Deployment Guide

OID String OID Name Description
NOTE: These OIDs only generate if
you enable the enable optic-
info-update-interval is
enabled command.
Hardware MIB Buer Statistics
.1.3.6.1.4.1.6027.3.27.1.4 dellNetFpPacketBuerTable View the modular packet buers details per
stack unit and the mode of allocation.
.1.3.6.1.4.1.6027.3.27.1.5 dellNetFpStatsPerPortTable View the forwarding plane statistics
containing the packet buer usage per port
per stack unit.
.1.3.6.1.4.1.6027.3.27.1.6 dellNetFpStatsPerCOSTable View the forwarding plane statistics
containing the packet buer statistics per
COS per port.
Buer Tuning
Buer tuning allows you to modify the way your switch allocates buers from its available memory and helps prevent packet drops during a
temporary burst of trac.
The application-specic 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 buering, as well as store feature and forwarding tables
for hardware-based lookup and forwarding decisions. 1G and 10G interfaces use dierent FPs.
You can tune buers 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 trac and four for control trac. All eight queues are tunable.
Physical memory is organized into cells of 128 bytes. The cells are organized into two buer pools — the dedicated buer and the dynamic
buer.
• Dedicated buer — this pool is reserved memory that other interfaces cannot use on the same ASIC or by other queues on the same
interface. This buer is always allocated, and no dynamic re-carving takes place based on changes in interface status. Dedicated buers
introduce a trade-o. They provide each interface with a guaranteed minimum buer to prevent an overused and congested interface
from starving all other interfaces. However, this minimum guarantee means that the buer manager does not reallocate the buer to an
adjacent congested interface, which means that in some cases, memory is under-used.
• Dynamic buer — this pool is shared memory that is allocated as needed, up to a congured limit. Using dynamic buers provides the
benet of statistical buer sharing. An interface requests dynamic buers when its dedicated buer pool is exhausted. The buer
manager grants the request based on three conditions:
• The number of used and available dynamic buers.
• The maximum number of cells that an interface can occupy.
• Available packet pointers (2k per interface). Each packet is managed in the buer using a unique packet pointer. Thus, each
interface can manage up to 2k packets.
You can congure dynamic buers per port on both 1G and 10G FPs and per queue on CSFs. By default, the FP dynamic buer allocation is
10 times oversubscribed. For the 48-port 1G card:
• Dynamic Pool= Total Available Pool(16384 cells) — Total Dedicated Pool = 5904 cells
Debugging and Diagnostics
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