APC 78-10169-02 In-Band Versus Out-of-Band Monitoring, Evaluating Reachability and Response Times

Chapter 2 Monitoring the System

Monitoring with Cisco IOS Software

Evaluating Reachability and Response Times

Polling remote parts of the network enables you to test reachability and measure response times. Response-time measurements consist of sending a ping (packet internet groper) packet and measuring the round-trip time (RTT) that it takes to send the packet and receive a response. The ping packet is sent and received as an ICMP echo packet.

Note For information about ping command usage, see Chapter 4, “System Troubleshooting Guidelines,” and Chapter 7, “Solving Serial Connection Problems.”

Caution Polling activity can result in a significant increase in network traffic. Therefore it is important to carefully assess what level of monitoring is appropriate for your organization.

Evaluating Traffic Loads

You can use protocol analyzers or SNMP tools to record traffic loads between important sources and destinations. (See Chapter 4, “System Troubleshooting Guidelines,” for additional information about protocol analyzers and other monitoring and troubleshooting tools.) The objective is to document how much data can pass between pairs of autonomous systems, networks, hosts, or applications. Source and destination traffic-load documentation is useful for capacity planning and troubleshooting. Source and destination traffic-load data is also useful if you have a service-level agreement that includes throughput requirements.

In-Band Versus Out-of-Band Monitoring

Another important factor affecting how and when you perform network monitoring is the degree to which monitoring either does or does not consume system bandwidth. Depending on how your network is structured, you can use in-band monitoring, out-of-band monitoring, or a combination of the two.

	Cisco ICS 7750 Administration and Troubleshooting Guide
78-10169-02 Rev. B0		2-19