DELL S6000-ON User Manual

OID String

OID Name

Description

.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 S-Series 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.

The following table describes the type and number of ASICs per platform.

Table 83. ASICs by Platform

Hardware

FP

CSF

S50N, S50V

2

0

S25V, S25P, S25N

1

0

As shown in the following example, 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 

manager does not reallocate the buffer to an adjacent congested interface, which means that in some 

cases, memory is under-used.

• Dynamic buffer — this pool is shared memory that is allocated as needed, up to a configured limit. 

Using dynamic buffers provides the benefit of statistical buffer sharing. An interface requests dynamic 

buffers when its dedicated buffer pool is exhausted. The buffer manager grants the request based on 

three conditions:

– The number of used and available dynamic buffers.
– The maximum number of cells that an interface can occupy.

1066

S-Series Debugging and Diagnostics