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Slides for Chapter 3:
Networking and Internetworking
From Coulouris, Dollimore and
Kindberg
Distributed Systems:
Concepts and Design
Edition 3, © Addison-Wesley 2001
Figure 3.1
Network types
Range
LAN
1-2 kms
WAN
worldwide
MAN
2-50 kms
Wireless LAN 0.15-1.5 km
Wireless WAN worldwide
Internet
worldwide
Bandwidth (Mbps) Latency (ms)
10-1000
0.010-600
1-150
2-11
0.010-2
0.010-2
1-10
100-500
10
5-20
100-500
100-500
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3
© Addison-Wesley Publishers 2000
Figure 3.2
Conceptual layering of protocol software
Message received
Message sent
Layer n
Layer 2
Layer 1
Sender
Communication
medium
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3
© Addison-Wesley Publishers 2000
Recipient
Figure 3.3
Encapsulation as it is applied in layered protocols
Applic ation-layer mess age
Pres entation header
Sess ion header
Transport header
Netw ork header
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3
© Addison-Wesley Publishers 2000
Figure 3.4
Protocol layers in the ISO Open Systems Interconnection (OSI) model
Mess age receiv ed
Mess age s ent
Lay ers
Applic ation
Pres entation
Sess ion
Transport
Netw ork
Data link
Phy sical
Sender
Communic ation
medium
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3
© Addison-Wesley Publishers 2000
Recipient
Figure 3.5
OSI protocol summary
Layer
Application
Presentation
Session
Transport
Network
Data link
Physical
Description
Protocols that are designed to meet the communication requirements of
specific applications, often defining the interface to a service.
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.
At this level reliability and adaptation are performed, such as detection of
failures and automatic recovery.
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.
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.
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.
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).
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3
© Addison-Wesley Publishers 2000
Examples
HTTP, FTP , SMTP,
CORBA IIOP
Secure Sockets
(SSL),CORBA Data
Rep.
TCP, UDP
IP, ATM virtual
circuits
Ethernet MAC,
ATM cell transfer,
PPP
Ethernet base- band
signalling, ISDN
Figure 3.6
Internetwork layers
Mess age
Lay ers
Applic ation
Internetw ork
protocols
Transport
Internetw ork
Internetw ork pac kets
Netw ork interface
Netw ork-spec ific packets
Underly ing netw ork
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3
© Addison-Wesley Publishers 2000
Underly ing
netw ork
protocols
Figure 3.7
Routing in a wide area network
A
Hosts
or local
networks
1
B
2
3
Links
4
C
5
D
6
E
Routers
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3
© Addison-Wesley Publishers 2000
Figure 3.8
Routing tables for the network in Figure 3.7
Routings from A
To
Link
Cost
A
local
0
B
1
1
C
1
2
D
3
1
E
1
2
Routings from B
To
Link
Cost
A
1
1
B
local
0
C
2
1
D
1
2
E
4
1
Routings from D
To
Link
Cost
A
3
1
B
3
2
C
6
2
D
local
0
E
6
1
Routings from C
To
Link
Cost
A
2
2
B
2
1
C
local
0
D
5
2
E
5
1
Routings from E
To
Link
Cost
A
4
2
B
4
1
C
5
1
D
6
1
E
local
0
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3
© Addison-Wesley Publishers 2000
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 Tl
else 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
}
}
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3
}
© Addison-Wesley Publishers 2000
Figure 3.10
Simplified view of the QMW Computer Science network
Campus138.37.95.240/29
router subnet
138.37.95.241
router/
firewall
hammer
Staff subnet
compute
server
Student subnet
138.37.88.251
138.37.88
138.37.94.251
Eswitch
Eswitch
bruno
138.37.88.249
%
138.37.94
file server/
gateway
custard
138.37.94.246
dialup
server
henry
138.37.88.230
printers
other
servers
file
server
hotpoint
138.37.88.162
web
server
copper
138.37.88.248
hub
hub
desktop computers138.37.88.xx
Campus138.37.95.248/29
subnet
router
desktop computers138.37.94.xx
sickle
router/
138.37.95.249 firewall
100 Mbps Ethernet
1000 Mbps Ethernet
Eswitch: Ethernet switch
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3
© Addison-Wesley Publishers 2000
Figure 3.11
Tunnelling for IPv6 migration
IPv6 encapsulated in IPv4 packets
IPv4 network
A
IPv6
IPv6
Encapsulators
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3
© Addison-Wesley Publishers 2000
B
Figure 3.12
TCP/IP layers
Message
Layers
Application
Messages (UDP) or Streams (TCP)
Transport
UDP or TCP packets
Internet
IP datagrams
Network interface
Network-specific frames
Underlying network
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3
© Addison-Wesley Publishers 2000
Figure 3.13
Encapsulation in a message transmitted via TCP over an Ethernet
Application message
TCP header
port
IP header TCP
Ethernet header IP
Ethernet frame
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3
© Addison-Wesley Publishers 2000
Figure 3.14
The programmer's conceptual view of a TCP/IP Internet
Applic ation
Applic ation
TCP
UDP
IP
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3
© Addison-Wesley Publishers 2000
Figure 3.15
Internet address structure, showing field sizes in bits
Clas s A:
Clas s B:
0
7
24
Netw ork ID
Host ID
1 0
14
16
Netw ork ID
Host ID
21
Clas s C:
1 1 0
8
Netw ork ID
Host ID
28
Clas s D (multicast ):
1 1 1 0
Multicast address
27
Clas s E (reserved):
1 1 1 1 0
unused
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3
© Addison-Wesley Publishers 2000
Figure 3.16
Decimal representation of Internet addresses
octet 1
octet 2
Network ID
Class A:
1 to 127
octet 3
Host ID
0 to 255
0 to 255
1.0.0.0 to
127.255.255.255
0 to 255
0 to 255
128.0.0.0 to
191.255.255.255
0 to 255
Host ID
1 to 254
0 to 255
Network ID
Class B:
Class C:
Range of addresses
Host ID
128 to 191
0 to 255
192 to 223
Network ID
0 to 255
192.0.0.0 to
223.255.255.255
Multicast address
Class D (multicast):
224 to 239
0 to 255
0 to 255
1 to 254
224.0.0.0 to
239.255.255.255
Class E (reserved):
240 to 255
0 to 255
0 to 255
1 to 254
240.0.0.0 to
255.255.255.255
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3
© Addison-Wesley Publishers 2000
Figure 3.17
IP packet layout
header
IP addres s of s ource
IP addres s of des tination
up to 64 kiloby tes
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3
© Addison-Wesley Publishers 2000
data
Figure 3.18
IPv6 header layout
Version (4 bits) Priority (4 bits )
Pay load length (16 bits )
Flow label (24 bits)
Next header (8 bits)
Hop limit (8 bits)
Sourc e address
(128 bits )
Destination addres s
(128 bits )
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3
© Addison-Wesley Publishers 2000
Figure 3.19
The MobileIP routing mechanism
Sender
Subsequent IP packets
tunnelled to FA
Mobile host MH
Address of FA
returned to sender
First IP packet
addressed to MH
Internet
Foreign agent FA
Home
agent
First IP packet
tunnelled to FA
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3
© Addison-Wesley Publishers 2000
Figure 3.20
Firewall configurations
a) Filtering router
Router/
filter
Protected intranet
Internet
w eb/ftp
s erv er
b) Filtering router and bastion
R/filter
Bastion
Internet
w eb/ftp
s erv er
c ) Sc reened s ubnet for bas tion
R/filter
Bastion
R/filter
Internet
w eb/ftp
s erv er
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3
© Addison-Wesley Publishers 2000
Figure 3.21
IEEE 802 network standards
IEEE No. Title
802.3
802.4
802.5
802.6
802.11
Reference
CSMA/CD Networks (Ethernet) [IEEE 1985a]
Token Bus Networks
[IEEE 1985b]
Token Ring Networks
[IEEE 1985c]
Metropolitan Area Networks
[IEEE 1994]
Wireless Local Area Networks [IEEE 1999]
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3
© Addison-Wesley Publishers 2000
Figure 3.22
Wireless LAN configuration
A
B
C
Laptops
radio obs truction
Palmtop
Server
D
E
Wireless
LAN
Base s tation/
acc es s point
LAN
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3
© Addison-Wesley Publishers 2000
Figure 3.23
ATM protocol layers
Mess age
Lay ers
Applic ation
Higher-lay er protoc ols
ATM adaption layer
ATM cells
ATM layer
ATM virtual channels
Phy sical
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3
© Addison-Wesley Publishers 2000
Figure 3.24
ATM cell layout
Header: 5 by tes
Virtual path id
Virtual channel id
Flags
Data
53 bytes
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3
© Addison-Wesley Publishers 2000
Figure 3.25
Switching virtual paths in an ATM network
Host
VPI = 2
VPI = 3
VPI = 4
VPI in VPI out
2
3
VP/VC
s w itch
VP sw itch
4
5
VPI = 5
VP sw itch
Host
VPI : virtual path identifier
Virtual path
Virtual channels
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3
© Addison-Wesley Publishers 2000