Buffer tuning – Dell PowerEdge FX2/FX2s User Manual

Page 276

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OID String

OID Name

Description

.1.3.6.1.4.1.6027.3.10.1.2.5.1.7

chSysPortXfpRecvTemp

OID displays the temperature of
the connected optics.

NOTE: These OIDs only
generate if you enable the
enable optic-info-
update-interval is
enabled command.

Hardware MIB Buffer Statistics

.1.3.6.1.4.1.6027.3.16.1.1.4

fpPacketBufferTable

View the modular packet buffers
details per stack unit and the
mode of allocation.

.1.3.6.1.4.1.6027.3.16.1.1.5

fpStatsPerPortTable

View the forwarding plane
statistics containing the packet
buffer usage per port per stack
unit.

.1.3.6.1.4.1.6027.3.16.1.1.6

fpStatsPerCOSTable

View the forwarding plane
statistics containing the packet
buffer statistics per COS per port.

Buffer Tuning

Buffer tuning allows you to modify the way your switch allocates buffers from its available memory and

helps prevent packet drops during a temporary burst of traffic.

The application-specific integrated circuit (ASICs) implement the key functions of queuing, feature
lookups, and forwarding lookups in hardware.
Forwarding processor (FP) ASICs provide Ethernet MAC functions, queueing, and buffering, as well as
store feature and forwarding tables for hardware-based lookup and forwarding decisions. 1G and 10G
interfaces use different FPs.

You can tune buffers at three locations

1.

CSF — Output queues going from the CSF.

2.

FP Uplink — Output queues going from the FP to the CSF IDP links.

3.

Front-End Link — Output queues going from the FP to the front-end PHY.

All ports support eight queues, four for data traffic and four for control traffic. All eight queues are
tunable.

Physical memory is organized into cells of 128 bytes. The cells are organized into two buffer pools — the
dedicated buffer and the dynamic buffer.

• Dedicated buffer — this pool is reserved memory that other interfaces cannot use on the same ASIC

or by other queues on the same interface. This buffer is always allocated, and no dynamic re-carving

takes place based on changes in interface status. Dedicated buffers introduce a trade-off. They

provide each interface with a guaranteed minimum buffer to prevent an overused and congested

interface from starving all other interfaces. However, this minimum guarantee means that the buffer

276

Debugging and Diagnostics

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