1. Chapter 8: Internet Operation
Business Data Communications, 5e

2. Network Classes
Class A: Few networks, each with many hosts All addresses begin with binary 0
Class B: Medium networks, medium hosts All addresses begin with binary 10
Class C: Many networks, each with few hosts All addresses begin with binary 11
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3. Internet Addressing 32-bit global internet address
Includes network and host identifiers
Dotted decimal notation
(binary)
(decimal)
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4. Subnets & Subnet Masks
Allows for subdivision of internets within an organization
Each LAN can have a subnet number, allowing routing among networks
Host portion is partitioned into subnet and host numbers
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5. Subnet Mask Calculations
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6. Internet Routing Protocols
Responsible for receiving and forwarding packets between interconnected networks
Must dynamically adapt to changing network conditions
Two key concepts
Routing information
Routing algorithm
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7. Autonomous Systems Key characteristics
Set of routers and networks managed by single organization
group of routers exchanging information via a common routing protocol
connected (in a graph-theoretic sense); that is, there is a path between any pair of nodes
Interior Router Protocol (IRP) passes information between routers in an AP
Exterior Router Protocol (ERP) passes information between routers in different Aps
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8. Border Grouping Protocol (BGP)
Preferred ERP for the Internet
Three functional procedures
Neighbor acquisition
Neighbor reachability
Network reachability
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9. Open Shortest Path First (OSPF)
Widely used as IRP in TCP/IP networks
Uses link state routing algorithm
Routers maintain topology database of AS
Vertices
Router
Network
Transit
Stub
Edges
Connecting router vertices
Connecting router vertex to network vertex
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10. Autonomous System Example
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11. Directed Graph of Example
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12. The “Need for Speed” and Quality of Service (QoS)
Image-based services on the Internet (i.e., the Web) have led to increases in users and traffic volume
Resulting need for increased speed
Lack of increased speed reduced demand
QoS provides for varying application needs in Internet transmission
Stallings, Business Data Communications, Fifth Edition, © 2005 Pearson Education, Inc. All rights reserved

13. Emergence of High-Speed LANs
Until recently, internal LANs were used primarily for basic office services
Two trends in the 1990s changed this
Increased power of personal computers
MIS recognition of LAN value for client/server and intranet computing
Effect has been to increase volume of traffic over LANs
Result exceeds capacity of standard 10mbps and 16mbps networks
Stallings, Business Data Communications, Fifth Edition, © 2005 Pearson Education, Inc. All rights reserved

14. Corporate WAN Neds Greater dispersal of employee base
Changing application structures
Increased client/server and intranet
Wide deployment of GUIs
Dependence on Internet access
More data must be transported off premises and into the wide area
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15. Digital Electronics
Major contributors to increased image and video traffic
DVD (Digital Versatile Disk)
Increased storage means more information to transmit
Digital cameras
Camcorders
Still Image Cameras
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16. Categories of Traffic Elastic Inelastic
Can adjust to changes in delay and throughput access
Examples: File transfer, , web access
Inelastic
Does not adapt well, if at all, to changes
Examples: Real-time voice, audio and video
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17. Requirements of Inelastic Traffic
Throughput
Minimum value may be required
Delay
Services like market quotes are delay-sensitive
Delay variation
Real-time applications, like teleconferencing, have upper bounds on delay variation
Packet loss
Applictions vary in the amount of packet loss allowable
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18. Application Delay Sensitivity
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19. Differentiated Services
Provide QoS on the basis of user needs rather than data flows
IP packets labeled for differing QoS treatment
Service level agreement (SLA) established between the provider (internet domain) and the customer prior to the use of DS.
Provides a built-in aggregation mechanism.
Implemented in routers by queuing and forwarding packets based on the DS octet.
Routers do not have to save state information on packet flows.
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20. DS Service: Performance Parameters
Constraints on ingress/egress points
Traffic profiles
Disposition of excess traffic
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21. DS Services Provided
Traffic offered at service level A will be delivered with low latency.
Traffic offered at service level B will be delivered with low loss.
90% of in-profile traffic delivered at service level C will experience no more than 50 ms latency.
95% of in-profile traffic delivered at service level D will be delivered.
Traffic offered at service level E will be allotted twice the bandwidth of traffic delivered at service level F
Traffic with drop precedence X has a higher probability of delivery than traffic with drop precedence Y.
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22. DS Field
Packets labeled for handling in 6-bit DS field in the IPv4 header, or the IPv6 header
Value of field is “codepoint”
6-bits allows 64 codepoints in 3 pools
Form xxxxx0 - reserved for assignment as standards.
Form xxxx11 - reserved for experimental or local use.
Form xxxx01 - also reserved for experimental or local use, but may be allocated for future standards action as needed.
Precedence subfield indicates urgency
Route selection, Network service, Queuing discipline
RFC 1812 provides two categories of recommendations for queuing discipline
Queue Service
Congestion Control
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23. DS Configuration Diagram
Stallings, Business Data Communications, Fifth Edition, © 2005 Pearson Education, Inc. All rights reserved

24. DS Configuration & Operation
Routers are boundary or interior nodes
Forwarding treatment is per-hop behavior (PHB)
Boundary nodes handle traffic conditioning
Classifier
Meter
Marker
Shaper
Dropper
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25. Traffic Conditioning Diagram
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26. Token Bucket Scheme
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