Dell PowerEdge FX2/FX2s - Manual (Page 182)

Fetching Dynamic MAC Entries using SNMP
The Aggregator supports the RFC 1493 dot1d table for the default VLAN and the dot1q table for all other
VLANs.
NOTE: The table contains none of the other information provided by the show vlan command, such
as port speed or whether the ports are tagged or untagged.
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 18. 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 0/7,
which is a member of the default VLAN, VLAN 1. The SNMP walk returns the values for
dot1dTpFdbAddress, dot1dTpFdbPort, and dot1dTpFdbStatus.
Each object is comprised of 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 0/7, the manager returns the integer 118.
Example of Fetching Dynamic MAC Addresses on the Default VLAN
-----------------------------MAC Addresses on Dell Networking
System-------------------------------
Dell#show mac-address-table
VlanId Mac Address Type Interface State
1 00:01:e8:06:95:ac Dynamic Tengig 0/7 Active
----------------Query from Management Station----------------------
182 Simple Network Management Protocol (SNMP)