Smarts IP: Interface duplex mode set to UKNOWN or UNSPECIFIED

Products

VMware

Issue/Introduction

Symptoms:

portDuplex mode attribute is set to UNKNOWN or UNSPECIFIED but should be FULLDUPLEX or HALFDUPLEX
Smarts IP Interface duplex mode set to UKNOWN or UNSPECIFIED

Environment

VMware Smart Assurance - SMARTS

Cause

Duplex Mode will only be set if one of the following variables is supported by the SNMP Agent on the monitored device:

Devices which support the EtherLike-MIB (dot3StatsDuplexStatus: .1.3.6.1.2.1.10.7.2.1.19)

Cisco devices that support the Cisco Stack MIB (portDuplexOID: .1.3.6.1.4.1.9.5.1.4.1.1.10)

Cisco 2900XL device (c2900PortDuplexStatus: .1.3.6.1.4.1.9.9.87.1.4.1.1.32)

Some Cosine devices (csEthDuplex: .1.3.6.1.4.1.3085.3.1.3.1.1.1.5)

Some Bay devices (rcPortOperDuplex: .1.3.6.1.4.1.2272.1.4.10.1.1.13)

Some Fore devices (sec100DuplexModeOID: .1.3.6.1.4.1.326.2.3.3.1.1.3 and (sec10DuplexModeOID: .1.3.6.1.4.1.326.2.3.2.1.1.4)

Some Lucent devices (promPortDuplexState: .1.3.6.1.4.1.2167.3.6.1.1.1.9)

Resolution

If the SNMP Agent on the monitored device does not respond to any of the variables listed in the Cause statement of this solution, the DuplexMode can be forced to "Full" by setting DuplexAssumed parameter value in discovery.conf configuration file to TRUE.

Additional Information

Supporting Information concerning SNMP Duplex-Mode Discovery for Network Adapters as implemented in IP Suite

The duplex mode setting for a network adapter determines whether Performance Manager monitors the adapter for High Utilization faults:

If duplex mode is full-duplex or half-duplex, Performance Manager calculates current utilization for the adapter and monitors the adapter for High Utilization faults.
If duplex mode is unspecified, Performance Manager neither calculates current utilization for the network nor monitors the adapter for High Utilization faults.

A network adapter s duplex mode setting is specified in the DuplexMode attribute, and its duplex mode source settingthe means by which the duplex mode is determined for the adapteris specified in the DuplexSource attribute. The default value for DuplexMode is UNSPECIFIED, and the default value for DuplexSource is NONE.

Determining Duplex-Mode

Performance Manager reads the following MIBs to determine the duplex mode value for a network adapter:

Checks for a duplex mode value in the enterprise-specific MIB. If found and the value is full-duplex or half-duplex, sets DuplexMode to FULLDUPLEX or HALFDUPLEX and sets DuplexSource to ENTERPRISE_MIB. If no value is found or the found value is not understood, Performance Manager continues to the next step.
Checks for a duplex mode value in the ETHERLIKE- MIB.
If found and the value is full-duplex or half-duplex, sets DuplexMode to FULLDUPLEX or HALFDUPLEX and sets DuplexSource to ETHERLIKE_MIB. If no value is found or the found value is not understood, Performance Manager continues to the next step.
Checks for a duplex mode value in the neighbor MIB.
If found and the value is full-duplex or half-duplex, sets DuplexMode to FULLDUPLEX or HALFDUPLEX for both local and remote ports and sets DuplexSource to NEIGHBOR_MIB. If no value is found or the found value is not understood, Performance Manager continues to the next step.
Checks the value of ICF_TopologyManager::ICF-TopologyManager::DuplexAssumed.

The value of this attribute is the value of the DuplexAssumed parameter in the discovery.conf file. At this point in the search for a duplex mode setting, Performance Manager uses the DuplexAssumed value to determine the values for the network adapter s DuplexMode and DuplexSource attributes.

If the value of the duplexMode is UNSPECIFIED then the SNMP Agent is not reporting the duplex information in any of the above places.

You can set the DuplexAssumed parameter but that will simply force the PerformanceManager to set the duplex mode to the assumed value. It is not a valid representation of how the device is configured.

The Performance Manager can only report on information available from the SNMPAgent. The ENTERPRISE_MIB values looked for are vendor specific and would not pertain to anything classified as a host. For the DuplexMode to be set from the ETHERLIKE-MIB, the SNMPAgent must respond to 1.3.6.1.2.1.10.7.2.1.19.ifIndex as defined in RFC2665.

Here is the relevent portion of the ETHERLIKE-MIB definition for your reference:

-- 1.3.6.1.2.1.10.7.2.1.19
-- iso(1). org(3). dod(6). internet(1). mgmt(2). mib-2(1). transmission(10). dot3(7). dot3StatsTable(2). dot3StatsEntry(1). dot3StatsDuplexStatus(19) SYNTAX INTEGER { unknown (1), halfDuplex (2), fullDuplex (3) }

MAX-ACCESS read-only

DESCRIPTION

"The current mode of operation of the MAC entity. 'unknown' indicates that the current duplex mode could not be determined.

Management control of the duplex mode is accomplished through the MAU MIB. When an interface does not support autonegotiation, or when autonegotiation is not enabled, the duplex mode is controlled using ifMauDefaultType. When utonegotiation is supported and enabled, duplex mode is controlled using ifMauAutoNegAdvertisedBits. In either case, the currently operating duplex mode is reflected both in this object and in ifMauType.

Note that this object provides redundant information with ifMauType. Normally, redundant objects are discouraged. However, in this instance, it allows a management application to determine the duplex status of an interface without having to know every possible value of ifMauType. This was felt to be sufficiently valuable to justify the redundancy."

REFERENCE "[IEEE 802.3 Std.], 30.3.1.1.32,aDuplexStatus." ::= { dot3StatsEntry 19 }

The default SNMP Agent for a Windows (and interestingly a Solaris) host does not report this OID for any interface.

This is the most likely reason for the DuplexMode to remain UNSPECIFIED for a host.

Why is the Duplex Mode Important for IP Suite and Performance Manager

The duplex mode setting for a network adapter determines whether Performance Manager will monitor the adapter for High Utilization faults. If the duplex mode is full-duplex or half-duplex, Performance Manager will calculate current utilization for the adapter and monitor the adapter for High Utilization faults. If the duplex mode is unspecified (default setting), Performance Manager will not calculate current utilization for the network nor monitor the adapter for High Utilization faults.

The DuplexAssumed setting controls whether EMC Smarts will calculate the current utilization for all network adapters (ports or interfaces) in the topology, or only those it can determine in the associated MIBs. Valid values for this setting are TRUE and FALSE.

DuplexAssumed/TRUE: EMC Smarts will calculate current utilization for all ports and interfaces in the topology regardless of whether their duplex mode can be determined by checking the MIBs. For any port or interface whose duplex mode cannot be determined by checking the MIBs, EMC Smarts sets the port s/interface s DuplexMode attribute to FULLDUPLEX and its DuplexSource attribute to ASSUMED. The only exception is the 10 megabit (Mb) Ethernet adapter. For this adapter type, EMC Smarts sets the adapter s duplex mode attribute to HALFDUPLEX.
DuplexAssumed/FALSE: EMC Smarts will calculate only current utilization for those ports or interfaces it can determine as full-duplex or half-duplex by reading the Enterprise MIB, ETHERLIKE-MIB, and Neighbor MIB. Any port or interface having an unspecified duplex mode setting will be ignored.

CAUTION: Calculating current utilization for all ports and interfaces (DuplexAssumed/TRUE) requires considerable system resources. Ensure that your server is sized properly to accommodate this setting for the size of your environment, as described in the EMC Smarts IP Management Suite Deployment Guide. For more information about duplex mode and current utilization calculations, see the EMC Smarts IP Performance Manager User s Guide.

Many Cisco Routers (7204, 3620, 2621, 7206) have nearly all interfaces set to UNKNOWN. Certainly all hosts are no longer monitored by default for HighUtilisation! You may need to consider alternative methods to set the DuplexMode in order to manage HighUtilisation.

Related article Link Error: concerns changed to default DuplexMode behavior with versions prior to 6.0