Fetch Dynamic MAC Entries using SNMPDell Networking supports the RFC 1493 dot1d table for the default VLAN and the dot1q table for all other VLANs.NOTE: The 802.1q Q-BRIDGE MIB defines VLANs regarding 802.1d, as 802.1d itself does not define them. As a switchport mustbelong a VLAN (the default VLAN or a configured VLAN), all MAC address learned on a switchport are associated with a VLAN.For this reason, the Q-Bridge MIB is used for MAC address query. Moreover, specific to MAC address query, the MAC addressindexes dot1dTpFdbTable only for a single forwarding database, while dot1qTpFdbTable has two indices — VLAN ID and MACaddress — to allow for multiple forwarding databases and considering that the same MAC address is learned on multiple VLANs.The VLAN ID is added as the first index so that MAC addresses are read by the VLAN, sorted lexicographically. The MAC addressis part of the OID instance, so in this case, lexicographic order is according to the most significant octet.Table 83. MIB Objects for Fetching Dynamic MAC Entries in the Forwarding DatabaseMIB Object OID MIB Descriptiondot1dTpFdbTable .1.3.6.1.2.1.17.4.3 Q-BRIDGE MIB List the learned unicast MACaddresses on the default VLAN.dot1qTpFdbTable .1.3.6.1.2.1.17.7.1.2. 2 Q-BRIDGE MIB List the learned unicast MACaddresses on non-defaultVLANs.dot3aCurAggFdb Table .1.3.6.1.4.1.6027.3.2. 1.1.5 F10-LINK-AGGREGATION -MIB List the learned MAC addressesof aggregated links (LAG).In the following example, R1 has one dynamic MAC address, learned off of port TenGigabitEthernet 1/1/2/1, which a member of the defaultVLAN, VLAN 1. The SNMP walk returns the values for dot1dTpFdbAddress, dot1dTpFdbPort, and dot1dTpFdbStatus.Each object comprises an OID concatenated with an instance number. In the case of these objects, the instance number is the decimalequivalent of the MAC address; derive the instance number by converting each hex pair to its decimal equivalent. For example, the decimalequivalent of E8 is 232, and so the instance number for MAC address 00:01:e8:06:95:ac is.0.1.232.6.149.172.The value of dot1dTpFdbPort is the port number of the port off which the system learns the MAC address. In this case, ofTenGigabitEthernet 1/1/2/1, the manager returns the integer 118.Example of Fetching MAC Addresses Learned on the Default VLAN Using SNMP----------------MAC Addresses on Force10 System------------------Dell#show mac-address-tableVlanId Mac Address Type Interface State1 00:01:e8:06:95:ac Dynamic Te 1/1/2/1 Active----------------Query from Management Station---------------------->snmpwalk -v 2c -c techpubs 10.11.131.162 .1.3.6.1.2.1.17.4.3.1SNMPv2-SMI::mib-2.17.4.3.1.1.0.1.232.6.149.172 = Hex-STRING: 00 01 E8 06 95 ACExample of Fetching MAC Addresses Learned on a Non-default VLAN Using SNMPIn the following example, TenGigabitEthernet 1/1/2/1 is moved to VLAN 1000, a non-default VLAN. To fetch the MAC addresses learned onnon-default VLANs, use the object dot1qTpFdbTable. The instance number is the VLAN number concatenated with the decimal conversionof the MAC address.---------------MAC Addresses on Force10 System------------Dell#show mac-address-tableVlanId Mac Address Type Interface State1000 00:01:e8:06:95:ac Dynamic Te 1/1/2/1 Active---------------Query from Management Station---------------->snmpwalk -v 2c -c techpubs 10.11.131.162 .1.3.6.1.2.1.17.7.1.2.2.1Simple Network Management Protocol (SNMP) 805
