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This chapter explains how to monitor the Cisco ICS 7750 and is organized as follows:
The Simple Network Management Protocol (SNMP) facilitates the exchange of management information between network devices. It is part of the Transmission Control Protocol/Internet Protocol (TCP/IP) protocol suite. SNMP enables you to manage network performance, find and solve network problems, and plan for network growth.
An SNMP managed network consists of three key components: managed devices, agents, and network management systems (NMSs).
Figure 2-1 shows the relationship between managed devices, agents, and NMSs.
The following system components, though not SNMP-managed devices, receive SNMP support through System Manager:
A Management Information Base (MIB) is a collection of information that is organized hierarchically. MIBs are accessed using a network management protocol such as SNMP. They comprise managed objects, which are identified by object identifiers.
A managed object (sometimes called a MIB object or an object) is one of any number of specific characteristics of a managed device. Managed objects are comprised of one or more object instances, which are essentially variables.
System MIB variables are accessible through SNMP as follows:
Instead of defining a large set of commands, SNMP places all operations in a get-request, get-next-request, and set-request format. For example, an SNMP manager can get a value from an SNMP agent or store a value in that SNMP agent.
On the Cisco ICS 7750, the System Manager software (the NMS) typically sends SNMP requests to a single IP address to access the SNMP MIBs of any system component. The SNMP agent can then respond to MIB-related queries being sent by the NMS. Similarly, if CiscoWorks2000 is the NMS, it uses the MIB variables to set device variables and poll devices on the network. You can then display the data that CiscoWorks2000 collects as a graph and analyze it to enhance network performance, monitor traffic loads, or troubleshoot problems. (See "Monitoring with CiscoWorks2000" later in this chapter.)
As shown in Figure 2-2, the SNMP agent gathers data from the MIB, which is the repository for information about device parameters and network data. The agent can send traps (see "Understanding Traps" later in this chapter) to the manager.
The SNMP manager uses information in the MIB to perform the operations described in Table 2-1.
| Operation | Description |
|---|---|
get-request | Retrieves a value from a specific variable. |
get-next-request | Retrieves a value from a variable within a table. |
get-response | The reply to a get-request, get-next-request, and set-request sent by an NMS. |
set-request | Stores a value in a specific variable. |
trap | An unsolicited message sent by an SNMP manager indicating that some event has occurred. |
The Cisco ICS 7750 supports the following MIBs:
When an agent detects an alarm condition, it reacts by logging information about the time, type, and severity of the condition and generates a trap—or notification message—that is sent to certain IP addresses.
SNMP community strings authenticate access to MIB objects and function as embedded passwords.
The Cisco ICS 7750 uses a base community string, to which the string @SLOTnumber can be appended to form a composite community string:
base_community_string@SLOTnumber
where
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Note All SNMP requests with a composite community string of @SLOT9 or higher are directed to the SSP, which determines the proper SNMP message destination. |
For example, assuming that a particular SNMP request needs to reach an MRP card in slot 5, the following composite community string could be used:
ICS7750@SLOT5
where ICS7750 represents the standard system get or set community string.
You can modify the default read (get) and read/write (get-set) community strings with Cisco ICS 7700 System Manager. (Refer to the Cisco ICS 7700 System Manager User Guide.)
System Manager monitors the Cisco ICS 7750 as follows:
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Note For information about monitoring individual phones or the lines connecting those phones to the Cisco ICS 7750, refer to Cisco CallManager documentation. For additional information on monitoring the system with System Manager, refer to the Cisco ICS 7700 System Manager User Guide. |
CiscoWorks2000 uses SNMP to monitor and control system devices. You can integrate CiscoWorks2000 applications with other NMSs, such as HP OpenView.
CiscoWorks2000 applications extend industry-standard network management systems to facilitate checking the status of Cisco devices, maintaining device configurations and inventories, and troubleshooting device problems. CiscoWorks2000 applications for monitoring the SNMP devices on your network include:
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Note For examples of how to use CiscoWorks2000 to troubleshoot network problems, see "System Troubleshooting Guidelines." |
This section describes proven strategies to help you monitor your network.
Collecting, analyzing, and archiving system performance data is important in understanding how well your system is meeting your organization's needs. Important things to monitor are the behavior of network applications and protocols and the response time of individual devices such as multiservice route processor (MRP) cards and Catalyst 3524-PWR XL switches.
Common ways to monitor system performance include the following:
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 Internet Control Message Protocol (ICMP) echo packet.
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Note For information about ping command usage, see "System Troubleshooting Guidelines," and "Solving Serial Connection Problems." |
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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. |
You can use protocol analyzers or SNMP tools to record traffic loads between important sources and destinations. (See "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.
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.
With in-band monitoring, network management data is sent over the same paths as user traffic. This means that any problems on the network will be more difficult to solve because collecting troubleshooting data will take longer. Using management tools is beneficial even when the internetwork is congested, failing, or under a security attack.
With out-of-band monitoring, network management data travels on different paths than user data. NMSs and agents are linked by circuits that are separate from the internetwork. The circuits can use dial-up, ISDN, or other technologies. The separate circuits can be used all the time or they can be used as backup only when the primary internetwork path is broken.
You can use show EXEC commands to perform a variety of tasks:
Following are some commonly used show commands:
There are hundreds of other show commands available. For details on using and interpreting the output of show commands, refer to the "Router and Network Monitoring" chapter in the Cisco IOS Configuration Fundamentals Command Reference publication.
In IOS software Release 12.0(1)T or later, you can search and filter the output for show commands. This functionality is useful when you need to sort through large amounts of output, or if you want to exclude output that you do not need to see.
To use this functionality, enter a show command followed by the "pipe" character (|), one of the keywords begin, include, or exclude, and an expression that you want to search or filter on:
command | {begin | include | exclude} regular-expressionThe following is an example of a show interface command that provides information only about lines where the word "protocol" appears:
Cisco ICS 7750# show interface | include protocol FastEthernet0/0 is up, line protocol is up Serial4/0 is up, line protocol is up Serial4/1 is up, line protocol is up Serial4/2 is administratively down, line protocol is down Serial4/3 is administratively down, line protocol is down
For more information on search and filter functionality, refer to the "Using the Command-Line Interface" chapter in the Cisco IOS Configuration Fundamentals Configuration Guide.
Posted: Mon Oct 2 13:50:41 PDT 2000
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