Fetch Dynamic MAC Entries using SNMP
Dell 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 must belong 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 address indexes
dot1dTpFdbTable only for a single forwarding database, while dot1qTpFdbTable has two indices —
VLAN ID and MAC address — 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 address is part of the OID
instance, so in this case, lexicographic order is according to the most significant octet.
Table 75. MIB Objects for Fetching Dynamic MAC Entries in the Forwarding Database
MIB Object OID MIB Description
dot1dTpFdbTable .1.3.6.1.2.1.17.4.3 Q-BRIDGE MIB List the learned unicast
MAC addresses on the
default VLAN.
dot1qTpFdbTable .1.3.6.1.2.1.17.7.1.2. 2 Q-BRIDGE MIB List the learned unicast
MAC addresses on non-
default VLANs.
dot3aCurAggFdb Table .1.3.6.1.4.1.6027.3.2. 1.1.5 F10-LINK-
AGGREGATION -MIB
List the learned MAC
addresses of aggregated
links (LAG).
In the following example, R1 has one dynamic MAC address, learned off of port TenGigabitEthernet
1/21/1, which a member of the default VLAN, 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 decimal equivalent of the MAC address; derive the instance number by converting
each hex pair to its decimal equivalent. For example, the decimal equivalent 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, of TenGigabitEthernet 1/21/1, 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-table
VlanId Mac Address Type Interface State
1 00:01:e8:06:95:ac Dynamic Te 1/21/1 Active
----------------Query from Management Station----------------------
>snmpwalk -v 2c -c techpubs 10.11.131.162 .1.3.6.1.2.1.17.4.3.1
SNMPv2-SMI::mib-2.17.4.3.1.1.0.1.232.6.149.172 = Hex-STRING: 00 01 E8 06 95 AC
Simple Network Management Protocol (SNMP) 889