Specifications

© 2006 Cisco Systems, Inc.
All rights reserved.
Introduction 1-14
NAM / Traffic Analyzer v3.5 Tutorial
© 2006 Cisco Systems, Inc. All rights reserved.
Introduction 1-14
NAM / Traffic Analyzer v3.5 Tutorial
Network Performance Monitoring
The Key to Performance Monitoring
Network Performance Monitoring
The Key to Performance Monitoring
OSI
Protocol
Layers
Obtain “visibility” into the
network at the upper layer
protocols
Obtain “visibility” into the
network at the upper layer
protocols
Data Link
Data Link
(MAC)
(MAC)
Application
Application
Presentation
Session
Transport
Network
Network
Physical
Physical
RMON-2
Standard
RMON-1
Standard
Data Link
Data Link
7
6
5
4
3
2
1
Visibility: The Answer to Some of Our Monitoring Needs
What is needed to solve some of the challenges that you face when it comes to monitoring your network?
Visibility, the ability to see and analyze the traffic that consumes the resources on your network, will help you
solve many of the management problems just mentioned. Visibility means many things in the context of
today’s complex networks, so to understand what is required and why, let’s look at the issues in more detail.
Network traffic consists of discrete units called packets. Everything you want to know about the traffic on your
network exists in the protocol headers of a packet. By examining the headers that are created at different
protocol layers, you can identify who is talking with whom, what QoS priority has been assigned to a packet,
what application created the packet, and so on. Just from the information in the packet headers, you can
create very meaningful reports that help you understand how your network is being used. Collecting
information from the packet itself is the best way to gain visibility into your network.
But visibility is not just about what you gather, it is also about where you gather it from. For example, most
networks today employ some form of layer 2 switching and VLANs at critical points in the network such as
aggregation points and server farms where a significant percentage of network traffic converges. Collecting
data from a switch itself provides visibility into the packets that traverse your network, the switch fabric, the
switch ports that provide access to application servers, and trunk ports where traffic aggregates. Additionally,
monitoring traffic at the edge of the network provides visibility into the users and applications at crucial
access points or at costly WAN links.
Monitoring directly at the Catalyst switch or branch router provides other benefits as well. It also offers the
ability to monitor critical devices, such as servers, closest to their source at the port that connects the
devices to the network. This enables you to collect information from a response-time perspective because
traffic can be time stamped as it enters and exits ports. Collecting response-time data provides a direct way
to measure the end user’s experience of your network. That is visibility!