Retrieve the Dynamic CAM Information with SNMP

Cisco

SNMP Cisco MIB

Before using the information in this document, ensure that you meet the following prerequisites: - Understand how to get VLANs from a Catalyst switch via SNMP - Understand how to use Community String Indexing with SNMP - General use of SNMP get and walk commands

• The BRIDGE−MIB
• From the BRIDGE−MIB, which is extracted from RFC 1493 , you can use the dot1dTpFdbAddress from the dot1dTpFdbTable, where the value is equal to 3 or learned, to determine what Media Access Control (MAC) addresses are in the forwarding table on the switch. This value is stored as a unicast MAC address for which the bridge has forwarding and/or filtering information. These MAC address values alone do not mean much and can produce a lot of data. Therefore, you need to count the number of entries and store that count value, based on a dot1dTpFdbStatus (.1.3.6.1.2.1.17.4.3.1.3) equal to learned (value of 3).

Note: The BRIDGE−MIB uses community string indexing to access a particular instance of the MIB as described in SNMP Community String Indexing.