© 2007 Cisco Systems, Inc. All rights reserved.DESGN v Applying a Methodology to Network Design Characterizing the Existing Network and Sites

© 2007 Cisco Systems, Inc. All rights reserved.DESGN v Characterizing the Existing Network and Sites Gather documentation and query the organization. Perform a site and network assessment to help detail the network. Consider performing traffic analysis on the existing network and applications.

© 2007 Cisco Systems, Inc. All rights reserved.DESGN v Identifying Major Features of the Network Collect the information about the planned and existing network infrastructure: –Site contact information –Network topology such as network devices, physical and logical links, external connections, encapsulations, bandwidths, IP addressing, routing protocols –Network services such as security, QoS, high availability, IP telephony, storage, and wireless –Network applications such as unified communications and video delivery Collect the information about expected network functionality. Identify network modules based on the given information.

© 2007 Cisco Systems, Inc. All rights reserved.DESGN v Sample Site Contact Questions What is the site location or name? What is the site address? What is the shipping address? Who is the site contact? Is this site owned and maintained by the customer? Is this a staffed site? What are the hours of operation? What are the building or room access procedures? Are there any special security or safety procedures? Are there any union or labor requirements or procedures? What are the locations of the equipment cabinets and racks?

© 2007 Cisco Systems, Inc. All rights reserved.DESGN v Example: Customer Network Diagram

© 2007 Cisco Systems, Inc. All rights reserved.DESGN v Network Assessment Information Sources

© 2007 Cisco Systems, Inc. All rights reserved.DESGN v Example: Network Assessment

© 2007 Cisco Systems, Inc. All rights reserved.DESGN v Network Assessment Tools Manual assessment: –Use monitoring commands on network devices on small networks. –Use scripting tools to collect information on large networks. Use existing management and auditing tools: –CiscoWorks –Third-party tools such as WhatsUp Gold, Castle Rock SNMPc, open source Cacti, Netcordia NetMRI, and NetQoS NetVoyant Use other tools to collect relevant information for the network devices: –Third-party tools such as Network General Sniffer, AirMagnet software and devices, and WildPackets AiroPeek

© 2007 Cisco Systems, Inc. All rights reserved.DESGN v Commands for Manual Information Collection

© 2007 Cisco Systems, Inc. All rights reserved.DESGN v Example: Manual Information CollectionRouter CPU Utilization

© 2007 Cisco Systems, Inc. All rights reserved.DESGN v Example: Manual Information CollectionRouter Memory Utilization

© 2007 Cisco Systems, Inc. All rights reserved.DESGN v Example: Automatic Information CollectionCacti Device List

© 2007 Cisco Systems, Inc. All rights reserved.DESGN v Example: Automatic Information CollectionNetMRI Inventory

© 2007 Cisco Systems, Inc. All rights reserved.DESGN v Network Traffic Analysis Use organizational input to identify the applications used in the existing network and their relative importance. Perform a traffic analysis to reveal additional applications used in the network. Use the results and organizational input to define QoS and security-related requirements for discovered applications.

© 2007 Cisco Systems, Inc. All rights reserved.DESGN v Steps in Analyzing Network Traffic

© 2007 Cisco Systems, Inc. All rights reserved.DESGN v Example: Traffic Analysis Application No. 8: Description:Accounting software Protocol: TCP port 5151 Servers: 2 Clients:50 Scope:Campus Importance:High Average rate:50 kbps with 10-second bursts to 1 Mbps

© 2007 Cisco Systems, Inc. All rights reserved.DESGN v Network Analysis Tools Cisco IOS Software analysis capabilities: –NBAR –NetFlow Cisco software-based network analyzers: –Cisco CNS NetFlow Collection Engine Third-party tools, such as: –Open source Cacti –Network General Sniffer –WildPackets EtherPeek and AiroPeek –SolarWinds Orion –Wireshark –RMON probes

© 2007 Cisco Systems, Inc. All rights reserved.DESGN v Example: NBAR Printout

© 2007 Cisco Systems, Inc. All rights reserved.DESGN v Example: Cisco IOS NetFlow Printout

© 2007 Cisco Systems, Inc. All rights reserved.DESGN v Example: Cacti Graph

© 2007 Cisco Systems, Inc. All rights reserved.DESGN v Example: Solarwinds Orion

© 2007 Cisco Systems, Inc. All rights reserved.DESGN v Summary Report Characterization of the existing network results in a summary report that is used to: Describe the software features required in the network Describe possible problems in the existing network Identify the actions needed to prepare the network for the implementation of the required features Influence the customer requirements

© 2007 Cisco Systems, Inc. All rights reserved.DESGN v Example: Equipment Summary Report The network uses 895 routers: 655 routers use Cisco IOS Software Release 12.2(10). 240 routers use an older Cisco IOS Software version.

© 2007 Cisco Systems, Inc. All rights reserved.DESGN v Example: Summary Report Problem Statement Requirement: Queuing in the WAN Identified problem: –Existing Cisco IOS Software version does not support new queuing technologies. –15 out of 19 routers with older Cisco IOS Software are in the WAN. –12 out of 15 routers do not have enough memory to upgrade to Cisco IOS Software Release 12.3 or later. –5 out of 15 routers do not have enough flash memory to upgrade to Cisco IOS Software Release 12.3 or later.

© 2007 Cisco Systems, Inc. All rights reserved.DESGN v Example: Summary Report Recommendations Recommended action: –12 memory upgrades to 64 MB –5 flash memory upgrades to 16 MB Options: –Replace hardware and software to support queuing. –Find an alternative mechanism for that part of the network. –Find an alternative mechanism and use it instead of queuing. –Evaluate the consequences of not implementing the required feature in that part of the network.

© 2007 Cisco Systems, Inc. All rights reserved.DESGN v Documenting an Existing Network

© 2007 Cisco Systems, Inc. All rights reserved.DESGN v Network Characterization Hour Estimates Small Network 1–20 Switches/Routers Medium Network 20–200 Switches/Routers Large Network 200–800 Switches/Routers Huge Network >800 Switches/Routers a) Interview management team b) Interview network team c) Review documentation d) Set up network discovery tool e) Resolve SNMP access and similar problems f) Allow tools to gather data g) Analyze captured data h) Prepare high level Layer 3 diagrams i) Prepare report stating conclusions j) Incrementally prepare network diagrams Estimated manpower in hours 44–4886–98132–180288–384

© 2007 Cisco Systems, Inc. All rights reserved.DESGN v Summary Characterizing an existing network entails gathering as much information about the network as possible. Organization input, a network audit, and traffic analysis provide the key information that you need. Identifying major features of the network involves gathering network documentation and querying the organization. The auditing process adds detail to the initial network documentation that you created from existing documentation and customer input. You can manually audit a small network, but you typically need automated tools to audit a large network. Traffic analysis verifies the set of applications and protocols used in the network and determines the traffic patterns of the applications.

© 2007 Cisco Systems, Inc. All rights reserved.DESGN v Summary (Cont.) Tools used for traffic analysis range from manual identification of applications using Cisco IOS Software commands in combination with NBAR or NetFlow to those where dedicated software- or hardware-based analyzers capture live packets or SNMP data. The result of the network characterization is a summary report describing the health of the network.

© 2007 Cisco Systems, Inc. All rights reserved.DESGN v