ARISTA-HARDWARE-UTILIZATION-MIB

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Organization: Arista Networks, Inc.

Last Updated: 2016-05-24

Category: Vendor: Arista

Description: Arista EOS hardware resource utilization including TCAM and forwarding table capacity.

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What Is ARISTA-HARDWARE-UTILIZATION-MIB?

ARISTA-HARDWARE-UTILIZATION-MIB is an Arista Networks enterprise MIB for EOS-based switches that reports the capacity and utilization of hardware forwarding resources such as TCAM entries and hash tables used for MAC lookup, ACLs, and L3 forwarding decisions, part of the data center/campus switching technology area. It exposes a per-resource, per-feature, per-forwarding-element table of in-use, free, committed, and maximum entry counts, along with high-watermark tracking of peak utilization and the time it occurred. This is a direct hardware-status monitoring MIB: it lets operators detect when a hardware forwarding table (e.g., an ACL TCAM or MAC table) is approaching exhaustion, which would cause silent failures such as new ACL rules or MAC entries not being programmed, well before an outage occurs, and the high-watermark objects support monitoring for utilization spikes. It is a self-contained Arista-specific MIB reflecting the vendor's own hardware forwarding architecture, without dependency on standard IETF MIBs. It is deployed on Arista EOS switches in data center and campus network environments performing hardware-based packet forwarding. Engineers can download the ARISTA-HARDWARE-UTILIZATION-MIB file directly to load it into their MIB browser.

IPNetwork Monitor allows you to monitor SNMP objects defined in ARISTA-HARDWARE-UTILIZATION-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 EOS switch (data center/campus)

Monitoring Examples

An operator would poll aristaHardwareUtilizationTable/aristaHardwareUtilizationEntry indexed by aristaHardwareUtilizationResource and aristaHardwareUtilizationFeature to compare aristaHardwareUtilizationInUseEntries against aristaHardwareUtilizationMaxEntries, alerting when a TCAM resource for a specific aristaHardwareUtilizationForwardingElement is above 90% utilized. Checking aristaHardwareUtilizationHighWatermark and aristaHardwareUtilizationHighWatermarkTime would reveal whether a recent configuration change or traffic pattern caused a utilization spike that could risk exhausting hardware forwarding capacity.

What Can Be Monitored

hardware resource in-use entries
free/committed entries
maximum entries
utilization high watermark
high watermark timestamp

Imported Objects

From ARISTA-SMI-MIB

aristaMibs

OBJECT-IDENTITY

From SNMPv2-CONF

MODULE-COMPLIANCE
NOTIFICATION-GROUP
OBJECT-GROUP

From SNMPv2-SMI

Counter32
MODULE-IDENTITY
NOTIFICATION-TYPE
OBJECT-TYPE

From SNMPv2-TC

DisplayString
TimeStamp

How to Use in IPNetwork Monitor

Example using aristaHardwareUtilizationInUseEntries 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 aristaHardwareUtilizationInUseEntries 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. This MIB object represents the number of entries in the specific hardware resource that is currently consumed by a feature. 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, 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
aristaHardwareUtilizationMIB	1.3.6.1.4.1.30065.3.22			This MIB contains information about the capacity and utilization of hardware resources on Arista devices. Arista ships and supports devices which perform packet forwarding decisions in hardware. To make these forwarding decisions (L2 bridging, input and output access list, L3 forwarding based on IP destination etc.), the devices use information programmed in various hardware resources. Examples of such hardware resources are the hash table used for MAC address lookup, TCAM for destination IP lookup etc. Each of Arista's devices have different hardware resource capacity or size limits. It is extremely useful for a Network Management system to be able to query and monitor the utilization of these hardware resources. Due to unxpected network event or configuration change, it is possible that a specific hardware resource is over utilized and there is no room to program additional entries. For example, a routing mis-configuration can result in overflowing the L3 forwarding TCAM. This may be detrimental to the network operation. So it's extremely useful to monitor the utilization of the various hardware resources of a specific device. On some devices, due to hardware design considerations, several features may have to share a single hardware resource. If one feature ends up using more of the same resource, it can affect the functionality of another feature. This is another reason to have visibility into the hardware resource usage. The hardware element that makes the forwarding decision is frequently referred to as the 'Forwarding ASIC' or 'Forwarding Chip'. In this MIB document we refer to this hardware element as 'Forwarding Element'. Even though a device can have multiple forwarding elements, the information programmed in each of the forwarding element is typically the same. But there are some cases, where this is not the case. In such instances, the utilization of relevant hardware resource(s) may not be the same across all the forwarding elements. This MIB module provides the hardware capacity and utilization information for various resources in a generic manner, that's applicable to all Arista devices.
aristaHardwareUtilizationMibNotifications	1.3.6.1.4.1.30065.3.22.0
NTF aristaHardwareUtilizationAlert	1.3.6.1.4.1.30065.3.22.0.1			This notification is generated when the hardware utilization crosses the specified threshold.
aristaHardwareUtilizationMibObjects	1.3.6.1.4.1.30065.3.22.1
aristaHardwareUtilizationTable	1.3.6.1.4.1.30065.3.22.1.1		not-accessible	This table contains information about various hardware resources and their utilization.
aristaHardwareUtilizationEntry	1.3.6.1.4.1.30065.3.22.1.1.1		not-accessible	A single conceptual row containing utilization information for a specific hardware resource. There are many hardware resources on Arista devices. Each resource is identified by a name. Several 'features' can be using the same hardware resource. Every feature is identified by a name. On several platforms, we have more than one forwarding elements which is identified by a name. A single conceptual row in the hardware utilization table represents utilization of a specific hardware resource by a specific feature on the specified forwarding element. Note that it is possible to have an entry where feature and forwarding element are both empty strings. In these cases, the conceptual row describes the overall utilization for the particular hardware resource.
STR aristaHardwareUtilizationResource	1.3.6.1.4.1.30065.3.22.1.1.1.1	DisplayString	not-accessible	The name that identifies the specific hardware resource.
STR aristaHardwareUtilizationFeature	1.3.6.1.4.1.30065.3.22.1.1.1.2	DisplayString	not-accessible	The name that identifies the specific feature which is using the hardware resource in question. As noted in the description of this MIB module, multiple features can share a specific hardware resource.
STR aristaHardwareUtilizationForwardingElement	1.3.6.1.4.1.30065.3.22.1.1.1.3	DisplayString	not-accessible	The name that identifies the specific forwarding element on the device that this hardware resource belongs to. As noted in the description of this MIB module, for some features information is programmed differently across various forwarding elements. In such cases, this MIB object represents the forwarding element that corresponds to this entry's hardware resource utilization. Otherwise this MIB object will just be an empty string.
C32 aristaHardwareUtilizationInUseEntriesEx	1.3.6.1.4.1.30065.3.22.1.1.1.4	Counter32	read-only	This MIB object represents the number of entries in the specific hardware resource that is currently consumed by a feature.
C32 aristaHardwareUtilizationFreeEntries	1.3.6.1.4.1.30065.3.22.1.1.1.5	Counter32	read-only	This MIB object represents the number of free entries in the specific hardware resource.
C32 aristaHardwareUtilizationCommittedEntries	1.3.6.1.4.1.30065.3.22.1.1.1.6	Counter32	read-only	This MIB object represents the number of entries of a hardware resource that have been dedicated ('reserved') for a particular feature. When features 'request' for a specific hardware resource, entries are 'reserved' for the feature. It is possible that the actual number of entries used is less than what has been reserved for the feature.
C32 aristaHardwareUtilizationMaxEntries	1.3.6.1.4.1.30065.3.22.1.1.1.7	Counter32	read-only	This MIB object represents the maximum number of 'logical' entries that can be allocated for the given hardware resource by the specific feature (assuming it is not being shared with any other feature). Even though the raw number of maximum entries is fixed for a given hardware resource, the logical entries available to a specific feature may vary. An example: Consider a device where the width ('number of bits') of a single TCAM entry is 128. It is possible to store an IPv4 access control list (matching both source and destination addresses) using a single entry of this TCAM. But given that IPv6 addresses are 128 bits long, 2 TCAM entries will be required to store an equivalent IPv6 access control list. In this example above, the 'maximum number of entries' available for the IPv4 feature is twice the number for the IPv6 feature.
C32 aristaHardwareUtilizationHighWatermark	1.3.6.1.4.1.30065.3.22.1.1.1.8	Counter32	read-only	This MIB object represents the maximum number of entries that the specific feature has used up at any point in time. This allows the Network Management system to monitor the hardware resource utilization pattern for a given feature allowing the operator to potentially take some action.
TIM aristaHardwareUtilizationHighWatermarkTime	1.3.6.1.4.1.30065.3.22.1.1.1.9	TimeStamp	read-only	This MIB object represents the last time when a specific feature hit the high watermark (number of entries of the given hardware resource).
aristaHardwareUtilizationMibConformance	1.3.6.1.4.1.30065.3.22.2
aristaHardwareUtilizationMibCompliances	1.3.6.1.4.1.30065.3.22.2.1
aristaHardwareUtilizationMibCompliance	1.3.6.1.4.1.30065.3.22.2.1.1			The compliance statement for Arista switches that implement the ARISTA-HARDWARE-CAPACITY-MIB.
aristaHardwareUtilizationMibGroups	1.3.6.1.4.1.30065.3.22.2.2
aristaHardwareUtilizationTableGroup	1.3.6.1.4.1.30065.3.22.2.2.1			The collection of objects that provide counter information for hardware resource utilization.
aristaHardwareUtilizationNotificationsGroup	1.3.6.1.4.1.30065.3.22.2.2.2			The notification(s) generated by the system if the hardware utilization of a specific resource exceeds configured threshold.

RFC description

Monitors hardware resource capacity and utilization on Arista network devices, including TCAM, hash tables, and memory usage for forwarding decisions.

Start monitoring Arista Networks EOS switches with a free 30-day trial of IPNetwork Monitor. Import MIBs, browse SNMP OIDs, create custom SNMP monitors, configure alerts, and monitor any SNMP-enabled network device from a single console.

Download ARISTA-HARDWARE-UTILIZATION-MIB