Q. What MIBs can I use to monitor CPU utilization on Force10 switches?

A. Use the private FORCE10-CHASSIS-MIB:

  • For the E-Series, the MIB file is f10-chassis.mib.
  • For the C-Series, the MIB file is f10-cs-chassis.mib.
  • For the S-Series, the MIB file is f10-ss-chassis.mib.

Force10 MIBs can be obtained in .zip or .tar format from the Documentation tab of the iSupport website.

The three relevant objects for the C-Series and E-Series are chRpmCpuUtil5Sec, chRpmCpuUtil11Sec, and chRpmCpuUtil15Sec. The full paths are:




The three equivalent objects for the S-Series are chStackUnitCpuUtil5Sec, chStackUnitCpuUtil11Sec, and chStackUnitCpuUtil15Sec.

Q. What MIBs can I use to monitor memory utilization?

A. Use the chRpmMemUsageUtil object in the FORCE10-CHASSIS-MIB, in the path described above. The equivalent object for the S-Series is chStackUnitMemUsageUtil.

The subject of monitoring CPU and memory utilization is covered in detail in the tech tip Collecting CPU and Memory Utilization from Force10 Switches Using SNMP.

Q. How can I get a per-VLAN list of all the ports that are members of that VLAN?

A. The Q-BRIDGE MIB provides a table per VLAN of the physical (bitmask) ports configured to be a member of the VLAN, even if the port has not learned any MAC-table entries per port/VLAN. Here is an example of how to use the following object IDs (OIDs):

Q-BRIDGE-MIB::dot1qVlanFdbId.0.1107787779 = Gauge32: 3
Q-BRIDGE-MIB::dot1qVlanFdbId.0.1107787874 = Gauge32: 98
Q-BRIDGE-MIB::dot1qVlanFdbId.0.1107787875 = Gauge32: 99
Q-BRIDGE-MIB::dot1qVlanFdbId.0.1107791870 = Gauge32: 4094
Q-BRIDGE-MIB::dot1qVlanCurrentEgressPorts.0.1107787779 = Hex-STRING:
Q-BRIDGE-MIB::dot1qVlanStaticEgressPorts.1107787779 = Hex-STRING:

Any port-channel members of the VLAN are excluded from this hex-string encoded list. However, the Force10 Enterprise Link Aggregation MIB does support the ability to see MAC-table entries per port/VLAN for port-channel interfaces. This information is dependent on dynamic forwarding state, not the port-channel/VLAN configuration.

Q. Why would my SNMP graphing tool display a spike in the interface counters?

A. Force10 implements VLAN counters as dynamically cumulative. Other vendors implement counters as incremental. Thus, if an interface is removed from a VLAN or if counters are cleared on a member interface, the output of the show interface vlan vlan-number command will display a lower number of packets. Rebooting a line card resets the packet counter to 0.

Q. How can I use SNMP to see what MAC addresses are learned on a port-channel?

A. Use the Force10 Enterprise Link Aggregation MIB to see the MAC addresses learned on a port-channel interface. In addition, you can use the Q-BRIDGE MIB to see the MAC address assigned to each member physical interface.

Q. Why I am seeing SNMP authentication failure syslog messages - %SNMP-3-SNMP_AUTH_FAIL: SNMP Authentication failure for SNMP request?

A. When you have configured an access list for limiting SNMP gets to select number of hosts, this message may be indicating that your switch has been scanned or is under a security threat. In earlier versions of FTOS, this message also reported a community string authentication failure. In later versions of FTOS, when an SNMP ACL deny with the log ACL keyword is configured, FTOS reports %SEC-6-IPACCESS: access-list LIST_NAME denied.

Q. How do I calculate interface utilization, including IFG?

A. Use the standard MIB-II (RFC 1213) to monitor interfaces. To calculate a throughput value that includes the inter-frame gap (IFG), use the MIB-II octet counters and factor in the necessary constants.

Q. How are ifIndexes calculated?

A. The ifIndex is displayed as an integer value, which can be converted to binary. Starting from the least significant bit:

  • First 14 bits are reserved for card type.
  • Next 4 bits are reserved for actual interface type
  • Next 7 bits are port ID (starting from 1)
  • Next 5 bits are slot ID (starting from 1)
  • Next 1 bit is 0 for physical and 1 for logical
  • Next 1 bit is unused

Let's look at an example.

IF-MIB::ifIndex.67420215 = INTEGER: 67420215

10 0000001 0011 00000000110111

00000000110111 = card type.

0011 = GigE

0000001 = First port = Port 0

10 = Second slot = Slot 1

Additional Information

For further information on SNMP in FTOS, see the SNMP chapter in the FTOS Configuration Guide or the following tech tips:

For assistance, contact the Force10 Technical Assistance Center by using the Create Service Request form on the iSupport page and include as much of the above information as possible.

Toll-Free: 866-965-5800
Telephone: 408-965-5800

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