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
This MIB module provides the hardware capacity and
utilization information for various resources in a generic
manner, that's applicable to all Arista devices.