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Characterizing the Existing Network and Sites

Applying a Methodology to Network Design

2007 Cisco Systems, Inc. All rights reserved.

DESGN v2.0—1-1

The PDF files and any printed representation for this material are the property of Cisco Systems, Inc., for the sole use by Cisco employees for personal study. The files or printed representations may not be

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 v2.0—1-2

The PDF files and any printed representation for this material are the property of Cisco Systems, Inc., for the sole use by Cisco employees for personal study. The files or printed representations may not be

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 v2.0—1-3

The PDF files and any printed representation for this material are the property of Cisco Systems, Inc., for the sole use by Cisco employees for personal study. The files or printed representations may not be

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 v2.0—1-4

The PDF files and any printed representation for this material are the property of Cisco Systems, Inc., for the sole use by Cisco employees for personal study. The files or printed representations may not be

Example: Customer Network Diagram

2007 Cisco Systems, Inc. All rights reserved.

DESGN v2.0—1-5

The PDF files and any printed representation for this material are the property of Cisco Systems, Inc., for the sole use by Cisco employees for personal study. The files or printed representations may not be

Network Assessment Information Sources

2007 Cisco Systems, Inc. All rights reserved.

DESGN v2.0—1-6

The PDF files and any printed representation for this material are the property of Cisco Systems, Inc., for the sole use by Cisco employees for personal study. The files or printed representations may not be

Example: Network Assessment

2007 Cisco Systems, Inc. All rights reserved.

DESGN v2.0—1-7

The PDF files and any printed representation for this material are the property of Cisco Systems, Inc., for the sole use by Cisco employees for personal study. The files or printed representations may not be

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 v2.0—1-8

The PDF files and any printed representation for this material are the property of Cisco Systems, Inc., for the sole use by Cisco employees for personal study. The files or printed representations may not be

Commands for Manual Information Collection

2007 Cisco Systems, Inc. All rights reserved.

DESGN v2.0—1-9

The PDF files and any printed representation for this material are the property of Cisco Systems, Inc., for the sole use by Cisco employees for personal study. The files or printed representations may not be

Example: Manual Information Collection—Router CPU Utilization

2007 Cisco Systems, Inc. All rights reserved.

DESGN v2.0—1-10

The PDF files and any printed representation for this material are the property of Cisco Systems, Inc., for the sole use by Cisco employees for personal study. The files or printed representations may not be

Example: Manual Information Collection—Router Memory Utilization

2007 Cisco Systems, Inc. All rights reserved.

DESGN v2.0—1-11

The PDF files and any printed representation for this material are the property of Cisco Systems, Inc., for the sole use by Cisco employees for personal study. The files or printed representations may not be

Example: Automatic Information Collection—Cacti Device List

2007 Cisco Systems, Inc. All rights reserved.

DESGN v2.0—1-12

The PDF files and any printed representation for this material are the property of Cisco Systems, Inc., for the sole use by Cisco employees for personal study. The files or printed representations may not be

Example: Automatic Information Collection—NetMRI Inventory

2007 Cisco Systems, Inc. All rights reserved.

DESGN v2.0—1-13

The PDF files and any printed representation for this material are the property of Cisco Systems, Inc., for the sole use by Cisco employees for personal study. The files or printed representations may not be

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 v2.0—1-14

The PDF files and any printed representation for this material are the property of Cisco Systems, Inc., for the sole use by Cisco employees for personal study. The files or printed representations may not be

Steps in Analyzing Network Traffic

2007 Cisco Systems, Inc. All rights reserved.

DESGN v2.0—1-15

The PDF files and any printed representation for this material are the property of Cisco Systems, Inc., for the sole use by Cisco employees for personal study. The files or printed representations may not be

Example: Traffic Analysis
Application No. 8:
Description: Protocol: Servers: Clients: Scope: Importance: Average rate: Mbps Accounting software TCP port 5151 2 50 Campus High 50 kbps with 10-second bursts to 1

2007 Cisco Systems, Inc. All rights reserved.

DESGN v2.0—1-16

The PDF files and any printed representation for this material are the property of Cisco Systems, Inc., for the sole use by Cisco employees for personal study. The files or printed representations may not be

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 v2.0—1-17

The PDF files and any printed representation for this material are the property of Cisco Systems, Inc., for the sole use by Cisco employees for personal study. The files or printed representations may not be

Example: NBAR Printout

2007 Cisco Systems, Inc. All rights reserved.

DESGN v2.0—1-18

The PDF files and any printed representation for this material are the property of Cisco Systems, Inc., for the sole use by Cisco employees for personal study. The files or printed representations may not be

Example: Cisco IOS NetFlow Printout

2007 Cisco Systems, Inc. All rights reserved.

DESGN v2.0—1-19

The PDF files and any printed representation for this material are the property of Cisco Systems, Inc., for the sole use by Cisco employees for personal study. The files or printed representations may not be

Example: Cacti Graph

2007 Cisco Systems, Inc. All rights reserved.

DESGN v2.0—1-20

The PDF files and any printed representation for this material are the property of Cisco Systems, Inc., for the sole use by Cisco employees for personal study. The files or printed representations may not be

Example: Solarwinds Orion

2007 Cisco Systems, Inc. All rights reserved.

DESGN v2.0—1-21

The PDF files and any printed representation for this material are the property of Cisco Systems, Inc., for the sole use by Cisco employees for personal study. The files or printed representations may not be

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 v2.0—1-22

The PDF files and any printed representation for this material are the property of Cisco Systems, Inc., for the sole use by Cisco employees for personal study. The files or printed representations may not be

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 v2.0—1-23

The PDF files and any printed representation for this material are the property of Cisco Systems, Inc., for the sole use by Cisco employees for personal study. The files or printed representations may not be

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 v2.0—1-24

The PDF files and any printed representation for this material are the property of Cisco Systems, Inc., for the sole use by Cisco employees for personal study. The files or printed representations may not be

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 v2.0—1-25

The PDF files and any printed representation for this material are the property of Cisco Systems, Inc., for the sole use by Cisco employees for personal study. The files or printed representations may not be

Documenting an Existing Network

2007 Cisco Systems, Inc. All rights reserved.

DESGN v2.0—1-26

The PDF files and any printed representation for this material are the property of Cisco Systems, Inc., for the sole use by Cisco employees for personal study. The files or printed representations may not be

Network Characterization Hour Estimates
Small Network
1–20 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 44–48 86–98 132–180 288–384 4 4 16 8 4 16 16 4 32 16 8 32 24 8 48 24 16 48 40 16 80 40 32 80 4 4 4 4 4 4 4 4 4 4

Medium Network
20–200 Switches/Routers 8 6 6 6 8 8 6 6 6 16

Large Network
200–800 Switches/Routers 12 8 8 8 16 12 12 12 8 48

Huge Network
>800 Switches/Routers 16 24 16 16 80 16 24 16 16 160

2007 Cisco Systems, Inc. All rights reserved.

DESGN v2.0—1-27

The PDF files and any printed representation for this material are the property of Cisco Systems, Inc., for the sole use by Cisco employees for personal study. The files or printed representations may not be

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 v2.0—1-28

The PDF files and any printed representation for this material are the property of Cisco Systems, Inc., for the sole use by Cisco employees for personal study. The files or printed representations may not be

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 v2.0—1-29

The PDF files and any printed representation for this material are the property of Cisco Systems, Inc., for the sole use by Cisco employees for personal study. The files or printed representations may not be

2007 Cisco Systems, Inc. All rights reserved.

DESGN v2.0—1-30

The PDF files and any printed representation for this material are the property of Cisco Systems, Inc., for the sole use by Cisco employees for personal study. The files or printed representations may not be


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