Download Figure 3.1 Network types

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
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3
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Figure 3.2
Conceptual layering of protocol software
Message received
Message sent
Layer n
•
•
Layer 2
Layer 1
Sender
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3
Communication
medium
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Recipient
2
Figure 3.3
Encapsulation as it is applied in layered protocols
Application-layer message
Presentation header
Session header
Transport header
Network header
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Figure 3.4
Protocol layers in the ISO Open Systems Interconnection (OSI) protocol model
Message received
Message sent
Layers
Application
Presentation
Session
Transport
Network
Data link
Physical
Sender
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3
Communication
medium
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Recipient
4
Figure 3.5
OSI protocol summary
Layer
Application
Description
Protocols that are designed to meet the communication requirements of
specific applications, often defining the interface to a service.
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.
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).
Session
Transport
Network
Data link
Physical
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3
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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 baseband
signalling,
ISDN
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Figure 3.6
Internetwork layers
Message
Layers
Application
Internetwork
protocols
Transport
Internetwork
Internetwork packets
Network interface
Network-specific packets
Underlying network
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Underlying
network
protocols
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Figure 3.7
Routing in a wide area network
1
A
Hosts
or local
networks
3
B
2
Links
4
C
5
D
6
E
Routers
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Figure 3.8
Routing tables for the network in Figure 3.7
Routings from A
To
A
B
C
D
E
Link
local
1
1
3
1
Routings from B
Cost
0
1
2
1
2
To
A
B
C
D
E
Link
1
local
2
1
4
Routings from D
To
A
B
C
D
E
Link
3
3
6
local
6
Cost
1
0
1
2
1
To
A
B
C
D
E
Link
2
2
local
5
5
Cost
2
1
0
2
1
Routings from E
Cost
1
2
2
0
1
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3
Routings from C
To
Link
Cost
A
B
C
D
E
4
4
5
6
local
2
1
1
1
0
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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
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Figure 3.10
Simplified view of the QMW Computer Science network
Campus 138.37.95.240/29
subnet
router
138.37.95.241
hammer
Student subnet
Staff subnet
138.37.88.251
138.37.88
compute
server
router/
firewall
138.37.94.251
Eswitch
138.37.94
Eswitch
bruno
138.37.88.249
☎
file server/
gateway
custard
138.37.94.246
dialup
server
henry
138.37.88.230
other
servers
file
server
138.37.95.232/29
subnet
hotpoint
138.37.88.162
web
server
hub
desktop computers 138.37.88.xx
138.37.95.248/29
subnet
138.37.94.247
hub
138.37.88.247
copper
138.37.88.248
Campus
router
printers
desktop computers 138.37.94.xx
sickle
138.37.95.249
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3
router/
firewall
100 Mbps Ethernet
1000 Mbps Ethernet
Eswitch: Ethernet switch
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Figure 3.11
Tunnelling for IPv6 migration
IPv6 encapsulated in IPv4 packets
IPv4 network
A
IPv6
IPv6
B
Encapsulators
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Figure 3.12
TCP/IP layers
Layers
Message
Application
Messages (UDP) or Streams (TCP)
Transport
UDP or TCP packets
Internet
IP datagrams
Network interface
Network-specific frames
Underlying network
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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
port
TCP
IP
Ethernet frame
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Figure 3.14
The programmer's conceptual view of a TCP/IP Internet
Application
Application
TCP
UDP
IP
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Figure 3.15
Internet address structure, showing field sizes in bits
Class A:
Class B:
0
7
24
Network ID
Host ID
1 0
14
16
Network ID
Host ID
21
Class C:
1 1 0
8
Network ID
Host ID
28
Class D (multicast):
1 1 1 0
Multicast address
27
Class E (reserved):
1 1 1 1 0
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3
unused
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Figure 3.16
Decimal representation of Internet addresses
octet 1
octet 2
Network ID
Class A:
Class B:
Class C:
1 to 127
Range of addresses
Host ID
0 to 255
Network ID
128 to 191
0 to 255
192 to 223
octet 3
Network 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
1 to 254
224.0.0.0 to
239.255.255.255
1 to 254
240.0.0.0 to
255.255.255.255
0 to 255
Host ID
Class D (multicast):
224 to 239
Multicast address
0 to 255
0 to 255
Class E (reserved):
240 to 255
0 to 255
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3
0 to 255
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192.0.0.0 to
223.255.255.255
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Figure 3.17
IP packet layout
header
IP address of source
IP address of destination
up to 64 kilobytes
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3
© Pearson Education 2001
data
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Figure 3.18
IPv6 header layout
Version (4 bits) Priority (4 bits)
Flow label (24 bits)
Next header (8 bits)
Payload length (16 bits)
Hop limit (8 bits)
Source address
(128 bits)
Destination address
(128 bits)
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3
© Pearson Education 2001
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Figure 3.19
The MobileIP routing mechanism
Sender
Address of FA
returned to sender
Subsequent IP packets
tunnelled to FA
Mobile host MH
First IP packet
addressed to MH
Internet
Home
agent
Foreign agent FA
First IP packet
tunnelled to FA
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© Pearson Education 2001
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Figure 3.20
Firewall configurations
a) Filtering router
Router/
filter
Protected intranet
Internet
web/ftp
server
b) Filtering router and bastion
R/filter Bastion
Internet
web/ftp
server
c) Screened subnet for bastion
R/filter Bastion R/filter
Internet
web/ftp
server
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© Pearson Education 2001
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Figure 3.21
IEEE 802 network standards
IEEE No.
802.3
802.4
802.5
802.6
802.11
Title
CSMA/CD Networks (Ethernet)
Token Bus Networks
Token Ring Networks
Metropolitan Area Networks
Wireless Local Area Networks
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3
© Pearson Education 2001
Reference
[IEEE 1985a]
[IEEE 1985b]
[IEEE 1985c]
[IEEE 1994]
[IEEE 1999]
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Figure 3.22
Wireless LAN configuration
A
B
C
Laptops
radio obstruction
Palmtop D
E
Wireless
LAN
Base station/
access point
Server
LAN
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Figure 3.23
ATM protocol layers
Message
Layers
Application
Higher-layer protocols
ATM adaption layer
ATM cells
ATM layer
ATM virtual channels
Physical
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3
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Figure 3.24
ATM cell layout
Header: 5 bytes
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
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Figure 3.25
Switching virtual paths in an ATM network
Host
VPI = 2
VPI = 3
VP/VC
switch
VP switch
VPI = 4
VPI in VPI out
2
3
4
5
VPI = 5
VP switch
Host
VPI : virtual path identifier
Virtual path
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Virtual channels
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