Chapter 8: Internet Operation Business Data Communications, 5e

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 Stallings, Business Data Communications, Fifth Edition, © 2005 Pearson Education, Inc. All rights reserved. 0-13-144257-0

Internet Addressing 32-bit global internet address Includes network and host identifiers Dotted decimal notation 11000000 11100100 00010001 00111001 (binary) 192.228.17.57 (decimal) Stallings, Business Data Communications, Fifth Edition, © 2005 Pearson Education, Inc. All rights reserved. 0-13-144257-0

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 Stallings, Business Data Communications, Fifth Edition, © 2005 Pearson Education, Inc. All rights reserved. 0-13-144257-0

Subnet Mask Calculations Stallings, Business Data Communications, Fifth Edition, © 2005 Pearson Education, Inc. All rights reserved. 0-13-144257-0

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 Stallings, Business Data Communications, Fifth Edition, © 2005 Pearson Education, Inc. All rights reserved. 0-13-144257-0

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 Stallings, Business Data Communications, Fifth Edition, © 2005 Pearson Education, Inc. All rights reserved. 0-13-144257-0

Border Grouping Protocol (BGP) Preferred ERP for the Internet Three functional procedures Neighbor acquisition Neighbor reachability Network reachability Stallings, Business Data Communications, Fifth Edition, © 2005 Pearson Education, Inc. All rights reserved. 0-13-144257-0

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 Stallings, Business Data Communications, Fifth Edition, © 2005 Pearson Education, Inc. All rights reserved. 0-13-144257-0

Autonomous System Example Stallings, Business Data Communications, Fifth Edition, © 2005 Pearson Education, Inc. All rights reserved. 0-13-144257-0

Directed Graph of Example Stallings, Business Data Communications, Fifth Edition, © 2005 Pearson Education, Inc. All rights reserved. 0-13-144257-0

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. 0-13-144257-0

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. 0-13-144257-0

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 Stallings, Business Data Communications, Fifth Edition, © 2005 Pearson Education, Inc. All rights reserved. 0-13-144257-0

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 Stallings, Business Data Communications, Fifth Edition, © 2005 Pearson Education, Inc. All rights reserved. 0-13-144257-0

Categories of Traffic Elastic Inelastic Can adjust to changes in delay and throughput access Examples: File transfer, e-mail, web access Inelastic Does not adapt well, if at all, to changes Examples: Real-time voice, audio and video Stallings, Business Data Communications, Fifth Edition, © 2005 Pearson Education, Inc. All rights reserved. 0-13-144257-0

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 Stallings, Business Data Communications, Fifth Edition, © 2005 Pearson Education, Inc. All rights reserved. 0-13-144257-0

Application Delay Sensitivity Stallings, Business Data Communications, Fifth Edition, © 2005 Pearson Education, Inc. All rights reserved. 0-13-144257-0

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. Stallings, Business Data Communications, Fifth Edition, © 2005 Pearson Education, Inc. All rights reserved. 0-13-144257-0

DS Service: Performance Parameters Constraints on ingress/egress points Traffic profiles Disposition of excess traffic Stallings, Business Data Communications, Fifth Edition, © 2005 Pearson Education, Inc. All rights reserved. 0-13-144257-0

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. Stallings, Business Data Communications, Fifth Edition, © 2005 Pearson Education, Inc. All rights reserved. 0-13-144257-0

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 Stallings, Business Data Communications, Fifth Edition, © 2005 Pearson Education, Inc. All rights reserved. 0-13-144257-0

DS Configuration Diagram Stallings, Business Data Communications, Fifth Edition, © 2005 Pearson Education, Inc. All rights reserved. 0-13-144257-0

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 Stallings, Business Data Communications, Fifth Edition, © 2005 Pearson Education, Inc. All rights reserved. 0-13-144257-0

Traffic Conditioning Diagram Stallings, Business Data Communications, Fifth Edition, © 2005 Pearson Education, Inc. All rights reserved. 0-13-144257-0

Token Bucket Scheme Stallings, Business Data Communications, Fifth Edition, © 2005 Pearson Education, Inc. All rights reserved. 0-13-144257-0