© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public 1 Version 4.0 Identifying Application Impacts on Network Design Designing and Supporting Computer Networks – Chapter 4

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public 2 Objectives  Explain how applications and traffic flow can affect the design of the network  Identify application impacts on network design  Explain how Quality of Service is implemented on the LAN/WAN  Explain the options for supporting voice and video traffic on the network  Document the network requirements of specific categories of applications and diagram the application traffic flows through the network

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public 3 Explain How Applications and Traffic Flow Can Affect the Network Design  Application performance depends on availability and responsiveness  Measurement: user satisfaction, throughput, technical metrics

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public 4 Explain How Applications and Traffic Flow Can Affect the Network Design Four main types of application communication:  Client-to-client  Client-to-distributed server  Client-to-server farm  Client-to-enterprise edge

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public 5 Characterize applications by gathering information:  Organizational output  Network audit  Traffic analysis Explain How Applications and Traffic Flow Can Affect the Network Design

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public 6 Characterize applications by gathering information:  Organizational output  Network audit  Traffic analysis Lets find top talkers Explain How Applications and Traffic Flow Can Affect the Network Design Router(config)# ip cef Router(config)# interface ser 0/1 Router(config-if)# ip route-cache flow Router# show ip cache flow And better yet, if your version of software supports it... Turn on netflow as above and... Router(config)# ip flow-top-talkers Router(config-flow-top-talkers)# top 10 The following is the top ten talkers in network sorted by packets: Router# show ip flow top-talkers You should expect increased CPU overhead to provide these statistics.....interface

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public 7 Explain How Applications and Traffic Flow Can Affect the Network Design  Internal traffic: identify areas where high bandwidth is needed, and possible bottlenecks  External traffic: determine placement of firewalls and DMZ networks

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public 8 Explain How Applications and Traffic Flow Can Affect the Network Design  Installed hardware affects application performance  Choose hardware after analyzing technical requirements

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public 9 Identifying Application Impacts on Network Design Transaction-processing applications:  Additional operations required  Immediate response to user requests  Redundancy and security required

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public 10 Identifying Application Impacts on Network Design Real-time streaming applications:  Minimize latency and jitter  Infrastructure may need to be upgraded

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public 11 Identifying Application Impacts on Network Design File transfer and applications:  Unpredictable bandwidth usage  Large packet size  Centralization of file and mail servers in a secure location  Redundancy to ensure reliable service

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public 12 Identifying Application Impacts on Network Design HTTP and web traffic:  Network media  Redundancy  Security

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public 13 Identifying Application Impacts on Network Design Microsoft Domain Services:  Active Directory Services  Broadcast generation  Tight integration between ADS, DNS, and DHCP

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public 14 Explain how Quality of Service is Implemented on the LAN/WAN  Capability of a network to provide preferential service to selected network traffic  Dedicated bandwidth, controlled jitter and latency, and reduced packet loss

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public 15 Explain how Quality of Service is Implemented on the LAN/WAN Implementing traffic queues:  Identify traffic requirements  Define traffic classes  Define QoS policies

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public 16 Explain how Quality of Service is Implemented on the LAN/WAN Set priorities to manage traffic:  Queue type  Traffic assignment  Size  Filter traffic into high, medium, normal and low priorities

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public 17 Explain how Quality of Service is Implemented on the LAN/WAN Where QoS can be implemented to affect traffic flow:  Layer 2 devices  Layer 3 devices

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public 18 Explain the Options for Supporting Voice and Video Traffic on the Network Network design implications of converged networking:  Strong performance  Security features  Mandatory use of QoS mechanisms

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public 19 Explain the Options for Supporting Voice and Video Traffic on the Network Network design implications of IP telephony:  Power and capacity planning  Identifying contending traffic flows  Selecting components for the IP telephony solution

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public 20 Explain the Options for Supporting Voice and Video Traffic on the Network Live video:  Streaming media files  User sees content before all packets have arrived  No need to store large media files before playing them  Uses multicast packets to many users at the same time Video on Demand:  Either stream or download before viewing  Users can store content and view later  Unicast packets to a specific user requesting the service

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public 21 Explain the Options for Supporting Voice and Video Traffic on the Network Supporting remote workers with voice and video:  Assess bandwidth requirements for WAN connection  Permanent link or on-demand

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public 22 Document the Network Requirements of Specific Categories of Applications  Estimate the volume of application traffic during the initial design phase.  Document projected applications and associated hardware in a network diagram.

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public 23 Document the Network Requirements of Specific Categories of Applications  Diagram the flow of traffic to and from hosts and servers within the LAN

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public 24 Document the Network Requirements of Specific Categories of Applications  Diagram the flow of traffic to and from remote sites, including VPN traffic

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public 25 Document the Network Requirements of Specific Categories of Applications  Diagram outgoing traffic flows destined for the Internet gateway and incoming traffic from the Internet to locally-provided services

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public 26 Document the Network Requirements of Specific Categories of Applications  Diagram extranet traffic flows to and from selected trusted partners, customers, and vendors

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public 27 Summary  End users evaluate network performance based on the availability and responsiveness of their applications.  The choice of hardware installed on a network can affect the performance of the applications.  When adding a new application, the designer must consider the impact on the performance of existing applications.  Voice and video applications present unique requirements, as they cannot tolerate delays.  Security and reliability are primary concerns in a network supporting high volumes of web traffic.  The primary goal of QoS is to provide priority, dedicated bandwidth, controlled jitter and latency, and reduced packet loss.

© 2006 Cisco Systems, Inc. All rights reserved.Cisco Public 28