figure 3.1 network types - cdk3: home page lan 0.15–1.5 km 2–11 5–20 wireless wan worldwide...

Instructor’s Guide for

Coulouris, Dollimore and Kindberg

Distributed Systems: Concepts and Design

Edn. 3 © Pearson Education 2001 1

Figure 3.1 Network types

Range Bandwidth (Mbps) Latency (ms)

LAN 1–2 kms 10–1000 1–10

WAN worldwide 0.010–600 100–500

MAN 2–50 kms 1–150 10

Wireless LAN 0.15–1.5 km 2–11 5–20

Wireless WAN worldwide 0.010–2 100-500

Internet worldwide 0.010–2 100–500





Figure 3.2 Conceptual layering of protocol software

Layer n

Layer 2

Layer 1

Message sent Message received

Communicationmedium

Sender Recipient

•

•





Figure 3.3 Encapsulation as it is applied in layered protocols

Application-layer message

Presentation header

Session header

Transport header

Network header





Figure 3.4 Protocol layers in the ISO Open Systems Interconnection (OSI) protocol model

Application

Presentation

Session

Transport

Network

Data link

Physical

Message sent Message received

Sender Recipient

Layers

Communicationmedium





Figure 3.5 OSI protocol summary

Layer Description Examples

Application Protocols that are designed to meet the communication requirements of specific applications, often defining the interface to a service.

HTTP, FTP, SMTP, CORBA IIOP

Presentation Protocols at this level transmit data in a network representation that is independent of the representations used in individual computers, which may differ. Encryption is also performed in this layer, if required.

Secure Sockets (SSL),CORBA Data Rep.

Session At this level reliability and adaptation are performed, such as detection of failures and automatic recovery.

Transport This is the lowest level at which messages (rather than packets) are handled. Messages are addressed to communication ports attached to processes, Protocols in this layer may be connection-oriented or connectionless.

TCP, UDP

Network Transfers data packets between computers in a specific network. In a WAN or an internetwork this involves the generation of a route passing through routers. In a single LAN no routing is required.

IP, ATM virtual circuits

Data link Responsible for transmission of packets between nodes that are directly connected by a physical link. In a WAN transmission is between pairs of routers or between routers and hosts. In a LAN it is between any pair of hosts.

Ethernet MAC, ATM cell transfer, PPP

Physical The circuits and hardware that drive the network. It transmits sequences of binary data by analogue signalling, using amplitude or frequency modulation of electrical signals (on cable circuits), light signals (on fibre optic circuits) or other electromagnetic signals (on radio and microwave circuits).

Ethernet base-band signalling, ISDN





Figure 3.6 Internetwork layers

Underlying network

Application

Network interface

Transport

Internetwork

Internetwork packets

Network-specific packets

MessageLayers

Internetworkprotocols

Underlyingnetworkprotocols





Figure 3.7 Routing in a wide area network

Hosts Linksor local networks

A

D E

B

C

12

5

43

6Routers





Figure 3.8 Routing tables for the network in Figure 3.7

Routings from A Routings from B Routings from C

To Link Cost To Link Cost To Link Cost

ABCDE

local1131

01212

ABCDE

1local

214

10121

ABCDE

22

local55

21021

Routings from D Routings from E

To Link Cost To Link Cost

ABCDE

336

local6

12201

ABCDE

4456

local

21110





Figure 3.9 Pseudo-code for RIP routing algorithm

Send: Each t seconds or when Tl changes, send Tl on each non-faulty outgoing link.

Receive: Whenever a routing table Tr is received on link n:for all rows Rr in Tr {

if (Rr.link ≠ n) {Rr.cost = Rr.cost + 1;Rr.link = n;if (Rr.destination is not in Tl) add Rr to Tl; // add new destination to Tlelse for all rows Rl in Tl {

if (Rr.destination = Rl.destination and (Rr.cost < Rl.cost or Rl.link = n)) Rl = Rr;// Rr.cost < Rl.cost : remote node has better route// Rl.link = n : remote node is more authoritative

}}

}





Figure 3.10 Simplified view of the QMW Computer Science network

file

compute

dialup

hammer

henry

hotpoint

138.37.88.230

138.37.88.162

bruno138.37.88.249

router/sickle

138.37.95.241138.37.95.240/29

138.37.95.249

138.

37.9

4.24

7

copper138.37.88.248

firewall

web

138.37.95.248/29

server

desktop computers 138.37.88.xx

subnet

subnet

Eswitch

138.37.88

server

server

server

138.37.88.251

custard138.37.94.246

desktop computers 138.37.94.xx

Eswitch

138.37.94

hubhub

Student subnetStaff subnet

otherservers

router/firewall

138.37.94.251

138.

37.8

8.24

7

☎

1000 Mbps EthernetEswitch: Ethernet switch

100 Mbps Ethernet

file server/gateway

printers

138.

37.9

5.23

2/29

subn

et

Campusrouter

Campusrouter





Figure 3.11 Tunnelling for IPv6 migration

A BIPv6 IPv6

IPv6 encapsulated in IPv4 packets

Encapsulators

IPv4 network





Figure 3.12 TCP/IP layers

Messages (UDP) or Streams (TCP)

Application

Transport

Internet

UDP or TCP packets

IP datagrams

Network-specific frames

MessageLayers

Underlying network

Network interface





Figure 3.13 Encapsulation as it occurs when a message is transmitted via TCP over an Ethernet

Application message

TCP header

IP header

Ethernet header

Ethernet frame

port

TCP

IP





Figure 3.14 The programmer's conceptual view of a TCP/IP Internet

IP

Application Application

TCP UDP





Figure 3.15 Internet address structure, showing field sizes in bits

7 24

Class A: 0 Network ID Host ID

14 16

Class B: 1 0 Network ID Host ID

21 8

Class C: 1 1 0 Network ID Host ID

28

Class D (multicast): 1 1 1 0 Multicast address

27

Class E (reserved): 1 1 1 1 unused0





Figure 3.16 Decimal representation of Internet addresses

octet 1 octet 2 octet 3

Class A: 1 to 127

0 to 255 0 to 255 1 to 254

Class B: 128 to 191

Class C: 192 to 223

224 to 239 Class D (multicast):

Network ID

Network ID

Network ID

Host ID

Host ID

Host ID

Multicast address

0 to 255 0 to 255 1 to 254

0 to 255 0 to 255 0 to 255

0 to 255 0 to 255 0 to 255

Multicast address

0 to 255 0 to 255 1 to 254240 to 255 Class E (reserved):

1.0.0.0 to 127.255.255.255

128.0.0.0 to 191.255.255.255

192.0.0.0 to 223.255.255.255

224.0.0.0 to 239.255.255.255

240.0.0.0 to 255.255.255.255

Range of addresses





Figure 3.17 IP packet layout

dataIP address of destinationIP address of source

header

up to 64 kilobytes





Figure 3.18 IPv6 header layout

Source address(128 bits)

Destination address(128 bits)

Version (4 bits) Priority (4 bits) Flow label (24 bits)Payload length (16 bits) Hop limit (8 bits)Next header (8 bits)





Sender

Home

Figure 3.19 The MobileIP routing mechanism

Mobile host MH

Foreign agent FAInternet

agent

First IP packet addressed to MH

Address of FAreturned to sender

First IP packettunnelled to FA

Subsequent IP packetstunnelled to FA





Figure 3.20 Firewall configurations

Internet

Router/Protected intraneta) Filtering router

Internet

b) Filtering router and bastion

filter

Internet

R/filterc) Screened subnet for bastion R/filter Bastion

R/filter Bastion

web/ftpserver

web/ftpserver

web/ftpserver





Figure 3.21 IEEE 802 network standards

IEEE No. Title Reference

802.3 CSMA/CD Networks (Ethernet) [IEEE 1985a]802.4 Token Bus Networks [IEEE 1985b]802.5 Token Ring Networks [IEEE 1985c]802.6 Metropolitan Area Networks [IEEE 1994]802.11 Wireless Local Area Networks [IEEE 1999]





Figure 3.22 Wireless LAN configuration

LAN

Server

WirelessLAN

Laptops

Base station/access point

Palmtop

radio obstruction

A B C

D E

Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3 © Pearson Education 2001 23

Figure 3.23 ATM protocol layers

Physical

Application

ATM layer

Higher-layer protocols

ATM cells

ATM virtual channels

MessageLayers

ATM adaption layer


Flags

Figure 3.24 ATM cell layout

DataVirtual channel idVirtual path id

53 bytes

Header: 5 bytes


Figure 3.25 Switching virtual paths in an ATM network

VPI in VPI out

23

45

VPI = 3

VPI = 5

VPI = 4

Virtual path Virtual channels

VPI = 2

VPI : virtual path identifier

VP switch VP/VCswitch

VP switch

Host

Host

figure 3.1 network types - cdk3: home page lan 0.15–1.5 km 2–11 5–20 wireless wan worldwide...

Documents