ARISTA-PFC-MIB

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Organization: Arista Networks, Inc.

Last Updated: 2014-08-15

Category: Vendor: Arista

Description: Arista EOS priority-based flow control (PFC) configuration and per-priority statistics.

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What Is ARISTA-PFC-MIB?

ARISTA-PFC-MIB is a proprietary Arista Networks module extending the standards-based IEEE8021-PFC-MIB with per-class-of-service detail for IEEE 802.1Qbb Priority-based Flow Control on Arista switches, a mechanism used in lossless Ethernet fabrics such as those carrying FCoE or RoCE traffic. It exposes a per-interface, per-priority table of PFC pause frame requests and indications. This is a performance/congestion monitoring module: rising PFC counters on a given priority reveal that a specific traffic class is experiencing backpressure, which can signal downstream congestion or a misconfigured lossless-traffic class. It has an explicit and notable dependency on the standard IEEE8021-PFC-MIB, which it extends rather than replaces. It is deployed on Arista data center switches running converged/lossless Ethernet fabrics where priority flow control is enabled for storage or RDMA traffic. Engineers can download the ARISTA-PFC-MIB file directly to load it into their MIB browser.

IPNetwork Monitor allows you to monitor SNMP objects defined in ARISTA-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

Arista Networks EOS switch (data center/lossless Ethernet fabric)

Monitoring Examples

An operator would poll aristaPfcPriorityTable, indexed by aristaPfcIfIndex and aristaPfcPriorityIndex, reading aristaPfcPriorityRequests and aristaPfcPriorityIndications to see how often PFC pause frames were sent or received for a given priority class on an interface. A steadily climbing aristaPfcPriorityIndications count on a specific priority would indicate that downstream congestion is repeatedly triggering flow-control pauses for that traffic class, potentially causing latency spikes for storage or RDMA applications relying on lossless delivery.

What Can Be Monitored

per-priority PFC pause requests
per-priority PFC pause indications
per-interface flow control activity by class of service

Imported Objects

From ARISTA-SMI-MIB

aristaMibs

OBJECT-IDENTITY

From IF-MIB

InterfaceIndex

From SNMPv2-CONF

MODULE-COMPLIANCE
OBJECT-GROUP

From SNMPv2-SMI

Counter64
Integer32
MODULE-IDENTITY
OBJECT-TYPE

From SNMPv2-TC

TEXTUAL-CONVENTION

How to Use in IPNetwork Monitor

Example using aristaPfcPriorityRequests OID:

Select an Arista Networks EOS switch 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 aristaPfcPriorityRequests 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 with this priority class asserted. 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 Counter64-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
aristaPfcMIB	1.3.6.1.4.1.30065.3.11			Extensions for managing IEEE 802.1Qbb Priority-based Flow Control on Arista devices. This module extends IEEE8021-PFC-MIB by providing per class-of-service information for the supported Arista platforms.
aristaPfc	1.3.6.1.4.1.30065.3.11.1
aristaPfcPriorityTable	1.3.6.1.4.1.30065.3.11.1.1		not-accessible	This table contains the per class-of-service priority-flow-control information of an interface.
aristaPfcPriorityEntry	1.3.6.1.4.1.30065.3.11.1.1.1		not-accessible	A list of attributes of each ingress class-of-service of an interface.
NUM aristaPfcIfIndex	1.3.6.1.4.1.30065.3.11.1.1.1.1	InterfaceIndex	not-accessible	The interface identified by a particular value of this index is the same interface as identified by the same value of ifIndex.
ARI aristaPfcPriorityIndex	1.3.6.1.4.1.30065.3.11.1.1.1.2	AristaPfcCOSIndex	not-accessible	The Ethernet class-of-service index for accessing the per-priority information of an interface.
C64 aristaPfcPriorityRequestsEx	1.3.6.1.4.1.30065.3.11.1.1.1.3	Counter64	read-only	A count of the invoked PFC M_CONTROL.request primitives with this priority class asserted. 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.
C64 aristaPfcPriorityIndications	1.3.6.1.4.1.30065.3.11.1.1.1.4	Counter64	read-only	A count of the received PFC M_CONTROL.indication primitives with this priority class asserted. 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.
aristaPfcConformance	1.3.6.1.4.1.30065.3.11.2
aristaPfcCompliances	1.3.6.1.4.1.30065.3.11.2.1
aristaPfcCompliance	1.3.6.1.4.1.30065.3.11.2.1.1			The compliance statement for Arista switches that support Priority Flow Control (PFC).
aristaPfcGroups	1.3.6.1.4.1.30065.3.11.2.2
aristaPfcGroup	1.3.6.1.4.1.30065.3.11.2.2.1			The group of required PFC objects.

RFC description

Extensions for managing IEEE 802.1Qbb Priority-based Flow Control on Arista devices with per class-of-service information.

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Download ARISTA-PFC-MIB