user to acknowledge or complete some procedure previously invoked by an indication to that user

CONFIRM

A primitive issued by a service provider to acknowledge or complete some procedure previously invoked by a request by the service user

Table 2.2 Multimedia Terminology Media Refers to the form of information and includes text, still images, audio, and video. Multimedia Human-computer interaction involving text, graphics, voice and video. Multimedia also refers to storage devices that are used to store multimedia content. Streaming media Refers to multimedia files, such as video clips and audio, that begin playing immediately or within seconds after it is received by a computer from the Internet or Web. Thus, the media content is consumed as it is delivered from the server rather than waiting until an entire file is downloaded.

Table 2.3 Domains of Multimedia Systems and Example Applications Domain

Example Application

Information management

Hypermedia, multimedia-capable databases, content-based retrieval

Entertainment

Computer games, digital video, audio (MP3)

Telecommunication

Videoconferencing, shared workspaces, virtual communities

Information publishing/delivery

Online training, electronic books, streaming media

Table 2.4 TFTP Error Codes Value

Meaning

0

Not defined, see error message (if any)

1

File not found

2

Access violation

3

Disk full or allocation exceeded

4

Illegal TFTP operation

5

Unknown transfer ID

6

File already exists

7

No such user

Table 3.1 Analog and Digital Transmission (a) Data and Signals Analog Signal Analog Data

Digital Data

Digital Signal

Two alternatives: (1) signal occupies the same spectrum as the analog data; (2) analog data are encoded to occupy a different portion of spectrum.

Analog data are encoded using a codec to produce a digital bit stream.

Digital data are encoded using a modem to produce analog signal.

Two alternatives: (1) signal consists of two voltage levels to represent the two binary values; (2) digital data are encoded to produce a digital signal with desired properties.

(b) Treatment of Signals Analog Transmission

Analog Signal

Digital Signal

Digital Transmission

Is propagated through amplifiers; same treatment whether signal is used to represent analog data or digital data.

Assumes that the analog signal represents digital data. Signal is propagated through repeaters; at each repeater, digital data are recovered from inbound signal and used to generate a new analog outbound signal.

Not used

Digital signal represents a stream of 1s and 0s, which may represent digital data or may be an encoding of analog data. Signal is propagated through repeaters; at each repeater, stream of 1s and 0s is recovered from inbound signal and used to generate a new digital outbound signal.

Table 3.2

Decibel Values

Power Ratio

dB

Power Ratio

dB

101

10

10–1

–10

102

20

10–2

–20

103

30

10–3

–30

104

40

10–4

–40

105

50

10–5

–50

106

60

10–6

–60

Table 4.1 Point-to-Point Transmission Characteristics of Guided Media [GLOV98]

Frequency Range

Typical Attenuation

Typical Delay

Repeater Spacing

Twisted pair (with loading)

0 to 3.5 kHz

0.2 dB/km @ 1 kHz

50 µs/km

2 km

Twisted pairs (multipair cables)

0 to 1 MHz

0.7 dB/km @ 1 kHz

5 µs/km

2 km

Coaxial cable

0 to 500 MHz

7 dB/km @ 10 MHz

4 µs/km

1 to 9 km

Optical fiber

186 to 370 THz

0.2 to 0.5 dB/km

5 µs/km

40 km

THz = TeraHertz = 1012 Hz

Table 4.2 Comparison of Shielded and Unshielded Twisted Pair

Attenuation (dB per 100 m) Frequency (MHz)

Category 3 UTP

Category 5 UTP

1

2.6

4

Near-end Crosstalk (dB)

150-ohm STP

Category 3 UTP

Category 5 UTP

150-ohm STP

2.0

1.1

41

62

58

5.6

4.1

2.2

32

53

58

16

13.1

8.2

4.4

23

44

50.4

25

—

10.4

6.2

—

41

47.5

100

—

22.0

12.3

—

32

38.5

300

—

—

21.4

—

—

31.3

Table 4.7 Frequency Bands Band

Frequency Range

ELF (extremely low frequency) VF (voice frequency)

30 to 300 Hz

Free-Space Wavelength Range 10,000 to 1000 km

Propagation Characteristics

300 to 3000 Hz

1000 to 100 km

GW

VLF (very low frequency) LF (low frequency)

3 to 30 kHz

100 to 10 km

30 to 300 kHz

10 to 1 km

MF (medium frequency)

300 to 3000 kHz

1,000 to 100 m

HF (high frequency)

3 to 30 MHz

100 to 10 m

GW; low attenuation day and night; high atmospheric noise level GW; slightly less reliable than VLF; absorption in daytime GW and night SW; attenuation low at night, high in day; atmospheric noise SW; quality varies with time of day, season, and frequency.

VHF (very high frequency)

30 to 300 MHz

10 to 1 m

LOS; scattering because of temperature inversion; cosmic noise

UHF (ultra high frequency)

300 to 3000 MHz

100 to 10 cm

LOS; cosmic noise

SHF (super high frequency)

3 to 30 GHz

10 to 1 cm

EHF (extremely high frequency) Infrared Visible light

30 to 300 GHz

10 to 1 mm

300 GHz to 400 THz 400 THz to 900 THz

1 mm to 770 nm 770 nm to 330 nm

LOS; rainfall attenuation above 10 GHz; atmospheric attenuation due to oxygen and water vapor LOS; atmospheric attenuation due to oxygen and water vapor LOS LOS

GW

Typical Use Power line frequencies; used by some home control systems. Used by the telephone system for analog subscriber lines. Long-range navigation; submarine communication Long-range navigation; marine communication radio beacons Maritime radio; direction finding; AM broadcasting. Amateur radio; international broadcasting, military communication; long-distance aircraft and ship communication VHF television; FM broadcast and two-way radio, AM aircraft communication; aircraft navigational aids UHF television; cellular telephone; radar; microwave links; personal communications systems Satellite communication; radar; terrestrial microwave links; wireless local loop Experimental; wireless local loop Infrared LANs; consumer electronic applications Optical communication

Table 4.3 Twisted Pair Categories and Classes

Category 3 Class C

Category 5 Class D

Category 5E

Category 6 Class E

Category 7 Class F

Bandwidth

16 MHz

100 MHz

100 MHz

200 MHz

600 MHz

Cable Type

UTP

UTP/FTP

UTP/FTP

UTP/FTP

SSTP

Link Cost (Cat 5 =1)

0.7

1

1.2

1.5

2.2

UTP = Unshielded twisted pair FTP = Foil twisted pair SSTP = Shielded screen twisted pair

Table 4.4 High Performance LAN Copper Cabling Alternatives [JOHN98] Name

Category 5 UTP

Enhanced Cat 5 UTP (Cat 5E)

Category 6 UTP

Foil Twisted Pair

Shielded Foil Twisted Pair

Category 7 Shielded-Screen Twisted Pair

Construction Cable consists of 4 pairs of 24 AWG (0.50 mm) copper with thermoplastic polyolefin or fluorinated ethylene propylene (FEP) jacket. Outside sheath consists of polyvinylchlorides (PVC), a fire retardant polyolefin or fluoropolymers. Cable consists of 4 pairs of 24 AWG (0.50 mm) copper with thermoplastic polyolefin or fluorinated ethylene propylene (FEP) jacket. Outside sheath consists of polyvinylchlorides (PVC), a fire retardant polyolefin or fluoropolymers. Higher care taken in design and manufacturing. Cable consists of 4 pairs of 0.50 to 0.53 mm copper with thermoplastic polyolefin or fluorinated ethylene propylene (FEP) jacket. Outside sheath consists of polyvinylchlorides (PVC), a fire retardant polyolefin or fluoropolymers. Extremely high care taken in design and manufacturing. Advanced connector designs. Cable consists of 4 pairs of 24 AWG (0.50 mm) copper with thermoplastic polyolefin or fluorinated ethylene propylene (FEP) jacket. Pairs are surrounded by a common metallic foil shield. Outside sheath consists of polyvinylchlorides (PVC), a fire-retardant polyolefin or fluoropolymers. Cable consists of 4 pairs of 24 AWG (0.50 mm) copper with thermoplastic polyolefin or fluorinated ethylene propylene (FEP) jacket. Pairs are surrounded by a common metallic foil shield, followed by a braided metallic shield. Outside sheath consists of polyvinylchlorides (PVC), a fire retardant polyolefin, or fluoropolymers. Also called PiMF (for Pairs in Metal Foil), SSTP of 4 pairs of 22-23AWG copper with a thermoplastic polyolefin or fluorinated ethylenepropylene (FEP) jacket. Pairs are individually surrounded by a helical or longitudinal metallic foil shield, followed by a braided metallic shield. Outside sheath of polyvinylchlorides (PVC), a fire-retardant polyolefin, or fluoropolymers.

ACR = Attenuation to crosstalk ratio EMI = Electromagnetic interference

Expected Performance Mixed and matched cables and connecting hardware from various manufacturers that have a reasonable chance of meeting TIA Cat 5 Channel and ISO Class D requirements. No manufacturer's warranty is involved. Category 5 components from one supplier or from multiple suppliers where components have been deliberately matched for improved impedance and balance. Offers ACR performance in excess of Cat 5 Channel and Class D as well as a 10-year or greater warranty. Category 6 components from one supplier that are extremely well matched. Channel zero ACR point (effective bandwidth) is guaranteed to 200 MHz or beyond. Best available UTP. Performance specifications for Category 6 UTP to 250 MHz are under development. Category 5 components from one supplier or from multiple suppliers where components have been deliberately designed to minimize EMI susceptibility and maximize EMI immunity. Various grades may offer increased ACR performance. Category 5 components from one supplier or from multiple suppliers where components have been deliberately designed to minimize EMI susceptibility and maximize EMI immunity. Offers superior EMI protection to FTP.

Cost

1

1.2

1.5

1.3

1.4

Category 7 cabling provides positive ACR to 600 to 1200 MHz. Shielding on the individual pairs gives it phenomenal ACR. 2.2

Table 4.5 Frequency Utilization for Fiber Applications Fiber Type

Application

Multimode

LAN

S

Single mode

Various

196 to 192

C

Single mode

WDM

192 to 185

L

Single mode

WDM

Wavelength (in vacuum) range (nm)

Frequency Range (THz)

820 to 900

366 to 333

1280 to 1350

234 to 222

1528 to 1561 1561 to 1620

Band Label

WDM = wavelength division multiplexing (see Chapter 8)

Table 4.6 Typical Digital Microwave Performance

Band (GHz)

Bandwidth (MHz)

Data Rate (Mbps)

2

7

12

6

30

90

11

40

135

18

220

274

Table 5.1 Key Data Transmission Terms

Term

Units

Definition

Data element

Bits

A single binary one or zero

Data rate

Bits per second (bps)

The rate at which data elements are transmitted

Signal element

Digital: a voltage pulse of constant amplitude

That part of a signal that occupies the shortest interval of a signaling code

Analog: a pulse of constant frequency, phase, and amplitude Signaling rate or modulation rate

Signal elements per second (baud)

The rate at which signal elements are transmitted

Table 5.2 Definition of Digital Signal Encoding Formats

Nonreturn to Zero-Level (NRZ-L) 0 = high level 1 = low level Nonreturn to Zero Inverted (NRZI) 0 = no transition at beginning of interval (one bit time) 1 = transition at beginning of interval Bipolar-AMI 0 = no line signal 1 = positive or negative level, alternating for successive ones Pseudoternary 0 = positive or negative level, alternating for successive zeros 1 = no line signal Manchester 0 = transition from high to low in middle of interval 1 = transition from low to high in middle of interval Differential Manchester Always a transition in middle of interval 0 = transition at beginning of interval 1 = no transition at beginning of interval B8ZS Same as bipolar AMI, except that any string of eight zeros is replaced by a string with two code violations HDB3 Same as bipolar AMI, except that any string of four zeros is replaced by a string with one code violation

Table 5.3  Normalized Signal Transition Rate of Various Digital Signal Encoding Schemes

Minimum

101010. . .

Maximum

NRZ-L

0 (all 0s or 1s)

1.0

1.0

NRZI

0 (all 0s)

0.5

1.0 (all 1s)

Bipolar-AMI

0 (all 0s)

1.0

1.0

Pseudoternary

0 (all 1s)

1.0

1.0

Manchester

1.0 (1010 . . .)

1.0

2.0 (all 0s or 1s)

Differential Manchester

1.0 (all 1s)

1.5

2.0 (all 0s)

Table 5.4

HDB3 Substitution Rules

Number of Bipolar Pulses (ones) since Last Substitution Polarity of Preceding Pulse

Odd

Even

-

000-

+00+

+

000+

-00-

Table 5.5   Bandwidth Efficiency (R/BT) for Various Digital-to-Analog Encoding Schemes

r=0

r = 0.5

r=1

ASK

1.0

0.67

0.5

FSK

0.5

0.75

1.00

  M = 4, L = 2

0.5

0.75

1.00

  M = 8, L = 3

0.375

0.56

0.75

  M = 16, L = 4

0.25

0.375

0.5

  M = 32, L = 5

0.156

0.234

0.312

1.0

0.67

0.5

  M = 4, L = 2

2.00

1.33

1.00

  M = 8, L = 3

3.00

2.00

1.50

  M = 16, L = 4

4.00

2.67

2.00

  M = 32, L = 5

5.00

3.33

2.50

Multilevel FSK

PSK Multilevel PSK

Table 7.1 HDLC Commands and Responses Name Information (I)

Command/ Response

Description

C/R

Exchange user data

Receive ready (RR)

C/R

Positive acknowledgment; ready to receive Iframe

Receive not ready (RNR)

C/R

Positive acknowledgment; not ready to receive

Reject (REJ)

C/R

Negative acknowledgment; go back N

Selective reject (SREJ)

C/R

Negative acknowledgment; selective reject

Supervisory (S)

Unnumbered (U) Set normal response/extended mode (SNRM/SNRME)

C

Set mode; extended = 7-bit sequence numbers

Set asynchronous response/extended mode (SARM/SARME)

C

Set mode; extended = 7-bit sequence numbers

Set asynchronous balanced/extended mode (SABM, SABME)

C

Set mode; extended = 7-bit sequence numbers

Set initialization mode (SIM)

C

Initialize link control functions in addressed station

Disconnect (DISC)

C

Terminate logical link connection

Unnumbered Acknowledgment (UA)

R

Acknowledge acceptance of one of the set-mode commands

Disconnected mode (DM)

R

Responder is in disconnected mode

Request disconnect (RD)

R

Request for DISC command

Request initialization mode (RIM)

R

Initialization needed; request for SIM command

Unnumbered information (UI)

C/R

Used to exchange control information

Unnumbered poll (UP)

C

Used to solicit control information

Reset (RSET)

C

Used for recovery; resets N(R), N(S)

Exchange identification (XID)

C/R

Used to request/report status

Test (TEST)

C/R

Exchange identical information fields for testing

Frame reject (FRMR)

R

Report receipt of unacceptable frame

Table 8.8 Comparison of xDSL Alternatives ADSL Data rate

1.5 to 9 Mbps downstream 16 to 640 kbps upstream

HDSL

SDSL

VDSL

1.544 or 2.048 1.544 or 2.048 13 to 52 Mbps Mbps Mbps downstream 1.5 to 2.3 Mbps upstream

Mode

Asymmetric

Symmetric

Symmetric

Asymmetric

1

2

1

1

3.7 to 5.5 km

3.7 km

3.0 km

1.4 km

Signaling

Analog

Digital

Digital

Analog

Line code

CAP/DMT

2B1Q

2B1Q

DMT

Frequency

1 to 5 MHz

196 kHz

196 kHz

≥ 10 MHz

Bits/cycle

Varies

4

4

Varies

Copper pairs Range (24-gauge UTP)

UTP = unshielded twisted pair

Table 8.1 North American and International FDM Carrier Standards

Number of Voice Channels

Bandwidth

Spectrum

AT&T

ITU-T

12

48 kHz

60–108 kHz

Group

Group

60

240 kHz

312–552 kHz

Supergroup

Supergroup

300

1.232 MHz

812–2044 kHz

600

2.52 MHz

564–3084 kHz

900

3.872 MHz

8.516–12.388 MHz

N × 600

Mastergroup Mastergroup Supermaster group Mastergroup multiplex

3,600

16.984 MHz

0.564–17.548 MHz

Jumbogroup

10,800

57.442 MHz

3.124–60.566 MHz

Jumbogroup multiplex

Table 8.2 ITU WDM Channel Spacing (G.692)

Frequency (THz)

Wavelength in Vacuum (nm)

50 GHz

100 GHz

200 GHz

196.10

1528.77

X

X

X

196.05

1529.16

X

196.00

1529.55

X

195.95

1529.94

X

195.90

1530.33

X

195.85

1530.72

X

195.80

1531,12

X

195.75

1531.51

X

195.70

1531.90

X

195.65

1532.29

X

195.60

1532.68

X

X

…

…

192.10

1560.61

X

X

X X

X

X X

X

X

Table 8.3 North American and International TDM Carrier Standards

North American

International (ITU-T)

Number of Voice Channels

Data Rate (Mbps)

Level

Number of Voice Channels

DS-1

24

1.544

1

30

2.048

DS-1C

48

3.152

2

120

8.448

DS-2

96

6.312

3

480

34.368

DS-3

672

44.736

4

1920

139.264

DS-4

4032

274.176

5

7680

565.148

Designation

Data Rate (Mbps)

Table 8.4 SONET/SDH Signal Hierarchy SONET Designation

ITU-T Designation

STS-1/OC-1

Data Rate

Payload Rate (Mbps)

51.84 Mbps

50.112 Mbps

155.52 Mbps

150.336 Mbps

466.56 Mbps

451.008 Mbps

622.08 Mbps

601.344 Mbps

STS-18/OC-18

933.12 Mbps

902.016 Mbps

STS-24/OC-24

1.24416 Gbps

1.202688 Gbps

STS-36/OC-36

1.86624 Gbps

1.804032 Gbps

2.48832 Gbps

2.405376 Gbps

4.87664 Gbps

4.810752 Gbps

STS-3/OC-3

STM-1

STS-9/OC-9 STS-12/OC-12

STS-48/OC-48

STM-4

STM-16

STS-96/OC-96 STS-192/OC-192

STM-64

9.95328 Gbps

9.621504 Gbps

STS-768

STM-256

39.81312 Gbps

38.486016 Gbps

159.25248 Gbps

153.944064 Gbps

STS-3072

Table 8.5 STS-1 Overhead Bits Section Overhead A1, A2: C1: B1:

E1: F1: D1-D3:

Framing bytes = F6,28 hex; used to synchronize the beginning of the frame. STS-1 ID identifies the STS-1 number (1 to N) for each STS-1 within an STS-N multiplex. Bit-interleaved parity byte providing even parity over previous STS-N frame after scrambling; the ith bit of this octet contains the even parity value calculated from the ith bit position of all octets in the previous frame. Section level 64-kbps PCM orderwire; optional 64-kbps voice channel to be used between section terminating equipment, hubs, and remote terminals. 64-kbps channel set aside for user purposes. 192-kbps data communications channel for alarms, maintenance, control, and administration between sections. Line Overhead

H1-H3: B2: K1, K2: D4-D12: Z1, Z2: E2:

Pointer bytes used in frame alignment and frequency adjustment of payload data. Bit-interleaved parity for line level error monitoring. Two bytes allocated for signaling between line level automatic protection switching equipment; uses a bit-oriented protocol that provides for error protection and management of the SONET optical link. 576-kbps data communications channel for alarms, maintenance, control, monitoring, and administration at the line level. Reserved for future use. 64-kbps PCM voice channel for line level orderwire. Path Overhead

J1: B3: C2:

G1: F2: H4: Z3-Z5:

64-kbps channel used to send repetitively a 64-octet fixed-length string so a receiving terminal can continuously verify the integrity of a path; the contents of the message are user programmable. Bit-interleaved parity at the path level, calculated over all bits of the previous SPE. STS path signal label to designate equipped versus unequipped STS signals. Unequipped means the the line connection is complete but there is no path data to send. For equipped signals, the label can indicate the specific STS payload mapping that might be needed in receiving terminals to interpret the payloads. Status byte sent from path terminating equipment back to path originating equipment to convey status of terminating equipment and path error performance. 64-kbps channel for path user. Multiframe indicator for payloads needing frames that are longer than a single STS frame; multiframe indicators are used when packing lower rate channels (virtual tributaries) into the SPE. Reserved for future use.

Table 8.6 Example of Statistical Multiplexer Performance Capacity = 5000 bps

aInput

Capacity = 7000 bps

Inputa

Output

Backlog

Output

Backlog

6

5

1

6

0

9

5

5

7

2

3

5

3

5

0

7

5

5

7

0

2

5

2

2

0

2

4

0

2

0

2

2

0

2

0

3

3

0

3

0

4

4

0

4

0

6

5

1

6

0

1

2

0

1

0

10

5

5

7

3

7

5

7

7

3

5

5

7

7

1

8

5

10

7

2

3

5

8

5

0

6

5

9

6

0

2

5

6

2

0

9

5

10

7

2

5

5

10

7

0

= 10 sources, 1000 bps/source; average input rate = 50% of maximum.

Table 8.7 Single-Server Queues with Constant Service Times and Poisson (Random) Arrivals

Parameters λ Ts ρ N Tr σr

= = = = = =

mean number of arrivals per second service time for each arrival utilization; fraction of time server is busy mean number of items in system (waiting and being served) residence time; mean time an item spends in system (waiting and being served) standard deviation of Tr

Formulas ρ = λTs N=

ρ2 +ρ 2(1− ρ)

Tr =

Ts (2 − ρ) 2(1− ρ)

1 3ρ 2 5 ρ 3 ρ 4 σr = ρ− + − 1− ρ 2 6 12

€

Table 9.1

CDMA Example

(a) User's codes User A User B User C

1 1 1

–1 1 1

–1 –1 –1

1 –1 1

–1 1 1

1 1 –1

(b) Transmission from A Transmit (data bit = 1) Receiver codeword Multiplication

1 1 1

–1 –1 1

–1 –1 1

1 1 1

–1 –1 1

1 1 1

=6

Transmit (data bit = 0) Receiver codeword Multiplication

–1 1 –1

1 –1 –1

1 –1 –1

–1 1 –1

1 –1 –1

–1 1 –1

= –6

(c) Transmission from B, receiver attempts to recover A's transmission Transmit (data bit = 1) Receiver codeword Multiplication

1 1 1

1 –1 –1

–1 –1 1

–1 1 –1

1 –1 –1

1 1 1

=0

(d) Transmission from C, receiver attempts to recover B's transmission Transmit (data bit = 1) Receiver codeword Multiplication

1 1 1

1 1 1

–1 –1 1

1 –1 –1

1 1 1

–1 1 –1

=2

(e) Transmission from B and C, receiver attempts to recover B's transmission B (data bit = 1) C (data bit = 1) Combined signal Receiver codeword Multiplication

1 1 2 1 2

1 1 2 1 2

–1 –1 –2 –1 2

–1 1 0 –1 0

1 1 2 1 2

1 –1 0 1 0

=8

Table 10.1  Comparison of Communication Switching Techniques

Circuit Switching

Datagram Packet Switching

Virtual Circuit Packet Switching

Dedicated transmission path

No dedicated path

No dedicated path

Continuous transmission of data

Transmission of packets

Transmission of packets

Fast enough for interactive

Fast enough for interactive

Fast enough for interactive

Messages are not stored

Packets may be stored until delivered

Packets stored until delivered

The path is established for entire conversation

Route established for each packet

Route established for entire conversation

Call setup delay; negligible transmission delay

Packet transmission delay

Call setup delay; packet transmission delay

Busy signal if called party busy

Sender may be notified if packet not delivered

Sender notified of connection denial

Overload may block call Overload increases packet setup; no delay for established delay calls

Overload may block call setup; increases packet delay

Small switching nodes Electromechanical or computerized switching nodes

Small switching nodes

User responsible for message loss protection

Network may be responsible for individual packets

Network may be responsible for packet sequences

Usually no speed or code conversion

Speed and code conversion

Speed and code conversion

Fixed bandwidth

Dynamic use of bandwidth

Dynamic use of bandwidth

No overhead bits after call setup

Overhead bits in each packet

Overhead bits in each packet

Table 11.3 Generic Flow Control (GFC) Field Coding

Uncontrolled

Controlling → Controlled

Controlled → Controlling

1-Queue Model

2-Queue Model

1-Queue Model

2-Queue Model

First bit

0

HALT(0)/NO_HALT(1)

HALT(0)/NO_HALT(1)

0

0

Second bit

0

SET(1)/NULL(0)

SET(1)/NULL(0) for Group A

cell belongs to controlled(1) /uncontrolled(0)

cell belongs to Group A(1)/ or not (0)

Third bit

0

0

SET(1)/NULL(0) for Group B

0

cell belongs to Group B(1)/ or not (0)

Fourth bit

0

0

0

equipment is uncontrolled(0)/ controlled(1)

equipment is uncontrolled(0)/ controlled(1)

Table 11.1 Virtual Path/Virtual Channel Terminology Virtual Channel (VC)

A generic term used to describe unidirectional transport of ATM cells associated by a common unique identifier value.

Virtual Channel Link

A means of unidirectional transport of ATM cells between a point where a VCI value is assigned and the point where that value is translated or terminated.

Virtual Channel Identifier (VCI)

A unique numerical tag that identifies a particular VC link for a given VPC.

Virtual Channel Connection (VCC)

A concatenation of VC links that extends between two points where ATM service users access the ATM layer. VCCs are provided for the purpose of user-user, user-network, or networknetwork information transfer. Cell sequence integrity is preserved for cells belonging to the same VCC.

Virtual Path

A generic term used to describe unidirectional transport of ATM cells belonging to virtual channels that are associated by a common unique identifier value.

Virtual Path Link

A group of VC links, identified by a common value of VPI, between a point where a VPI value is assigned and the point where that value is translated or terminated.

Virtual Path Identifier (VPI) Identifies a particular VP link. Virtual Path Connection (VPC)

A concatenation of VP links that extends between the point where the VCI values are assigned and the point where those values are translated or removed, i.e., extending the length of a bundle of VC links that share the same VPI. VPCs are provided for the purpose of user-user, user-network, or network-network information transfer.

Table 11.2 Payload Type (PT) Field Coding

PT Coding

Interpretation

000

User data cell,

congestion not experienced,

SDU-type = 0

001

User data cell,

congestion not experienced,

SDU-type = 1

010

User data cell,

congestion experienced,

SDU-type = 0

011

User data cell,

congestion experienced,

SDU-type = 1

100

OAM segment associated cell

101

OAM end-to-end associated cell

110

Resource management cell

111

Reserved for future function

SDU = Service Data Unit OAM = Operations, Administration, and Maintenance

Table 12.2 Example of Least-Cost Routing Algorithms (using Figure 12.1)

(a) Dijkstra'a Algorithm (s = 1) Iteration

T

L(2)

Path

L(3)

Path

L(4)

Path

L(5)

Path

L(6)

Path

1

{1}

2

1-2

5

1-3

1

1-4

∞

—

∞

—

2

{1, 4}

2

1-2

4

1-4-3

1

1-4

2

1-4-5

∞

—

3

{1, 2, 4}

2

1-2

4

1-4-3

1

1-4

2

1-4-5

∞

—

4

{1, 2, 4, 5}

2

1-2

3

1-4-5-3

1

1-4

2

1-4-5

4

1-4-5-6

5

{1, 2, 3, 4, 5}

2

1-2

3

1-4-5-3

1

1-4

2

1-4-5

4

1-4-5-6

6

{1, 2, 3, 4, 5, 6}

2

1-2

3

1-4-5-3

1

1-4

2

1-4-5

4

1-4-5-6

(b) Bellman-Ford Algorithm (s = 1) h

Lh(2)

Path

Lh(3)

Path

Lh(4)

Path

Lh(5)

Path

Lh(6)

Path

0

∞

—

∞

—

∞

—

∞

—

∞

—

1

2

1-2

5

1-3

1

1-4

∞

—

∞

—

2

2

1-2

4

1-4-3

1

1-4

2

1-4-5

10

1- 3 - 6

3

2

1-2

3

1-4-5-3

1

1-4

2

1-4-5

4

1-4-5-6

4

2

1-2

3

1-4-5-3

1

1-4

2

1-4-5

4

1-4-5-6

Table 12.1 Elements of Routing Techniques for Packet-Switching Networks

Performance Criteria Number of hops Cost Delay Throughput Decision Time Packet (datagram) Session (virtual circuit) Decision Place Each node (distributed) Central node (centralized) Originating node (source)

Network Information Source None Local Adjacent node Nodes along route All nodes Network Information Update Timing Continuous Periodic Major load change Topology change

Table 13.1 Frame Relay Congestion Control Techniques

Technique

Type

Function

Key Elements

Discard control

Discard strategy

Backward explicit Congestion Notification

Congestion avoidance Provides guidance to BECN bit or CLLM end systems about message congestion in network

Forward explicit Congestion Notification

Congestion avoidance Provides guidance to FECN bit end systems about congestion in network

Implicit congestion notification

Congestion recovery

Provides guidance to network concerning which frames to discard

End system infers congestion from frame loss

DE bit

Sequence numbers in higher-layer PDU

Table13.2 Traffic Control and Congestion Control Functions

Response Time

Traffic Control Functions

Long Term

•Resource management using virtual paths

Connection Duration

•Connection admission control (CAC)

Round-Trip Propagation Time

•Fast resource management

Congestion Control Functions

•Explicit forward congestion indication (EFCI) •ABR flow control

Cell Insertion Time

•Usage parameter control (UPC) •Priority control •Traffic shaping

•Selective cell discard

Table 13.3 Traffic Parameters Used in Defining VCC/VPC Quality of Service

Parameter

Description

Traffic Type

Peak Cell Rate (PCR)

An upper bound on the traffic that can be submitted on an ATM connection.

CBR, VBR

Cell Delay Variation (CDV)

An upper bound on the variability in the pattern of cell arrivals observed at a single measurement point with reference to the peak cell rate.

CBR, VBR

Sustainable Cell Rate (SCR)

An upper bound on the average rate of an ATM connection, calculated over the duration of the connection.

VBR

Burst Tolerance

An upper bound on the variability in the pattern of cell arrivals observed at a single measurement point with reference to the sustainable cell rate.

VBR

CBR = constant bit rate VBR = variable bit rate

Table 13.4 Procedures Used to Set Values of Traffic Contract Parameters

Explicitly Specified Parameters Parameter Values Set at Connection-Setup Time

Parameter Values Specified at Subscription Time

Requested by User/NMS

Implicitly Specified Parameters Parameter Values Set Using Default Rules

Assigned by Network Operator

SVC

signaling

by subscription

network-operator default rules

PVC

NMS

by subscription

network-operator default rules

SVC = switched virtual connection PVC = permanent virtual connection NMS = network management system

Table 14.3 IS-95 Forward Link Channel Parameters Channel

Sync

Paging

Traffic Rate Set 1

Traffic Rate Set 2

Data rate (bps)

1200

4800

9600

1200

2400

4800

9600

1800

3600

7200

14400

Code repetition

2

2

1

8

4

2

1

8

4

2

1

Modulation symbol rate (sps)

4800

19,200

19,200

19,200

19,200

19,200

19,200

19,200

19,200

19,200

19,200

PN chips/ modulation symbol

256

64

64

64

64

64

64

64

64

64

64

PN chips/bit

1024

256

128

1024

512

256

128

682.67

341.33

170.67

85.33

Table 14.4 IS-95 Reverse Link Channel Parameters Channel Data rate (bps)

Access

Traffic-Rate Set 1

Traffic-Rate Set 2

4800

1200

2400

4800

9600

1800

3600

7200

14400

1/3

1/3

1/3

1/3

1/3

1/2

1/2

1/2

1/2

14,400

3600

7200

14,400

28,800

3600

7200

14,400

28,800

2

8

4

2

1

8

4

2

1

28,800

28,800

28,800

28,800

28,800

28,800

28,800

28,800

28,800

Transmit duty cycle

1

1/8

1/4

1/2

1

1/8

1/4

1/2

1

Code symbols/modulation symbol

6

6

6

6

6

6

6

6

6

PN chips/ modulation symbol

256

256

256

256

256

256

256

256

256

PN chips/bit

256

128

128

128

128

256/3

256/3

256/3

256/3

Code rate Symbol rate before repetition (sps) Symbol repetition Symbol rate after repetition (sps)

Table 14.1 Typical Parameters for Macrocells and Microcells [ANDE95] Macrocell

Microcell

Cell radius

1 to 20 km

0.1 to 1 km

Transmission power

1 to 10 W

0.1 to 1 W

Average delay spread

0.1 to 10 µs

10 to 100 ns

0.3 Mbps

1 Mbps

Maximum bit rate

Table 14.2 AMPS Parameters Base station transmission band

869 to 894 MHz

Mobile unit transmission band

824 to 849 MHz

Spacing between forward and reverse channels

45 MHz

Channel bandwidth

30 kHz

Number of full-duplex voice channels

790

Number of full-duplex control channels

42

Mobile unit maximum power

3 watts

Cell size, radius

2 to 20 km

Modulation, voice channel

FM, 12-kHz peak deviation

Modulation, control channel

FSK, 8-kHz peak deviation

Data transmission rate

10 kbps

Error control coding

BCH (48, 36,5) and (40, 28,5)

Table 14.5 W-CDMA Parameters Channel bandwidth

5 MHz

Forward RF channel structure

Direct spread

Chip rate

3.84 Mcps

Frame length

10 ms

Number of slots/frame

15

Spreading modulation

Balanced QPSK (forward) Dual channel QPSK (reverse) Complex spreading circuit

Data modulation

QPSK (forward) BPSK (reverse)

Coherent detection

Pilot symbols

Reverse channel multiplexing

Control and pilot channel time multiplexed. I and Q multiplexing for data and control channels

Multirate

Various spreading and multicode

Spreading factors

4 t0 256

Power control

Open and fast closed loop (1.6 kHz)

Spreading (forward)

Variable length orthogonal sequences for channel separation. Gold sequences 218 for cell and user separation.

Spreading (reverse)

Same as forward, different time shifts in I and Q channels.

Table 16.1 Characteristics of Some High-Speed LANs

Fast Ethernet

Gigabit Ethernet

Fibre Channel

Wireless LAN

100 Mbps

1 Gbps, 10 Gbps

100 Mbps - 3.2 Gbps

1 Mbps - 54 Mbps

UTP, STP, optical Fiber

UTP, shielded cable, optical fiber

Optical fiber, coaxial cable, STP

2.4-GHz, 5-GHz microwave

Access Method

CSMA/CD

Switched

Switched

CSMA/Polling

Supporting Standard

IEEE 802.3

IEEE 802.3

Fibre Channel Association

IEEE 802.11

Data Rate Transmission Media

Table 16.2 IEEE 802.3 10-Mbps Physical Layer Medium Alternatives

10BASE5

10BASE2

10BASE-T

10BASE-FP

Transmission medium

Coaxial cable (50 ohm)

Coaxial cable (50 ohm)

Unshielded twisted pair

850-nm optical fiber pair

Signaling technique

Baseband (Manchester)

Baseband (Manchester)

Baseband (Manchester)

Manchester/on-off

Topology

Bus

Bus

Star

Star

Maximum segment 500 length (m)

185

100

500

Nodes per segment 100

30

—

33

5

0.4 to 0.6

62.5/125 µm

Cable diameter (mm)

10

Table 17.1 IEEE 802.11 Standards Standard

Scope Medium access control (MAC): One common MAC for WLAN applications

IEEE 802.11

Physical layer: Infrared at 1 and 2 Mbps Physical layer: 2.4-GHz FHSS at 1 and 2 Mbps Physical layer: 2.4-GHz DSSS at 1 and 2 Mbps

IEEE 802.11a

Physical layer: 5-GHz OFDM at rates from 6 to 54 Mbps

IEEE 802.11b

Physical layer: 2.4-GHz DSSS at 5.5 and 11 Mbps

IEEE 802.11c

Bridge operation at 802.11 MAC layer

IEEE 802.11d

Physical layer: Extend operation of 802.11 WLANs to new regulatory domains (countries)

IEEE 802.11e

MAC: Enhance to improve quality of service and enhance security mechanisms

IEEE 802.11f

Recommended practices for multivendor access point interoperability

IEEE 802.11g

Physical layer: Extend 802.11b to data rates >20 Mbps

IEEE 802.11h

Physical/MAC: Enhance IEEE 802.11a to add indoor and outdoor channel selection and to improve spectrum and transmit power management

IEEE 802.11i

MAC: Enhance security and authentication mechanisms

IEEE 802.11j

Physical: Enhance IEEE 802.11a to conform to Japanese requirements

IEEE 802.11k

Radio resource measurement enhancements to provide interface to higher layers for radio and network measurements

IEEE 802.11m

Maintenance of IEEE 802.11-1999 standard with technical and editorial corrections

IEEE 802.11n

Physical/MAC: Enhancements to enable higher throughput

IEEE 802.11p

Physical/MAC: Wireless access in vehicular environments

IEEE 802.11r

Physical/MAC: Fast roaming (fast BSS transition)

IEEE 802.11s

Physical/MAC: ESS mesh networking

IEEE 802.11,2

Recommended practice for the Evaluation of 802.11 wireless performance

IEEE 802.11u

Physical/MAC: Interworking with external networks

Table 17.2 IEEE 802.11 Terminology Access point (AP)

Any entity that has station functionality and provides access to the distribution system via the wireless medium for associated stations

Basic service set (BSS)

A set of stations controlled by a single coordination function

Coordination function

The logical function that determines when a station operating within a BSS is permitted to transmit and may be able to receive PDUs

Distribution system (DS)

A system used to interconnect a set of BSSs and integrated LANs to create an ESS

Extended service set (ESS)

A set of one or more interconnected BSSs and integrated LANs that appear as a single BSS to the LLC layer at any station associated with one of these BSSs

MAC protocol data unit (MPDU)

The unit of data exchanged between two peer MAC entites using the services of the physical layer

MAC service data unit (MSDU)

Information that is delivered as a unit between MAC users

Station

Any device that contains an IEEE 802.11 conformant MAC and physical layer

Table 17.3 IEEE 802.11 Services Service

Provider

Used to support

Association

Distribution system

MSDU delivery

Authentication

Station

LAN access and security

Deauthentication

Station

LAN access and security

Dissassociation

Distribution system

MSDU delivery

Distribution

Distribution system

MSDU delivery

Integration

Distribution system

MSDU delivery

MSDU delivery

Station

MSDU delivery

Privacy

Station

LAN access and security

Reassocation

Distribution system

MSDU delivery

Table 17.4 IEEE 802.11 Physical Layer Standards

Available bandwidth Unlicensed frequency of operation

802.11

802.11a

802.11b

802.11g

83.5 MHz

300 MHz

83.5 MHz

83.5 MHz

2.4 - 2.4835 GHz

5.15 - 5.35 GHz OFDM

2.4 - 2.4835 GHz

2.4 - 2.4835 GHz

DSSS

DSSS, OFDM

3 (indoor/outdoor)

3 (indoor/outdoor)

DSSS, FHSS

5.725 - 5.825 GHz OFDM 4 indoor

Number of nonoverlapping channels

3 (indoor/outdoor)

Data rate per channel

1, 2 Mbps

6, 9, 12, 18, 24, 36, 48, 54 Mbps

1, 2, 5.5, 11 Mbps

1, 2, 5.5, 6, 9, 11, 12, 18, 24, 36, 48, 54 Mbps

Compatibility

802.11

Wi-Fi5

Wi-Fi

Wi-Fi at 11 Mbps and below

4 (indoor/outdoor) 4 outdoor

Table 17.5 Estimated Distance (m) Versus Data Rate Data Rate (Mbps)

802.11b

802.11a

802.11g

1

90+

—

90+

2

75

—

75

5.5(b)/6(a/g)

60

60+

65

9

—

50

55

11(b)/12(a/g)

50

45

50

18

—

40

50

24

—

30

45

36

—

25

35

48

—

15

25

54

—

10

20

Table 18.1

Addressing Modes

Destination

Network Address

System Address

Port/SAP Address

Unicast

Individual

Individual

Individual

Individual

Individual

Group

Individual

All

Group

All

All

Group

Individual

Individual

All

Individual

All

All

All

All

All

Multicast

Broadcast

Table 18.3 IP Addresses and Subnet Masks [STEI95] (a) Dotted decimal and binary representations of IP address and subnet masks

Binary Representation

Dotted Decimal

IP address

11000000.11100100.00010001.00111001

192.228.17.57

Subnet mask

11111111.11111111.11111111.11100000

255.255.255.224

Bitwise AND of address and mask (resultant network/subnet number)

11000000.11100100.00010001.00100000

192.228.17.32

Subnet number

11000000.11100100.00010001.001

1

Host number

00000000.00000000.00000000.00011001

25

(b) Default subnet masks

Binary Representation

Dotted Decimal

Class A default mask

11111111.00000000.00000000.00000000

255.0.0.0

Example Class A mask

11111111.11000000.00000000.00000000

255.192.0.0

Class B default mask

11111111.11111111.00000000.00000000

255.255.0.0

Example Class B mask

11111111.11111111.11111000.00000000

255.255.248.0

Class C default mask

11111111.11111111.11111111.00000000

255. 255. 255.0

Example Class C mask

11111111.11111111.11111111.11111100

255. 255. 255.252

Table 18.2 Internetworking Terms Communication Network A facility that provides a data transfer service among devices attached to the network. Internet A collection of communication networks interconnected by bridges and/or routers. Intranet An internet used by a single organization that provides the key Internet applications, especially the World Wide Web. An intranet operates within the organization for internal purposes and can exist as an isolated, self-contained internet, or may have links to the Internet. Subnetwork Refers to a constituent network of an internet. This avoids ambiguity because the entire internet, from a user's point of view, is a single network. End System (ES) A device attached to one of the networks of an internet that is used to support end-user applications or services. Intermediate System (IS) A device used to connect two networks and permit communication between end systems attached to different networks. Bridge An IS used to connect two LANs that use similar LAN protocols. The bridge acts as an address filter, picking up packets from one LAN that are intended for a destination on another LAN and passing those packets on. The bridge does not modify the contents of the packets and does not add anything to the packet. The bridge operates at layer 2 of the OSI model. Router An IS used to connect two networks that may or may not be similar. The router employs an internet protocol present in each router and each end system of the network. The router operates at layer 3 of the OSI model.

Table 19.1 Traffic Generated by Various Multicasting Strategies

(a) Broadcast N1

(b) Multiple Unicast

(c) Multicast

S → N2

S → N3

S → N5

S → N6

Total

S → N3

S → N5

S → N6

Total

1

1

1

1

4

1

1

1

3

1

1

1

1

1

2

2

1

1

1

1

1

1

N2 N3

1

N4

1

N5

1

N6 L1

1 1

1

2

1

1

1

1

1 1

1

L2 L3

1

L4

1 1

1

2

4

4

13

1 1

1

2

1

4

4

11

8

L5 Total

2

3

3

Table 19.2 BGP-4 Messages

Open

Used to open a neighbor relationship with another router.

Update

Used to (1) transmit information about a single route and/or (2) list multiple routes to be withdrawn.

Keepalive

Used to (1) acknowledge an Open message and (2) periodically confirm the neighbor relationship.

Notification

Send when an error condition is detected.

Table 19.3 Routing Table for R6

Destination

Next Hop

Distance

N1

R3

10

N2

R3

10

N3

R3

7

N4

R3

8

N6

R10

8

N7

R10

12

N8

R10

10

N9

R10

11

N10

R10

13

N11

R10

14

H1

R10

21

R5

R5

6

R7

R10

8

N12

R10

10

N13

R5

14

N14

R5

14

N15

R10

17

Table 19.4 Terminology for Differentiated Services Behavior Aggregate

A set of packets with the same DS codepoint crossing a link in a particular direction.

Classifier

Selects packets based on the DS field (BA classifier) or on multiple fields within the packet header (MF classifier).

DS Boundary Node

A DS node that connects one DS domain to a node in another domain

DS Codepoint

A specified value of the 6-bit DSCP portion of the 8-bit DS field in the IP header.

DS Domain

A contiguous (connected) set of nodes, capable of implementing differentiated services, that operate with a common set of service provisioning policies and per-hop behavior definitions.

DS Interior Node

A DS node that is not a DS boundary node.

DS Node

A node that supports differentiated services. Typically, a DS node is a router. A host system that provides differentiated services for applications in the host is also a DS node.

Dropping

The process of discarding packets based on specified rules; also called policing.

Marking

The process of setting the DS codepoint in a packet. Packets may be marked on initiation and may be re-marked by an en route DS node.

Metering

The process of measuring the temporal properties (e.g., rate) of a packet stream selected by a classifier. The instantaneous state of that process may affect marking, shaping, and dropping functions.

Per-Hop Behavior (PHB)

The externally observable forwarding behavior applied at a node to a behavior aggregate.

Service Level Agreement (SLA)

A service contract between a customer and a service provider that specifies the forwarding service a customer should receive.

Shaping

The process of delaying packets within a packet stream to cause it to conform to some defined traffic profile.

Traffic Conditioning

Control functions performed to enforce rules specified in a TCA, including metering, marking, shaping, and dropping.

Traffic Conditioning Agreement (TCA)

An agreement specifying classifying rules and traffic conditioning rules that are to apply to packets selected by the classifier.

Table 19.5 IP Performance Metrics (a) Sampled metrics Metric Name

Singleton Definition

Statistical Definitions

One-Way Delay

Delay = dT, where Src transmits first bit of packet at T and Dst received last bit of packet at T + dT

Percentile, median, minimum, inverse percentile

Round-Trip Delay

Delay = dT, where Src transmits first bit of packet at T and Src received last bit of packet immediately returned by Dst at T + dT

Percentile, median, minimum, inverse percentile

One-Way Loss

Packet loss = 0 (signifying successful transmission and reception of packet); = 1 (signifying packet loss)

Average

One-Way Loss Pattern

Loss distance: Pattern showing the distance between successive packet losses in terms of the sequence of packets

Number or rate of loss distances below a defined threshold, number of loss periods, pattern of period lengths, pattern of inter-loss period lengths.

Loss period: Pattern showing the number of bursty losses (losses involving consecutive packets) Packet Delay Variation

Packet delay variation (pdv) for a pair of packets with a stream of packets = difference between the one-way-delay of the selected packets

Percentile, inverse percentile, jitter, peak-topeak pdv

Src = IP address of a host Dst = IP address of a host (b) Other metrics Metric Name

General Definition

Metrics

Connectivity

Ability to deliver a packet over a transport connection.

One-way instantaneous connectivity, Two-way instantaneous connectivity, one-way interval connectivity, two-way interval connectivity, two-way temporal connectivity

Bulk Transfer Capacity

Long-term average data rate (bps) over a single congestion-aware transport connection.

BTC = (data sent)/(elapsed time)

Table 20.1 Transport Protocol Timers

Retransmission timer

Retransmit an unacknowledged segment

2MSL (maximum segment lifetime) timer

Minimum time between closing one connection and opening another with the same destination address

Persist timer

Maximum time between ACK/CREDIT segments

Retransmit-SYN timer

Time between attempts to open a connection

Keepalive timer

Abort connection when no segments are received

Table 20.2 TCP Service Request Primitives

Primitive

Parameters

Description

Unspecified Passive Open

source-port, [timeout], [timeoutaction], [precedence], [securityrange]

Listen for connection attempt at specified security and precedence from any remote destination.

Fully Specified Passive Open

source-port, destination-port, destination-address, [timeout], [timeout-action], [precedence], [security-range]

Listen for connection attempt at specified security and precedence from specified destination.

Active Open

source-port, destination-port, destination-address, [timeout], [timeout-action], [precedence], [security]

Request connection at a particular security and precedence to a specified destination.

Active Open with Data

source-port, destination-port, destination-address, [timeout], [timeout-action], [precedence], [security], data, data-length, PUSHflag, URGENT-flag

Request connection at a particular security and precedence to a specified destination and transmit data with the request.

Send

local-connection-name, data, datalength, PUSH-flag, URGENT-flag, [timeout], [timeout-action]

Transfer data across named connection.

Allocate

local-connection-name, data-length

Issue incremental allocation for receive data to TCP.

Close

local-connection-name

Close connection gracefully.

Abort

local-connection-name

Close connection abruptly.

Status

local-connection-name

Query connection status.

Note: Square brackets indicate optional parameters.

Table 20.3

Primitive

TCP Service Response Primitives

Parameters

Description

Open ID

local-connection-name, source-port, destination-port*, destination-address*,

Informs TCP user of connection name assigned to pending connection requested in an Open primitive

Open Failure

local-connection-name

Reports failure of an Active Open request

Open Success local-connection-name

Reports completion of pending Open request

Deliver

local-connection-name, data, data-length, URGENT-flag

Reports arrival of data

Closing

local-connection-name

Reports that remote TCP user has issued a Close and that all data sent by remote user has been delivered

Terminate

local-connection-name, description

Reports that the connection has been terminated; a description of the reason for termination is provided

Status Response

local-connection-name, source-port, source-address, destination-port, destination-address, connection-state, receive-window, send-window, amountawaiting-ACK, amount-awaiting-receipt, urgent-state, precedence, security, timeout

Reports current status of connection

Error

local-connection-name, description

Reports service-request or internal error

* = Not used for Unspecified Passive Open.

Table 20.4 TCP Service Parameters Source Port

Local TCP user

Timeout

Longest delay allowed for data delivery before automatic connection termination or error report; user specified

Timeout-action

Indicates whether the connection is terminated or an error is reported to the TCP user in the event of a timeout

Precedence

Precedence level for a connection. Takes on values zero (lowest) through seven (highest); same parameter as defined for IP

Security-range

Allowed ranges in compartment, handling restrictions, transmission control codes, and security levels

Destination Port

Remote TCP user

Destination Address

Internet address of remote host

Security

Security information for a connection, including security level, compartment, handling restrictions, and transmission control code.; same parameter as defined for IP

Data

Block of data sent by TCP user or delivered to a TCP user

Data Length

Length of block of data sent or delivered

PUSH flag

If set, indicates that the associated data are to be provided with the data stream push service

URGENT flag

If set, indicates that the associated data are to be provided with the urgent data signaling service

Local Connection Name

Identifier of a connection defined by a (local socket, remote socket) pair; provided by TCP

Description

Supplementary information in a Terminate or Error primitive

Source Address

Internet address of the local host

Connection State

State of referenced connection (CLOSED, ACTIVE OPEN, PASSIVE OPEN, ESTABLISHED, CLOSING)

Receive Window

Amount of data in octets the local TCP entity is willing to receive

Send Window

Amount of data in octets permitted to be sent to remote TCP entity

Amount Awaiting ACK

Amount of previously transmitted data awaiting acknowledgment

Amount Awaiting Receipt

Amount of data in octets buffered at local TCP entity pending receipt by local TCP user

Urgent State

Indicates to the receiving TCP user whether there are urgent data available or whether all urgent data, if any, have been delivered to the user

Table 20.5 Implementation of TCP Congestion Control Measures

Measure

RFC 1122

TCP Tahoe

TCP Reno

NewReno

RTT Variance Estimation

✓

✓

✓

✓

Exponential RTO Backoff

✓

✓

✓

✓

Karn's Algorithm

✓

✓

✓

✓

Slow Start

✓

✓

✓

✓

Dynamic Window Sizing on Congestion

✓

✓

✓

✓

✓

✓

✓

✓

✓

Fast Retransmit Fast Recovery Modified Fast Recovery

✓

Table 21.1 Average Time Required for Exhaustive Key Search

Key Size (bits)

Number of Alternative Keys

Time Required at 1 Decryption/µs

Time Required at 106 Decryptions/µs

32

232 = 4.3 × 109

231 µs = 35.8 minutes

56

256 = 7.2 × 1016

255 µs = 1142 years

128

2128 = 3.4 × 1038

2127 µs = 5.4 × 1024 years

5.4 × 1018 years

168

2168 = 3.7 × 1050

2167 µs = 5.9 × 1036 years

5.9 × 1030 years

26 characters (permutation)

26! = 4 × 1026

2 × 1026 µs = 6.4 × 1012 years

2.15 milliseconds 10.01 hours

6.4 × 106 years

Table 22.1 SMTP Commands

Name

Command Form

Description

HELO

HELO

Send identification

MAIL

MAIL FROM:

Identifies originator of mail

RCPT

RCPT TO:

Identifies recipient of mail

DATA

DATA

Transfer message text

RSET

RSET

Abort current mail transaction

NOOP

NOOP

No operation

QUIT

QUIT

Close TCP connection

SEND

SEND FROM:

Send mail to terminal

SOML

SOML FROM:

Send mail to terminal if possible; otherwise to mailbox

SAML

SAML FROM:

Send mail to terminal and mailbox

VRFY

VRFY

Confirm user name

EXPN

EXPN

Return membership of mailing list

HELP

HELP [ ]

Send system-specific documentation

TURN

TURN

Reverse role of sender and receiver

= carriage return, line feed = space Square brackets denote optional elements. Shaded commands are optional in a conformant SMTP implementation.

Table 22.3 MIME Content Types Type

Subtype

Description

Text

Plain

Unformatted text; may be ASCII or ISO 8859.

Multipart

Mixed

Digest

The different parts are independent but are to be transmitted together. They should be presented to the receiver in the order that they appear in the mail message. Differs from Mixed only in that no order is defined for delivering the parts to the receiver. The different parts are alternative versions of the same information. They are ordered in increasing faithfulness to the original and the recipient's mail system should display the "best" version to the user. Similar to Mixed, but the default type/subtype of each part is message/rfc822

Message

rfc822 Partial External-body

The body is itself an encapsulated message that conforms to RFC 822. Used to allow fragmentation of large mail items, in a way that is transparent to the recipient. Contains a pointer to an object that exists elsewhere.

Image

jpeg gif

The image is in JPEG format, JFIF encoding. The image is in GIF format.

Video

mpeg

MPEG format.

Audio

Basic

Single-channel 8-bit ISDN mu-law encoding at a sample rate of 8 kHz.

Application

PostScript octet-stream

Adobe Postscript General binary data consisting of 8-bit bytes.

Parallel Alternative

Table 22.2 SMTP Replies Code

Description

220 221 250 251

Positive Completion Reply System status, or system help reply Help message (Information on how to use the receiver or the meaning of a particular non-standard command; this reply is useful only to the human user) Service ready Service closing transmission channel Requested mail action okay, completed User not local; will forward to

354

Positive Intermediate Reply Start mail input; end with .

211 214

421 450 451 452 500 501 502 503 504 550 551 552 553 554

Transient Negative Completion Reply Service not available, losing transmission channel (This may be a reply to any command if the service knows it must shut down) Requested mail action not taken: mailbox unavailable (e.g., mailbox busy) Requested action aborted: local error in processing Requested action not taken: insufficient system storage Permanent Negative Completion Reply Syntax error, command unrecognized (This may include errors such as command line too long) Syntax error in parameters or arguments Command not implemented Bad sequence of commands Command parameter not implemented Requested action not taken: mailbox unavailable (e.g., mailbox not found, no access) User not local; please try Requested mail action aborted: exceeded storage allocation Requested action not taken: mailbox name not allowed (e.g., mailbox syntax incorrect) Transaction failed

Table 22.4 MIME Transfer Encodings

7bit

The data are all represented by short lines of ASCII characters.

8bit

The lines are short, but there may be non-ASCII characters (octets with the high-order bit set).

binary

Not only may non-ASCII characters be present but the lines are not necessarily short enough for SMTP transport.

quoted-printable

Encodes the data in such a way that if the data being encoded are mostly ASCII text, the encoded form of the data remains largely recognizable by humans.

base64

Encodes data by mapping 6-bit blocks of input to 8-bit blocks of output, all of which are printable ASCII characters.

x-token

A named nonstandard encoding.

Table 22.5 Radix-64 Encoding

6-Bit Value

Character Encoding

6-Bit Value

Character Encoding

6-Bit Value

Character Encoding

6-Bit Value

Character Encoding

0

A

16

Q

32

g

48

w

1

B

17

R

33

h

49

x

2

C

18

S

34

i

50

y

3

D

19

T

35

j

51

z

4

E

20

U

36

k

52

0

5

F

21

V

37

l

53

1

6

G

22

W

38

m

54

2

7

H

23

X

39

n

55

3

8

I

24

Y

40

o

56

4

9

J

25

Z

41

p

57

5

10

K

26

a

42

q

58

6

11

L

27

b

43

r

59

7

12

M

28

c

44

s

60

8

13

N

29

d

45

t

61

9

14

O

30

e

46

u

62

+

15

P

31

f

47

v

63

/

(pad)

=

TABLE 22.6 Allowable Data Types in SNMPv2 Data Type

Description

INTEGER

Integers in the range of –231 to 231 – 1.

UInteger32

Integers in the range of 0 to 232 – 1.

Counter32

A nonnegative integer that may be incremented modulo 232.

Counter64

A nonnegative integer that may be incremented modulo 264.

Gauge32

A nonnegative integer that may increase or decrease, but shall not exceed a maximum value. The maximum value can not be greater than 232 – 1.

TimeTicks

A nonnegative integer that represents the time, modulo 232, in hundredths of a second.

OCTET STRING

Octet strings for arbitrary binary or textual data; may be limited to 255 octets.

IpAddress

A 32-bit internet address.

Opaque

An arbitrary bit field.

BIT STRING

An enumeration of named bits.

OBJECT IDENTIFIER

Administratively assigned name to object or other standardized element. Value is a sequence of up to 128 nonnegative integers.

Table 23.1 Top-Level Internet Domains Domain

Contents

com

Commercial organizations

edu

Educational institutions

gov

U.S. federal government agencies

mil

U.S. military

net

Network support centers, Internet service providers, and other network-related organizations

org

Nonprofit organizations

us

U.S. state and local government agencies, schools, libraries, and museums

country code

ISO standard 2-letter identifier for country-specific domains (e.g., au, ca, uk)

biz

Dedicated exclusively for private businesses

info

Unrestricted use

name

Individuals, for email addresses and personalized domain names.

museum

restricted to museums, museum organizations, and individual members of the museum profession

coop

Member-owned cooperative organizations, such as credit unions

aero

Aviation community

pro

Medical, legal, and accounting professions

arpa

Temporary ARPA domain (still used)

int

International organizations

Table 23.2 Resource Record Types Type

Description

A

A host address. This RR type maps the name of a system to its IP address. Some systems (e.g., routers) have multiple addresses, and there is a separate RR for each.

CNAME

Canonical name. Specifies an alias name for a host and maps this to the canonical (true) name.

HINFO

Host information. Designates the processor and operating system used by the host.

MINFO

Mailbox or mail list information. Maps a mailbox or mail list name to a host name.

MX

Mail exchange. Identifies the systems that relay mail into the organization.

NS

Authoritative name server for this domain.

PTR

Domain name pointer. Points to another part of the domain name space.

SOA

Start of a zone of authority (which part of naming hierarchy is implemented). Includes parameters related to this zone.

SRV

For a given service provides name of server or servers in domain that provide that service.

TXT

Arbitrary text. Provides a way to add text comments to the database.

WKS

Well-known services. May list the application services available at this host.

Table 23.3 Internet Root Servers Server

Operator

Cities

IP Addr

A

VeriSign Global Registry Services

Herndon VA, US

198.41.0.4

B

Information Sciences Institute

Marina Del Rey CA, US

128.9.0.107

C

Cogent Communications

Herndon VA, US

192.33.4.12

D

University of Maryland

College Park MD, US

128.8.10.90

E

NASA Ames Research Center

Mountain View CA, US

192.203.230.10

F

Internet Software Consortium

Palo Alto CA, US;

IPv4: 192.5.5.241

San Francisco CA, US IPv6: 2001:500::1035 G

U.S. DOD Network Information Center

Vienna VA, US

192.112.36.4

H

U.S. Army Research Lab

Aberdeen MD, US

128.63.2.53

I

Autonomica

Stockholm, SE

192.36.148.17

J

VeriSign Global Registry Services

Herndon VA, US

192.58.128.30

K

Reseaux IP Europeens - Network Coordination Centre

London, UK

193.0.14.129

L

Internet Corporation for Assigned Names and Numbers

Los Angeles CA, US

198.32.64.12

M

WIDE Project

Tokyo, JP

202.12.27.33

Table 23.4 Key Terms Related to HTTP Cache A program's local store of response messages and the subsystem that controls its message storage, retrieval, and deletion. A cache stores cacheable responses in order to reduce the response time and network bandwidth consumption on future, equivalent requests. Any client or server may include a cache, though a cache cannot be used by a server while it is acting as a tunnel. Client An application program that establishes connections for the purpose of sending requests. Connection A transport layer virtual circuit established between two application programs for the purposes of communication. Entity A particular representation or rendition of a data resource, or reply from a service resource, that may be enclosed within a request or response message. An entity consists of entity headers and an entity body.

Origin Server The server on which a given resource resides or is to be created. Proxy An intermediary program that acts as both a server and a client for the purpose of making requests on behalf of other clients. Requests are serviced internally or by passing them, with possible translation, on to other servers. A proxy must interpret and, if necessary, rewrite a request message before forwarding it. Proxies are often used as client-side portals through network firewalls and as helper applications for handling requests via protocols not implemented by the user agent. Resource A network data object or service which can be identified by a URI. Server An application program that accepts connections in order to service requests by sending back responses.

Gateway A server that acts as an intermediary for some other server. Unlike a proxy, a gateway receives requests as if it were the original server for the requested resource; the requesting client may not be aware that it is communicating with a gateway. Gateways are often used as server-side portals through network firewalls and as protocol translators for access to resources stored on non-HTTP systems.

Tunnel An intermediary program that is acting as a blind relay between two connections. Once active, a tunnel is not considered a party to the HTTP communication, though the tunnel may have been initiated by an HTTP request. A tunnel ceases to exist when both ends of the relayed connections are closed. Tunnels are used when a portal is necessary and the intermediary cannot, or should not, interpret the relayed communication.

Message The basic unit of HTTP communication, consisting of a structured sequence of octets transmitted via the connection.

User Agent The client that initiates a request. These are often browsers, editors, spiders, or other enduser tools.

Table 23.5 Augmented BNF Notation Used in URL and HTTP Specifications

•Words in lowercase represent variables or names of rules. •A rule has the form name = definition •DIGIT is any decimal digit; CRLF is carriage return, line feed; SP is one or more spaces. •Quotation marks enclose literal text. •Angle brackets, "<" ">", may be used within a definition to enclose a rule name when their presence will facilitate clarity. •Elements separated by bar ("|") are alternatives. •Ordinary parentheses are used simply for grouping. •The character "*" preceding an element indicates repetition. The full form is: *element indicating at least I and at most J occurrences of element. *element allows any number, including 0; 1*element requires at least one element; and 1*2element allows 1 or 2 elements; element means exactly N elements. •Square brackets, "[" "]", enclose optional elements. •The construct "#" is used to define, with the following form: #element indicating at least I and at most J elements, each separated by a comma and optional linear white space. •A semicolon at the right of a rule starts a comment that continues to the end of the line.

Table 24.1 Prediction Modes for Macroblock in B Picture

Mode

Predictor

Forward predicted

ˆI (z ) = ˆI (z + M ) 1 0 01

Backward predicted

ˆI (z ) = ˆI (z + M ) 1 2 21

Average

ˆ ˆ ˆI (z ) = I 0 (z + M01 ) + I 2 (z + M21 ) 1 2

Note: z = the vector (x, y).

Table 24.2 Payload Types for Standard Audio and Video Encodings (RFC 1890)

0

PCMU audio

16-23

unassigned audio

1

1016 audio

24

unassigned video

2

G721 audio

25

CelB video

3

GSM audio

26

JPEG video

4

unassigned audio

27

unassigned

5

DV14 audio (8 kHz)

28

nv video

6

DV14 audio (16 kHz)

29-30

unassigned video

7

LPC audio

31

H261 video

8

PCMA audio

32

MPV video

9

G722 audio

33

MP2T video

10

L16 audio (stereo)

34-71

unassigned

11

L16 audio (mono)

72-76

reserved

12-13

unassigned audio

77-95

unassigned

14

MPA audio

96-127

dynamic

15

G728 audio

Table 24.3 SDES Types (RFC 1889) Value

Name

Description

0

END

End of SDES list

1

CNAME

Canonical name: unique among all participants within one RTP session

2

NAME

Real user name of the source

3

EMAIL

E-mail address

4

PHONE

Telephone number

5

LOC

Geographic location

6

TOOL

Name of application generating the stream

7

NOTE

Transient message describing the current state of the source

8

PRIV

Private experimental or application-specific extensions