Dell EMC Configuration Guide for the S4048T–ON System 9.14.2.4

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Fetch Dynamic MAC Entries using SNMP

Dell EMC 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 1. MIB Objects for Fetching Dynamic MAC Entries in the Forwarding DatabaseMIB 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, 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, the manager returns the integer 118.

Example of Fetching MAC Addresses Learned on the Default VLAN Using SNMP

----------------MAC Addresses on Force10 System------------------
DellEMC#show mac-address-table
VlanId   Mac Address      Type     Interface  State
1       00:01:e8:06:95:ac Dynamic  Te 1/21    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

Example of Fetching MAC Addresses Learned on a Non-default VLAN Using SNMP

In the following example, TenGigabitEthernet 1/21 is moved to VLAN 1000, a non-default VLAN. To fetch the MAC addresses learned on non-default VLANs, use the object dot1qTpFdbTable. The instance number is the VLAN number concatenated with the decimal conversion of the MAC address.

---------------MAC Addresses on Force10 System------------
DellEMC#show mac-address-table
VlanId  Mac Address        Type     Interface  State
1000    00:01:e8:06:95:ac  Dynamic  Te 1/21    Active
---------------Query from Management Station----------------
>snmpwalk -v 2c -c techpubs 10.11.131.162 .1.3.6.1.2.1.17.7.1.2.2.1

Example of Fetching MAC Addresses Learned on a Port-Channel Using SNMP

Use dot3aCurAggFdbTable to fetch the learned MAC address of a port-channel. The instance number is the decimal conversion of the MAC address concatenated with the port-channel number.

--------------MAC Addresses on Force10 System-------------------
DellEMC(conf)#do show mac-address-table
VlanId  Mac Address        Type     Interface  State
1000    00:01:e8:06:95:ac  Dynamic  Po 1       Active
-------------Query from Management Station----------------------
>snmpwalk -v 2c -c techpubs 10.11.131.162 .1.3.6.1.4.1.6027.3.2.1.1.5
SNMPv2-SMI::enterprises.6027.3.2.1.1.5.1.1.1000.0.1.232.6.149.172.1 = INTEGER: 1000
SNMPv2-SMI::enterprises.6027.3.2.1.1.5.1.2.1000.0.1.232.6.149.172.1 = Hex-STRING: 00 01 E8
06 95 AC
SNMPv2-SMI::enterprises.6027.3.2.1.1.5.1.3.1000.0.1.232.6.149.172.1 = INTEGER: 1
SNMPv2-SMI::enterprises.6027.3.2.1.1.5.1.4.1000.0.1.232.6.149.172.1 = INTEGER: 1