Cisco SRST User Guide - Page 26

Limitations, Performance Impact, Prerequisites

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Limitations Chapter 1 Cisco SRST SNMP MIB Support • To retrieve the total number of SCCP call legs (EphoneCallLegs) accumulated on the SRST router, get the total number of SCCP call legs from the CCME MIB. • To monitor the SCCP phone activities, retrieve the ccmeEphoneActTable from the CCME MIB. Limitations Be aware of the following design limitations when implementing the CISCO-SRST-MIB: • Configuring objects is not provided through SNMP. • No password or encrypted objects are provided. • Objects that are not part of the CISCO-SRST-MIB are out of the scope of this MIB. • SIP phone details that cannot be seen by underlying Cisco IOS SRST layers, such as the Ethernet address, are not provided. Performance Impact The performance characteristics of the SRST SNMP module vary significantly depending on how often bulk data is requested by the SNMP managers. SNMP bulk data can consume significant CPU and DRAM resources, and even network bandwidth. We recommend that management stations are to minimize the statistical sampling intervals as much as possible. Even though CISCO-SRST-MIB objects are grouped to reduce the unnecessary bulk data that can be fetched at a burst, the Cisco IOS SNMP agent does not enforce the data volume or the frequency at which SNMP managers make requests to the SNMP agent. To reduce performance impact, the SRST gateway managers can use the traps provided by these MIBs by using asynchronous fault notification and traps to help isolate a fault. There are few leaf objects, and they are light weighted and important (specified in active Group of the MIBs). They can be sampled at relatively short intervals, which would help gather the load on the CISCO-SRST-MIB components. The Cisco IOS software supports SNMP versions 1, 2c, and 3 (SNMPv1, SNMPv2c, and SNMPv3). The SRST MIB is compliant with SNMPv2c and SNMPv3. External SNMP managers are required; they issue SNMP queries and also accept SNMP notifications and traps. The SNMP managers include tools, such as basic Scotty command line tools, HP-OpenView, SunNet managers, IBM Netview, Tivoli, NetIQ, and so on. To provide complete monitoring solutions, the SNMP managers can interface with existing Cisco IOS MIBs that address individual components and build a "schema" (or view) that helps monitor objects that suit their configuration or needs. For SRST related scenarios, the CISCO-VOICE-DIAL-CONTROL-MIB, various hardware interface MIBs, and the CISCO-CCM-MIB are available. Prerequisites The following must be configured for the CISCO-SRST-MIB to function: • Cisco CallManager Fallback must be configured on your system. 1-12 Cisco SRST SNMP MIB Release 3.4 Guide OL-7959-01

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1-12
Cisco SRST SNMP MIB Release 3.4 Guide
OL-7959-01
Chapter 1
Cisco SRST SNMP MIB Support
Limitations
•
To retrieve the total number of SCCP call legs (EphoneCallLegs) accumulated on the SRST router,
get the total number of SCCP call legs from the CCME MIB.
•
To monitor the SCCP phone activities, retrieve the ccmeEphoneActTable from the CCME MIB.
Limitations
Be aware of the following design limitations when implementing the CISCO-SRST-MIB:
•
Configuring objects is not provided through SNMP.
•
No password or encrypted objects are provided.
•
Objects that are not part of the CISCO-SRST-MIB are out of the scope of this MIB.
•
SIP phone details that cannot be seen by underlying Cisco IOS SRST layers, such as the Ethernet
address, are not provided.
Performance Impact
The performance characteristics of the SRST SNMP module vary significantly depending on how often
bulk data is requested by the SNMP managers.
SNMP bulk data can consume significant CPU and DRAM resources, and even network bandwidth. We
recommend that management stations are to minimize the statistical sampling intervals as much as
possible. Even though CISCO-SRST-MIB objects are grouped to reduce the unnecessary bulk data that
can be fetched at a burst, the Cisco IOS SNMP agent does not enforce the data volume or the frequency
at which SNMP managers make requests to the SNMP agent.
To reduce performance impact, the SRST gateway managers can use the traps provided by these MIBs
by using asynchronous fault notification and traps to help isolate a fault.
There are few leaf objects, and they are light weighted and important (specified in active Group of the
MIBs). They can be sampled at relatively short intervals, which would help gather the load on the
CISCO-SRST-MIB components.
The Cisco IOS software supports SNMP versions 1, 2c, and 3 (SNMPv1, SNMPv2c, and SNMPv3). The
SRST MIB is compliant with SNMPv2c and SNMPv3.
External SNMP managers are required; they issue SNMP queries and also accept SNMP notifications
and traps. The SNMP managers include tools, such as basic Scotty command line tools, HP-OpenView,
SunNet managers, IBM Netview, Tivoli, NetIQ, and so on.
To provide complete monitoring solutions, the SNMP managers can interface with existing Cisco IOS
MIBs that address individual components and build a “schema” (or view) that helps monitor objects that
suit their configuration or needs. For SRST related scenarios, the
CISCO-VOICE-DIAL-CONTROL-MIB, various hardware interface MIBs, and the CISCO-CCM-MIB
are available.
Prerequisites
The following must be configured for the CISCO-SRST-MIB to function:
•
Cisco CallManager Fallback must be configured on your system.