IEEE8021-PFC-MIB

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Organization: IEEE 802.1 Working Group

Last Updated: 2018-06-28

Category: Quality of Service, Standard: IEEE 802

Description: IEEE 802.1 MIB for Priority-based Flow Control (PFC/802.1Qbb) managing per-priority pause frames in Data Center Bridging.

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What Is IEEE8021-PFC-MIB?

IEEE8021-PFC-MIB is a vendor-neutral IEEE 802.1 standards MIB implementing Priority-based Flow Control (PFC, IEEE 802.1Qbb), a key Data Center Bridging (DCB) enhancement allowing per-priority pause frames on Ethernet links to prevent packet loss for lossless traffic classes such as FCoE or RoCE. It exposes per-interface configuration such as link delay allowance and lossless-priority settings, along with counters for PFC pause requests sent and indications received. From a monitoring standpoint it is used to track flow-control activity and performance health at the interface level, where spikes in PFC requests/indications signal congestion or head-of-line blocking on a link, a critical software/protocol-state health indicator in converged data center fabrics. It works alongside other Data Center Bridging MIBs (e.g., ETS, DCBX) and the base IEEE 802.1Q Bridge MIB. It is typically deployed on converged/lossless Ethernet switches and NICs in data center fabrics carrying storage or high-performance computing traffic. Engineers implementing or auditing this functionality typically reference the IEEE8021-PFC-MIB RFC/standard documentation for the authoritative specification.

IPNetwork Monitor allows you to monitor SNMP objects defined in IEEE8021-PFC-MIB. Use the built-in SNMP Monitoring Browser to explore available variables, view their current values and descriptions, and select the objects you want to monitor. You can then create SNMP monitors, configure thresholds, and receive alerts when monitored values change.

Supported Devices

Data Center Bridging (DCB) / lossless Ethernet switches
converged network adapters (CNAs)
vendor-neutral, standards-based MIB, not tied to a specific manufacturer

Monitoring Examples

Polling ieee8021PfcIfTable/ieee8021PfcIfEntry for a given interface shows ieee8021PfcRequests and ieee8021PfcIndications counts; a rapidly climbing ieee8021PfcRequests value indicates the local interface is repeatedly signaling congestion to its peer, potentially causing latency for lossless traffic. The ieee8021PfcLinkDelayAllowance value helps confirm buffer sizing is adequate to prevent pause-storm packet loss during bursts. Comparing counters across ports in ieee8021PfcIfTable can pinpoint which link in a DCB fabric is the congestion bottleneck.

What Can Be Monitored

PFC pause requests sent per interface
PFC pause indications received
link delay allowance
per-priority flow control activity

Imported Objects

From IEEE8021-TC-MIB

ieee802dot1mibs

OBJECT-IDENTITY

From IF-MIB

ifEntry	OBJECT-TYPE
ifGeneralInformationGroup	OBJECT-GROUP

From SNMPv2-CONF

MODULE-COMPLIANCE
OBJECT-GROUP

From SNMPv2-MIB

systemGroup

OBJECT-GROUP

From SNMPv2-SMI

Counter32
MODULE-IDENTITY
OBJECT-TYPE
Unsigned32

How to Use in IPNetwork Monitor

Example using ieee8021PfcRequests OID:

Select a device implementing IEEE8021-PFC-MIB as the target host to create a monitor — the SNMP service should be up and running on it. Click New Monitor, then check SNMP Custom on the Favorites tab, click Next, and confirm the host. On the next page, click Select... to open the built-in SNMP MIB Browser and type ieee8021PfcRequests into the Find box to locate it in the OID tree, selecting the specific row/instance you want to monitor since this is a table column, then select it and click OK. It reports a count of the invoked PFC M_CONTROL.request primitives. On the monitor's Main parameters page you can set the target's SNMP port (default 161), credentials, polling interval, and other settings — see the SNMP Monitor help for details. On the State conditions and Alerting tabs, configure when the monitor should change state and trigger an alert; since this is a Counter32-type OID, Value bounds is the most useful condition here — trigger an alert if the counter increases sharply between polls relative to its normal baseline (in Requests), since an unexpected spike often reflects a real change in traffic or activity. Click Finish to create the monitor; you can adjust any parameter later.

OIDs

OID symbolic	OID numeric	Type	Access	Description
ieee8021PFCMib	1.3.111.2.802.1.1.21			Priority-based Flow Control module for IEEE Std 802.1Q. Unless otherwise indicated, the references in this MIB module are to IEEE Std 802.1Q. Copyright (C) IEEE (2018). This version of this MIB module is part of IEEE Std 802.1Q; see the draft itself for full legal notices.
ieee8021PfcMIBObjects	1.3.111.2.802.1.1.21.1
ieee8021PfcIfTable	1.3.111.2.802.1.1.21.1.1		not-accessible	A table of PFC information for all interfaces of a system.
ieee8021PfcIfEntry	1.3.111.2.802.1.1.21.1.1.1		not-accessible	Each entry contains information about the PFC function on a single interface.
U32 ieee8021PfcLinkDelayAllowance	1.3.111.2.802.1.1.21.1.1.1.1	Unsigned32	read-write	The allowance made for round-trip propagation delay of the link in bits. The value of this object MUST be retained across reinitializations of the management system.
C32 ieee8021PfcRequestsEx	1.3.111.2.802.1.1.21.1.1.1.2	Counter32	read-only	A count of the invoked PFC M_CONTROL.request primitives. Discontinuities in the value of this counter can occur at re-initialization of the management system, and at other times as indicated by the value of ifCounterDiscontinuityTime.
C32 ieee8021PfcIndications	1.3.111.2.802.1.1.21.1.1.1.3	Counter32	read-only	A count of the received PFC M_CONTROL.indication primitives. Discontinuities in the value of this counter can occur at re-initialization of the management system, and at other times as indicated by the value of ifCounterDiscontinuityTime.
ieee8021PfcConformance	1.3.111.2.802.1.1.21.2
ieee8021PfcCompliances	1.3.111.2.802.1.1.21.2.1
ieee8021PfcCompliance	1.3.111.2.802.1.1.21.2.1.1			The compliance statement for support by a system of the IEEE8021-PFC-MIB module.
ieee8021PfcGroups	1.3.111.2.802.1.1.21.2.2
ieee8021PfcGlobalReqdGroup	1.3.111.2.802.1.1.21.2.2.1			Objects in the global required group.

RFC description

IEEE 802.1 standard MIB for Priority Flow Control (PFC) management on Ethernet bridges, enabling per-priority pause frames.

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Download IEEE8021-PFC-MIB