Serviceability Configuration and Maintenance Guide for Cisco Unified Presence Release 8.0, 8.5, and 8.6
Understanding Simple Network Management Protocol
Downloads: This chapterpdf (PDF - 245.0KB) The complete bookPDF (PDF - 2.33MB) | Feedback

Understanding Simple Network Management Protocol

Table Of Contents

Understanding Simple Network Management Protocol

About Simple Network Management Protocol Support

SNMP Basics

SNMP version 1 Support

SNMP version 2c Support

SNMP version 3 Support

SNMP Services

SNMP Community Strings and Users

SNMP Traps and Informs

SNMP Management Information Base (MIB)

SNMP Configuration Checklist

Troubleshooting SNMP


Understanding Simple Network Management Protocol


About Simple Network Management Protocol Support

SNMP Configuration Checklist

Troubleshooting SNMP

About Simple Network Management Protocol Support

SNMP Basics

SNMP version 1 Support

SNMP version 2c Support

SNMP version 3 Support

SNMP Services

SNMP Community Strings and Users

SNMP Management Information Base (MIB)

SNMP Traps and Informs

SNMP Basics

Simple Network Management Protocol (SNMP), an application layer protocol, facilitates the exchange of management information among network devices, such as nodes, routers, and so on. As part of the TCP/IP protocol suite, SNMP enables administrators to remotely manage network performance, find and solve network problems, and plan for network growth.

You use Cisco Unified Serviceability to configure SNMP-associated settings, such as community strings, users, and notification destinations for V1, V2c, and V3. Likewise, in the SNMP configuration windows, you can apply the settings to all nodes in the cluster.

An SNMP-managed network comprises of three key components: managed devices, agents, and network management systems.

Managed device—A network node that contains an SNMP agent and resides on a managed network. Managed devices collect and store management information and make it available by using SNMP.

The first node in the Cisco Unified Presence cluster acts as the managed device.

Agent—A network-managed software module that resides on a managed device. An agent contains local knowledge of management information and translates it into a form that is compatible with SNMP.

Cisco Unified Presence uses a master agent and subagent components to support SNMP. The master agent acts as the agent protocol engine and performs the authentication, authorization, access control, and privacy functions that relate to SNMP requests. Likewise, the master agent contains a few Management Information Base (MIB) variables that relate to MIB-II. The master agent also connects and disconnects subagents after the subagent completes necessary tasks. The SNMP master agent listens on port 161 and forwards SNMP packets for Vendor MIBs.

The Cisco Unified Presence subagent interacts with the local Cisco Unified Presence only. The Cisco Unified Presence subagents send trap and information messages to the SNMP Master Agent, and the SNMP Master Agent communicates with the SNMP trap receiver (notification destination).

Network Management System (NMS)—A SNMP management application (together with the PC on which it runs) that provides the bulk of the processing and memory resources that are required for network management. An NMS executes applications that monitor and control managed devices. Cisco Unified Communications Manager works with the following NMS:

CiscoWorks2000

HP OpenView

Third-party applications that support SNMP and Cisco Unified Presence SNMP interfaces

SNMP version 1 Support

SNMP version 1 (SNMPv1), the initial implementation of SNMP that functions within the specifications of the Structure of Management Information (SMI), operates over protocols, such as User Datagram Protocol (UDP) and Internet Protocol (IP).

The SNMPv1 SMI defines highly structured tables (MIBs) that are used to group the instances of a tabular object (that is, an object that contains multiple variables). Tables contain zero or more rows, which are indexed, so SNMP can retrieve or alter an entire row with a supported command.

With SNMPv1, the NMS issues a request, and managed devices return responses. Agents use the Trap operation to asynchronously inform the NMS of a significant event.

In Cisco Unified Serviceability, you configure SNMP v1 support in the V1/V2c Configuration window.

Related Topics

Configuring SNMP V1/V2c in Cisco Unified Serviceability

SNMP version 2c Support

As with SNMPv1, SNMPv2c functions within the specifications of the Structure of Management Information (SMI). MIB modules contain definitions of interrelated managed objects. The operations that are used in SNMPv1 are similar to those that are used in SNMPv2. The SNMPv2 Trap operation, for example, serves the same function as that used in SNMPv1, but it uses a different message format and replaces the SNMPv1 Trap.

The Inform operation in SNMPv2c allows one NMS to send trap information to another NMS and to then receive a response from the NMS.

In Cisco Unified Serviceability, you configure SNMP v2c support in the V1/V2c Configuration window.

Related Topics

Configuring SNMP V1/V2c in Cisco Unified Serviceability

SNMP version 3 Support

SNMP version 3 provides security features such as authentication (verifying that the request comes from a genuine source), privacy (encryption of data), authorization (verifying that the user allows the requested operation), and access control (verifying that the user has access to the objects requested.) To prevent SNMP packets from being exposed on the network, you can configure encryption with SNMPv3.

Instead of using community strings like SNMP v1 and v2, SNMP v3 uses SNMP users.

In Cisco Unified Serviceability, you configure SNMP v3 support in the V3 Configuration window.

Related Topics

Configuring SNMP V3 in Cisco Unified Serviceability

SNMP Community Strings and Users

SNMP Services

To support SNMP, you must use the following services, which display in the Control Center-Network Services screen in Cisco Unified Serviceability.

SNMP Master Agent

MIB2 Agent

Host Resources Agent

System Application Agent

Native Agent Adaptor

Cisco CDP Agent

Cisco Syslog Agent


Caution Stopping any SNMP service may result in loss of data because the network management system no longer monitors the Cisco Unified Communications Manager network. Do not stop the services unless your technical support team tells you to do so .

Related Topics

Understanding Feature and Network Services in Cisco Unified Serviceability

SNMP Community Strings and Users

Although SNMP community strings provide no security, they authenticate access to MIB objects and function as embedded passwords. You configure SNMP community strings for SNMP v1 and v2c only.

SNMP v3 does not use community strings. Instead, version 3 uses SNMP users. These users serve the same purpose as community strings, but users provide security because you can configure encryption or authentication for them.

In Cisco Unified Serviceability, no default community string or user exists.

Related Topics

Configuring SNMP V1/V2c in Cisco Unified Serviceability

Configuring SNMP V3 in Cisco Unified Serviceability

SNMP Traps and Informs

An SNMP agent sends notifications to NMS in the form of traps or informs to identify important system events. Traps do not receive acknowledgments from the destination whereas informs do receive acknowledgments. You configure the notification destinations by using the SNMP Notification Destination Configuration windows in Cisco Unified Serviceability.

For SNMP notifications, traps are sent immediately if the corresponding trap flags are enabled. In the case of the syslog agent, the alarms and system level log messages are sent to syslog daemon for logging. Also, some standard third-party applications send the log messages to syslog daemon for logging. These log messages are logged locally in the syslog files and are also converted into SNMP traps/notifications.

The `Syslog message generated' SNMP trap/inform message is sent to a configured trap destination.


Tip Before you configure notification destination, verify that the required SNMP services are active and running. Also, make sure that you configured the privileges for the community string/user correctly.

You configure the SNMP trap destination by choosing SNMP > V1/V2 > Notification Destination or SNMP > V3> Notification Destination in Cisco Unified Serviceability.


Table 6-1 comprises information about Cisco Unified Presence trap/inform parameters that you configure on the Network Management System (NMS). You can configure the values in the table below by issuing the appropriate commands on the NMS, as described in the SNMP product documentation that supports the NMS.


Note Be aware that the parameters that are listed in the table below are part of CISCO-SYSLOG-MIB.


Table 6-1 Cisco Unified Presence Trap/Inform Configuration Parameters 

Parameter Name
Default Value
Generated Traps
Configuration Recommendations

clogNotificationsEnabled

False

clogMessageGenerated

To enable trap generation, set clogNotificationsEnable to True.

clogMaxSeverity

Warning

clogMessageGenerated

When you set clogMaxSeverity to warning, a SNMP trap generates when Cisco Unified Presence applications generate a syslog message with at least a warning severity level.


SNMP Management Information Base (MIB)

SNMP allows access to Management Information Base (MIB), which is a collection of information that is organized hierarchically. MIBs comprise managed objects, which are identified by object identifiers. A MIB object, which contains specific characteristics of a managed device, comprises one or more object instances (variables).

The Simple Network Management Protocol (SNMP) extension agent resides in each Cisco Unified Presence node. Cisco Unified Presence supports the following MIBs.

CISCO-CDP-MIB

Use the Cisco Unified Presence CDP subagent to read the Cisco Discovery Protocol MIB, CISCO-CDP-MIB. This MIB enables Cisco Unified Presence to advertise itself to other Cisco devices on the network.

The CDP subagent implements the CDP-MIB. The CDP-MIB contains the following objects:

cdpInterfaceIfIndex

cdpInterfaceMessageInterval

CdpInterfaceEnable

cdpInterfaceGroup

cdpInterfacePort

CdpGlobalRun

CdpGlobalMessageInterval

CdpGlobalHoldTime

cdpGlobalLastChange

cdpGobalDeviceId

cdpGlobalDeviceIdFormat

cdpGlobalDeviceIdFormatCpd

SYSAPPL-MIB

Use the System Application Agent to get information from the SYSAPPL-MIB, such as installed applications, application components, and processes that are running on the system.

System Application Agent supports the following object groups of SYSAPPL-MIB:

sysApplInstalled

sysApplRun

sysApplMap

MIB-II

Use MIB2 agent to get information from MIB-II. The MIB2 agent provides access to variables that are defined in RFC 1213, such as interfaces, IP, and so on, and supports the following groups of objects:

system

interfaces

at

ip

icmp

tcp

udp

snmp

HOST-RESOURCES MIB

Use Host Resources Agent to get values from HOST-RESOURCES-MIB. The Host Resources Agent provides SNMP access to host information, such as storage resources, process tables, device information, and installed software base. The Host Resources Agent supports the following groups of objects:

hrSystem

hrStorage

hrDevice

hrSWRun

hrSWRunPerf

hrSWInstalled

CISCO-SYSLOG-MIB

The system supports trap functionality only. The Cisco Syslog Agent supports only the following objects of CISCO-SYSLOG-MIB:

clogNotificationsSent

clogNotificationsEnabled

clogMaxSeverity

clogMsgIgnores

clogMsgDrops

Related Topics

SNMP Traps and Informs

Vendor-Specific MIBs

The following MIBs exist on various Cisco MCS, depending on vendor and model number. To query these MIBS, you can use the standard MIB browsers that are developed by the hardware vendors; for example, HP Systems Insight Manager (SIM) and IBM Director Server+Console. For information about using the MIB browsers, refer to the documentation that the hardware vendor provides.

To review the vendor-specific MIB information, see the following tables:

Table 6-2—Describes supported IBM MIBs

Table 6-3—Describes supported HP MIBs

Table 6-2 IBM MIBs 

MIB
OID
Description
Supported for browsing only

IBM-SYSTEM-HEALTH-MIB

1.3.6.1.4.1.2.6.159.1.1.30

Provides temperature, voltage, and fan status

IBM-SYSTEM-ASSETID-MIB

1.3.6.1.4.1.2.6.159.1.1.60

Provides hardware component asset data

IBM-SYSTEM-LMSENSOR-MIB

1.3.6.1.4.1.2.6.159.1.1.80

Provides temperature, voltage, and fan details

IBM-SYSTEM-NETWORK-MIB

1.3.6.1.4.1.2.6.159.1.1.110

Provides Network Interface Card (NIC) status

IBM-SYSTEM-MEMORY-MIB

1.3.6.1.4.1.2.6.159.1.1.120

Provides physical memory details

IBM-SYSTEM-POWER-MIB

1.3.6.1.4.1.2.6.159.1.1.130

Provides power supply details

IBM-SYSTEM-PROCESSOR-MIB

1.3.6.1.4.1.2.6.159.1.1.140

Provides CPU asset/status data

Supported for system traps

IBM-SYSTEM-TRAP

1.3.6.1.4.1.2.6.159.1.1.0

Provides temperature, voltage, fan, disk, NIC, memory, power supply, and CPU details

IBM-SYSTEM-RAID-MIB

1.3.6.1.4.1.2.6.167.2

Provides RAID status


Table 6-3 HP MIBs 

MIB
OID
Description
Supported for browsing and system traps

CPQSTDEQ-MIB

1.3.6.1.4.1.232.1

Provides hardware component configuration data

CPQSINFO-MIB

1.3.6.1.4.1.232.2

Provides hardware component asset data

CPQIDA-MIB

1.3.6.1.4.1.232.3

Provides RAID status/events

CPQHLTH-MIB

1.3.6.1.4.1.232.6

Provides hardware components status/events

CPQSTSYS-MIB

1.3.6.1.4.1.232.8

Provides storage (disk) systems status/events

CPQSM2-MIB

1.3.6.1.4.1.232.9

Provides iLO status/events

CPQTHRSH-MIB

1.3.6.1.4.1.232.10

Provides alarm threshold management

CPQHOST-MIB

1.3.6.1.4.1.232.11

Provides operating system information

CPQIDE-MIB

1.3.6.1.4.1.232.14

Provides IDE (CD-ROM) drive status/events

CPQNIC-MIB

1.3.6.1.4.1.232.18

Provides Network Interface Card (NIC) status/events


SNMP Configuration Checklist

Table 6-4 provides an overview of the steps for configuring SNMP.

Table 6-4 SNMP Configuration Checklist 

Configuration Steps
Related Procedures and Topics

Step 1 

Install and configure the SNMP NMS.

SNMP product documentation that supports the NMS

Step 2 

In the Control Center—Network Services window, verify that the system started the SNMP services.

SNMP Services

Understanding Feature and Network Services in Cisco Unified Serviceability

Step 3 

If you are using SNMP v1/v2c, configure the community string.

Configuring a Community String

Step 4 

If you are using SNMP v3, configure the SNMP user.

Configuring an SNMP User

Step 5 

Configure the notification destination for traps or informs.

For SNMP v1/v2c—Configuring a Notification Destination for SNMP V1/V2c

For SNMP v3—Configuring a Notification Destination for SNMP V3

SNMP Traps and Informs

Step 6 

Configure the system contact and location for the MIB2 system group.

Configuring the MIB2 System Group

Step 7 

Restart the Master Agent service.

SNMP Services

Understanding Feature and Network Services in Cisco Unified Serviceability

Step 8 

On the NMS, configure the Cisco Unified Communications Manager trap parameters.

SNMP Traps and Informs

SNMP product documentation that supports the NMS

Troubleshooting SNMP

Review this section for troubleshooting tips.

Make sure that all of the feature and network services are running.

Problem   Cannot poll any MIBs from the system

This condition means that the community string or the snmp user is not configured on the system or they do not match with what is configured on the system. By default, no community string or user is configured on the system.

Solution   

Check whether the community string or snmp user is properly configured on the system by using the SNMP configuration windows.

Problem   Cannot receive any notifications from the system

This condition means that the notification destination is not configured correctly on the system.

Solution   

Verify that you configured the notification destination properly in the Notification Destination (V1/V2c or V3) Configuration window.

Related Topics

SNMP Services