CHAPTER
36-1
Cisco 7600 Series Router Cisco IOS Software Configuration Guide—12.1E
78-14064-04
36
Configuring SNMP IfIndex Persistence
This chapter describes how to configure the SNMP ifIndex persistence feature on Cisco 7600 series
routers. Release 12.1(13)E and later releases support SNMP ifIndex persistence.
This chapter consists of these sections:
• Understanding SNMP IfIndex Persistence, page 36-1
• Configuring SNMP IfIndex Persistence, page 36-1
• Configuration Examples, page 36-3
Understanding SNMP IfIndex Persistence
The SNMP ifIndex persistence feature provides an interface index (ifIndex) value that is retained and
used when the router reboots. The ifIndex value is a unique identifying number associated with a
physical or logical interface.
There is no requirement in the relevant RFCs that the correspondence between particular ifIndex values
and their interfaces be maintained when the router reboots, but many applications (for example, device
inventory, billing, and fault detection) require maintenance of this correspondence.
You can poll the router at regular intervals to correlate the interfaces to the ifIndexes, but it is not
practical to poll constantly. The SNMP ifIndex persistence feature provides permanent ifIndex values,
which eliminates the need to poll interfaces.
The following definitions are based on RFC 2233, “The Interfaces Group MIB using SMIv2.” The
following terms are values in the Interfaces MIB (IF-MIB):
• ifIndex —A unique number (greater than zero) that identifies each interface for SNMP
identification of that interface.
• ifName—The text-based name of the interface, for example, “ethernet 3/1.”
• ifDescr—A description of the interface. Recommended information for this description includes the
name of the manufacturer, the product name, and the version of the interface hardware and software.
Configuring SNMP IfIndex Persistence
These sections describe how to configure SNMP ifIndex persistence:
• Enabling and Disabling SNMP IfIndex Persistence Globally, page 36-2 (Optional)
• Enabling and Disabling SNMP IfIndex Persistence on Specific Interfaces, page 36-2 (Optional)
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