Table of Contents

SNMP

This chapter explains Simple Network Management Protocol (SNMP) as implemented by the Cisco ONS 15454 SDH.

11.1 SNMP Overview

SNMP is an application-layer communication protocol that allows network devices to exchange management information. SNMP enables network administrators to manage network performance, find and solve network problems, and plan network growth.

The ONS 15454 SDH uses SNMP to provide asynchronous event notification to a network management system (NMS). ONS SNMP implementation uses standard Internet Engineering Task Force (IETF) MIBs to convey node-level inventory, fault, and performance management information for generic read-only management of electrical, SDH, and Ethernet technologies. SNMP allows limited management of the ONS 15454 SDH by a generic SNMP manager, for example HP OpenView Network Node Manager (NNM) or Open System Interconnection (OSI) NetExpert.

The Cisco ONS 15454 SDH supports SNMP Version 1 (SNMPv1) and SNMP Version 2c (SNMPv2c). Both versions share many features, but SNMPv2c includes additional protocol operations. This chapter describes both versions and explains how to configure SNMP on the ONS 15454 SDH. Figure 11-1 illustrates a basic network managed by SNMP.

11.2 SNMP Basic Components

An SNMP-managed network consists of three primary components: managed devices, agents, and management systems. A managed device is a network node that contains an SNMP agent and resides on an SNMP-managed network. Managed devices collect and store management information and use SNMP to make this information available to management systems that use SNMP. Managed devices include routers, access servers, switches, bridges, hubs, computer hosts, and network elements such as an ONS 15454 SDH.

An agent is a software module that resides in a managed device. An agent has local knowledge of management information and translates that information into a form compatible with SNMP. The SNMP agent gathers data from the MIB, which is the repository for device parameter and network data. The agent can also send traps, or notification of certain events, to the manager. Figure 11-2 illustrates these SNMP operations.

A management system such as HP OpenView executes applications that monitor and control managed devices. Management systems provide the bulk of the processing and memory resources required for network management. One or more management systems must exist on any managed network. Figure 11-3 illustrates the relationship between the three key SNMP components.

11.3 SNMP Support

The ONS 15454 SDH supports SNMPv1 and SNMPv2c traps and get requests. The SNMP MIBs in the ONS 15454 SDH define alarms, traps, and status. Through SNMP, NMS applications can query a management agent using a supported MIB. The functional entities include Ethernet switches and SDH multiplexers.

Procedure: Set Up SNMP Support

Step 2   Click the Provisioning > SNMP tabs.

Step 3   Click Create at the bottom of the window.

The Create SNMP Trap Destination dialog box opens (Figure 11-4).

For a description of SNMP traps, see the "SNMP Traps" section.

Step 4   Type the IP address of your NMS in the IP Address field.

Step 5   Type the SNMP community name in the Community Name field.

For a description of SNMP community names, see the "SNMP Community Names" section.

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Note    The community name is a form of authentication and access control. The community name assigned to the ONS 15454 is case-sensitive and must match the community name of the NMS.

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Note    The default UDP port for SNMP is 162.

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Step 6   Set the Trap Version field to either SNMPv1 or SNMPv2.

Refer to your NMS documentation to determine whether to use SNMP version 1 (v1) or SNMP version 2 (v2).

Step 7   Set your maximum traps per second in the Max Traps per Second field.

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Note    The Max Traps per Second is the maximum number of traps per second that will be sent to the SNMP manager. If the field is set to 0, there is no maximum and all traps are sent.

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Step 8   Click OK.

SNMP settings are now configured. To view SNMP information for each node, highlight the node IP address in the Trap Destinations area of the Trap Destinations window (Figure 11-5).

11.4 SNMP Management Information Bases

A management information base (MIB) is a hierarchically organized collection of information. Network-management protocols, such as SNMP, gain access to MIBs. MIBs consist of managed objects and are identified by object identifiers.

The ONS 15454 SDH SNMP agent communicates with an SNMP management application using SNMP operations. Table 11-3 describes these messages.

A managed object (sometimes called a MIB object) is one of any specific characteristics of a managed device. Managed objects consist of one or more object instances (variables). Table 11-4 lists the IETF standard MIBs implemented in the ONS 15454 SDH SNMP agent.

The ONS 15454 SDH MIBs are included on the software CD that ships with the ONS 15454 SDH. Compile these MIBs in the following order. If you do not follow the order, one or more MIB files might not compile.

1. CERENT-GLOBAL-REGISTRY.mib

2. CERENT-TC.mib

3. CERENT-454.mib

4. CERENT-GENERIC.mib

If you cannot compile the ONS 15454 SDH MIBs, call the Technical Assistance Center (TAC). To obtain a directory of toll-free Cisco TAC telephone numbers for your country, refer to the Cisco ONS 15454 SDH Product Overview preference section.

11.5 SNMP Traps

The ONS 15454 SDH can receive SNMP requests from a number of SNMP managers and send traps to eleven trap receivers. The ONS 15454 SDH generates all alarms and events as SNMP traps.

The ONS 15454 SDH generates traps containing an object ID that uniquely identifies the alarm. An entity identifier uniquely identifies the entity that generated the alarm (slot, port, STS, VT, BLSR, STP, etc.). The traps give the severity of the alarm (critical, major, minor, event, etc.) and indicate whether the alarm is service affecting or non-service affecting. The traps also contain a date/time stamp that shows the date and time the alarm occurred. The ONS 15454 SDH also generates a trap for each alarm when the alarm condition clears.

Each SNMP trap contains eleven variable bindings for the ONS 15454 SDH, listed in Table 11-5.

The ONS 15454 SDH supports the generic and IETF traps listed in Table 11-6.

11.6 SNMP Community Names

You can provision community names for all SNMP requests from the SNMP Trap Destination dialog box in CTC. (See the "SNMP Support" section.) In effect, SNMP considers any request valid that uses a community name matching a community name on the list of provisioned SNMP trap destinations. Otherwise, SNMP considers the request invalid and drops it.

If an SNMP request contains an invalid community name, the request silently drops and the MIB variable (snmpInBadCommunityNames) increments. All MIB variables managed by the agent grant access to all SNMP requests containing a validated community name.

11.7 SNMP Remote Network Monitoring

The ONS 15454 SDH incorporates RMON to allow network operators to monitor the Ethernet cards. For more information on Ethernet RMONs, see the "Remote Monitoring Specification Alarm Thresholds" section. This feature is not apparent to the typical CTC user, because RMON interoperates with an NMS. However, with CTC you can provision the RMON alarm thresholds. CTC also monitors the five RMON groups implemented by the ONS 15454 SDH.

ONS 15454 SDH RMON implementation is based on the IETF-standard MIB Request for Comment (RFC)1757. The ONS 15454 SDH implements five groups from the standard MIB: Ethernet Statistics, History Control, Ethernet History, Alarm, and Event.

11.7.1 Ethernet Statistics Group

The Ethernet Statistics group contains the basic statistics for each monitored subnetwork in a single table named etherstats.

11.7.2 History Control Group

The History Control group defines sampling functions for one or more monitor interfaces. RFC 1757 defines the historyControlTable.

11.7.3 Ethernet History Group

The ONS 15454 SDH implements the etherHistoryTable as defined in RFC 1757, within the bounds of the historyControlTable.

11.7.4 Alarm Group

The Alarm group consists of a single alarm table. This table provides the network performance alarm thresholds for the network management application. With CTC, you can provision the thresholds in the table.

11.7.5 Event Group

The Event group consists of two tables, eventTable and logTable. The eventTable is read-only. The ONS 15454 SDH implements the logTable as specified in RFC 1757.