DELL PC7024 User Manual

Ethernet Configuration Commands

PowerConnect switches support a variety of configuration options to 

optimize network operations. Features such as flow-control and jumbo frames 

are supported along with a variety of commands to display traffic statistics as 

well as limit the effects of network loops or other network issues.
Jumbo frame technology is employed in certain situations to reduce the task 

load on a server CPU and to transmit large amounts of data efficiently.  

Jumbo frames technology predominantly appears where certain applications 

would benefit from using a larger frame size, e.g. Network File System (NFS). 

The larger frame size eliminates some of the need for fragmentation, leading 

to greater throughput. The increase in throughput is particularly valuable on 

data center servers where the larger frame size increases efficiency of the 

system and allows processing of more requests. The PowerConnect jumbo 

frames feature extends the standard ethernet MTU (Max Frame Size) from 

1518 (1522 with VLAN header) bytes to 9216 bytes. However, any device 

connecting to the same broadcast domain should support the same or larger 

MTU.
Flow control is a mechanism or protocol used to temporarily suspend 

transmission of data to a device to avoid overloading the device receive path. 

PowerConnect switching implements the flow control mechanism defined in 

IEEE 802.3 Annexes 31A and 31B (formerly IEEE 802.3x). PowerConnect 

switching is able to transmit a MAC Control frame containing the PAUSE 

opcode to halt transmission by the device receiving the PAUSE frame 

whenever internal congestion is detected by the switching fabric.  Flow 

control is enabled by default for all ports.
Storm control allows for rate limiting of specific types of packets through the 

forwarding plane. The administrator can configure the absolute rate in 

packets-per-second for the Storm control threshold. Each classified packet 

type (broadcast, multicast, or unicast) can be enabled/disabled per port, and 

the threshold level at which Storm-Control is active is also configurable per-

port and per-type (as a percentage of interface speed). 

2CSPC4.XCT-SWUM2XX1.book  Page 399  Monday, October 3, 2011  11:05 AM