Download Overview of Computer Networks

CPET 355
16.
Internetworking, Addressing, and
Routing
Paul I-Hai Lin, Professor
Electrical and Computer Engineering Technology
Purdue University, Fort Wayne Campus
November 29, 2004
Prof. Paul Lin
1
Network Layer - an Overview
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Getting data packets from the source
all the way to the destination
Dealing with end-to-end transmission
Need to know
• Topology of the communication subnet
(routers)
• Chose paths (routing algorithms)
November 29, 2004
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Position of Network Layer
Courtesy - From Fig. 1, Page 467, Data Communications and
Networks, 3rd edition, Forouzan, McGrawHill
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3
Network Layer Duties
Courtesy - From Fig. 2, Page 468, Data Communications and
Networks, 3rd edition, Forouzan, McGrawHill
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Network Layer
Topics of Discussion
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Network Layer Design Issue
• Services to the TCP Layer
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Connectionless Services (Datagram)
Connection-Oriented Services (Virtual
Circuit)
• Subnets
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Internetworking
Addressing
Routing
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Internetworks
Host A -> Host D
• 4 LANS, 1 WAN
• S1, S2, S3: Switch or Router
• f1, f2: Interface
• Three links: S1 -> S2 -> s3
Courtesy - From Fig. 19.1, Page 471, Data Communications and Networks, 3rd edition, Forouzan, McGrawHill
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Links in an Internetwork
Courtesy - From Fig. 19.2, Page 472, Data Communications and Networks, 3rd edition, Forouzan, McGrawHill
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Network Layer in an Internetwork
Courtesy - From Fig. 19.3 Page 473, Data Communications and Networks, 3rd edition, Forouzan, McGrawHill
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Network Layer at the Source
• Creating Source and Destination Address, Fragmentation
Courtesy - From Fig. 19.4 Page 473, Data Communications and Networks, 3rd edition, Forouzan, McGrawHill
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Network Layer at Router or Switch
• Routing Table, Fragmentation
Courtesy - From Fig. 19.5 Page 474, Data Communications and Networks, 3rd edition, Forouzan, McGrawHill
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Network Layer at Destination
• Corrupted packet, Fragments
Courtesy - From Fig. 196 Page 475, Data Communications and Networks, 3rd edition, Forouzan, McGrawHill
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Quality of Service
Requirements
From Fig. 5-30, Page 397, Computer Networks, 4th edition,
Andrew S. Tanenbaum, Prentice Hall
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Packet-Switched Network - Internet
• Packets – Variable Length Data Blocks; Node to Node
Delivery
• Virtual Circuit – WAN, Frame Relaying, ATM applications, call
setup a single route
Courtesy - From Fig. 196 Page 475, Data Communications and Networks, 3rd edition, Forouzan, McGrawHill
November 29, 2004
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Packet-Switched Network - Internet
• Datagram Approach – no fixed path, routing, out of order
• Packets == Datagrams
Courtesy - From Fig. 196 Page 475, Data Communications and Networks, 3rd edition, Forouzan, McGrawHill
November 29, 2004
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Addressing
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Internet Address – IP Address
• Classful addressing – original architecture
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Class A, B, C, D, and E
• Classless addressing – mid 1990s
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IPv4
• 32-bit binary number
• Dotted-Decimal Notation
128.11.3.31
255.255.255.0
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IPv6 - 128-bit
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Addressing – IPV4
• Network ID, Host ID
• Class A – 128 blocks (First Byte), 16,777,216 hosts
• Class B – 16,384 blocks (First & Second Byte), 65536 hosts
• Class C – 2,097,152 blocks (First, Second, Third byte), 256 hosts
• Class D – 1 block, Multicasting
Courtesy - From Fig. 19.10 Page 479, Data Communications and Networks, 3rd edition, Forouzan, McGrawHill
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Finding the Class
Courtesy - From Fig. 19.12 Page 480, Data Communications and Networks, 3rd edition, Forouzan, McGrawHill
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Netid and Hostid
Courtesy - From Fig. 19.13 Page 481, Data Communications and Networks, 3rd edition,
Forouzan, McGrawHill
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Classes and Blocks - Netid 73
128 Blocks; 16,777,216 Hosts
Courtesy - From Fig. 19.14 Page 482, Data Communications and Networks, 3rd edition, Forouzan, McGrawHill
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Blocks in Class B Network
16384 Blocks; 65536 Hosts
Courtesy - From Fig. 19.15 Page 483, Data Communications and Networks, 3rd edition, Forouzan, McGrawHill
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Blocks in Class C Network
2,097,152 Blocks; 255 Hosts
Courtesy - From Fig. 19.16 Page 484, Data Communications and Networks, 3rd edition, Forouzan, McGrawHill
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Network Address
• An address defines a network with all host-id = 0
Courtesy - From Fig. 19.17 Page 484, Data Communications and Networks, 3rd edition, Forouzan, McGrawHill
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Sample Internet
Courtesy - From Fig. 19.18 Page 486, Data Communications and Networks, 3rd edition, Forouzan, McGrawHill
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Subnetting
• Class B – 1 block, 65536 hosts (16-bit)
• Subnets
• 2 sub-blocks (1-bit), 36768 hosts (15-bit)
• 4 sub-blocks (2-bit), 18384 hosts (14-bit)
•…
• 128 sub-blocks (7-bit), 512 host (9-bit)
Courtesy - From Fig. 19.19 Page 487, Data Communications and Networks, 3rd edition, Forouzan, McGrawHill
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Subnetting – 3 Level Hierarchy
• Three levels: Site, Subnet, Host
Courtesy - From Fig. 19.20 Page 487, Data Communications and Networks, 3rd edition, Forouzan, McGrawHill
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A Network With and Without Subnetting
Courtesy - From Fig. 19.21 Page 488, Data Communications and Networks, 3rd edition, Forouzan, McGrawHill
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Masks
Class
In Binary
In DottedDecimal
Using Slash
A
11111111 00000000 00000000 00000000
255.0.0.0
/8
B
11111111 11111111 00000000 00000000
255.255.0.0
/16
C
11111111 111111111 11111111 00000000
255.255.255.0
/24
Courtesy - From Table 19.1 Page 489, Data Communications and Networks, 3rd edition, Forouzan, McGrawHill
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Supernetting
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An organization can combine several
class C block to form a larger range of
addresses
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Classless Addressing
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Variable-Length Block (2, 4, 128, etc)
Mask
Finding the Network Address
Subnetting
CIDR (Classes InterDomain Routing)
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Dynamic Address Configuration

DHCP (Dynamic Host Configuration
Protocol)
• Database 1 (static) - Physical addresses to
IP addresses
• Database 2 (dynamic) – Available IP, Lease
Time
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Network Address Translation
• Internally, a large set of addresses
• Externally, one address, or a small set of addresses
Range
Total
10.0.0.0
to
10.255.255.255
224
172.16.0.0
to
172.31.255.255
220
192.168.255.255
216
192.168.0.0 to
Courtesy – Table 19.2 Page 494, Data Communications and Networks, 3rd edition, Forouzan, McGrawHill
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A NAT Example
• Private address: 172.18.0.0 to 172.18.255.255
• NAT Router address: 200.24.5.8
Courtesy – Fig 19.25 Page 495, Data Communications and Networks, 3rd edition, Forouzan, McGrawHill
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Address Translation
• Private address: 172.18.0.0 to 172.18.255.255
• NAT Router address: 200.24.5.8
Courtesy – Fig. 19.25 Page 495, Data Communications and Networks, 3rd edition, Forouzan, McGrawHill
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Address Translation (cont.)
Courtesy – Fig. 19.25 Page 495, Data Communications and Networks, 3rd edition, Forouzan, McGrawHill
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Translation Table
Private
Address
Private
Port
External
Address
External
Port
Transport
Protocol
172.18.3.1
1400
25.8.3.2
80
TCP
172.18.3.2
1401
25.8.3.2
80
TCP
...
...
...
...
...
Courtesy – Table 19.3 Page 497, Data Communications and Networks, 3rd edition, Forouzan, McGrawHill
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Routing Techniques
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Routing Tables
Next-Hop Routing
Network-Specific Routing
Host-Specific Routing
Default Routing
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Translation Table
Courtesy – Fig. 19.27 Page 496, Data Communications and Networks, 3rd edition, Forouzan, McGrawHill
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Next-Hop Routing
Courtesy – Fig. 19.28 Page 498, Data Communications and Networks, 3rd edition, Forouzan, McGrawHill
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Network-Specific Routing
Courtesy – Fig. 19.29 Page 498, Data Communications and Networks, 3rd edition, Forouzan, McGrawHill
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Host-Specific Routing
Courtesy – Fig. 19.30 Page 499, Data Communications and Networks, 3rd edition, Forouzan, McGrawHill
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Default Routing
Courtesy – Fig. 19.31 Page 500, Data Communications and Networks, 3rd edition, Forouzan, McGrawHill
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More on Routing
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Static vs Dynamic
• Static Routing Table
• Dynamic Routing Table and Protocols
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RIP – Routing Information Protocol
OSPF – Open Shortest Path First
BGF – Border Gateway Protocol
Routing Tables
• For Classful Addressing
• For Classless Addressing (CIDR)
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