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Table Of Contents
Measuring Response Time in IP Networks
Measuring Response Time to an SNA Mainframe
Overview of IPM
This chapter provides an overview of Cisco's Internetwork Performance Monitor (IPM) application. It contains the following sections:
What Is IPM?
IPM is a network management application that allows you to monitor the performance of multi-protocol networks. IPM measures the response time and availability of IP networks on a hop-by-hop (router-to-router) basis. It also measures response time between routers and the mainframe in SNA (Systems Network Architecture) networks.
Use IPM to perform the following tasks:
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Troubleshoot problems by checking the network latency between devices
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The IPM product is composed of three parts, the IPM server, the IPM client application, and the RTR (response time reporter) feature of the Cisco IOS software. The focus of this document is the IPM network management application which includes the server and the client. In some cases, however, it is not possible to fully describe IPM without including information about the Cisco IOS RTR feature. Therefore, we have included some information about the Cisco IOS feature. Information about the RTR feature provided in the latest Cisco IOS software documentation take precedence over the information about the RTR feature contained in this document.
Key Terms and Concepts
An understanding of the following terms and concepts is helpful for using the IPM application:
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How Does IPM Work?
IPM measures response time between a source router and a target device. The target is either an IP-addressable device or an IBM MVS mainframe. If the target is an IP-addressable device, it is either a network device or a workstation. If the target is an IBM MVS mainframe, it must be running an IPM virtual telecommunications access method (VTAM) application called NSPECHO and on SNA response time is measured.
There are two types of measurements that you can take:
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The IPM application is used to configure the RTR agent in each source router and then extract and display the response-time information. The RTR agent in the router measures the actual response-time samples between itself and the target device. The IPM application extracts the response-time data every hour from each source router and stores the data in the IPM database. However, each collector can measure the response time between the source router and the target device more often. When you use the IPM configuration process, you specify the interval at which each measurement operation is performed by a collector. IPM also provides a real-time feature that allows you to immediately display the response-time data without waiting for the one-hour data collection interval. However, the data displayed in the Real Time window is not stored in the IPM database.
Measuring Response Time in IP Networks
In an IP network, you can request either an Echo or a PathEcho measurement.
If you request an Echo measurement, the Cisco IOS RTR feature in the source router issues an Internet Control Message Protocol (ICMP) ping to the target device and extracts the response-time data from the reply.
If you request a PathEcho measurement, the Cisco IOS RTR feature first issues a traceroute command to determine the path through the network from the specified source router to the specified target device. The data returned from the traceroute command contains the host name or IP address of each of the routers in the path. RTR then issues ICMP pings to each of the routers listed in the traceroute data. The ICMP ping returns statistics regarding the response time between the specified source and each of the routers.
Measuring Response Time to an SNA Mainframe
For SNA environments, IPM allows you to measure the response time to an MVS mainframe using the following types of SNA sessions:
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Because SNA is a connection-oriented protocol, the only type of measurement you can request is Echo.
When measuring response time to an SNA mainframe, IPM uses an SNA ping. The source router sends a block of data (a request) to an IPM-supplied mainframe echo program (NSPECHO). NSPECHO responds with a block of data (a response), which is used to determine the response time.
You can customize both the request and response sizes to model traffic flow for various applications.
Components of IPM
The IPM system is a modular design (). Some of the components are provided as part of the IPM application, others are provided as part of the Cisco IOS Software Release 11.2(8) or later or Cisco IOS Software Release 11.3(6) or later. The RTR feature contains the Cisco RTTMON MIB and the SNMP agent.
Figure 1-1 Components of IPM
The IPM application is comprised of two major components, the IPM server and the IPM client. Multiple IPM clients can connect to a single IPM server. If you are measuring response time in an SNA-over-TCP/IP environment, there is also a mainframe component required by the IPM application. These IPM application components are described in the following sections:
IPM Server Components
The components of IPM server are described in the following sections:
IPM Configuration Process
The IPM configuration process runs on a UNIX workstation and is used to configure and schedule IPM collectors on source routers. It is provided as part of the IPM server. The configuration process includes the following functions:
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IPM SNMP Server
The SNMP server resides on a UNIX workstation and is provided as part of the IPM server. The IPM configuration and IPM data retriever processes use SNMP to deploy collectors in the routers and to gather data from the RTTMON MIB.
IPM Data Retriever
The IPM data retriever resides on a UNIX workstation. It is provided as part of the IPM server. The data retriever performs the following tasks:
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IPM Relational Database
IPM includes an embedded relational database to manage its data. Several of the IPM processes interact with the relational database, including the following processes:
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IPM Display Server
The IPM display server runs on a UNIX workstation and is used by the IPM client to perform the following functions:
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The IPM display server is provided as part of the IPM server.
IPM Client Component
The IPM client runs on a UNIX or WindowsNT workstation. It provides a GUI to the IPM server to perform the following functions:
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RTR Feature Components
The RTR feature of the Cisco IOS software contains the components that are described in the following sections:
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SNMP Agent
The SNMP agent resides in the source router and is provided as part of Cisco IOS software. The SNMP agent receives requests from the IPM SNMP server to perform all IPM-related functions.
RTTMON MIB
The RTTMON MIB is a proprietary MIB created by Cisco to obtain and store round-trip time statistics. The MIB is implemented by the Cisco IOS software in the source router. The IPM application obtains the round-trip time statistics from this MIB. You can access additional information about this MIB, on the Internet at ftp://ftp.cisco.com/pub/mibs/v2/CISCO-RTTMON-MIB.my.
Collectors
An IPM collector is a user-defined entity on the source router that includes information about the target device, the protocol used for measuring response time, the frequency at which the response time is measured, and the amount of time for which response-time measurements are taken.
The purpose of an IPM collector is to capture statistics and error information from the IPM-enabled routers.
Mainframe Component
When measuring response time to an SNA mainframe, IPM measures round-trip response times between a source router and an echo program in an SNA mainframe. A program in the SNA mainframe is responsible for providing the echo back to the router. IPM provides a mainframe echo program (NSPECHO) that you can install on an MVS mainframe for this purpose.
