beautypg.com

LevelOne GTL-2691 User Manual

Page 267

background image

C

HAPTER

9

| Congestion Control

Storm Control

– 267 –

When traffic exceeds the threshold specified for broadcast and

multicast or unknown unicast traffic, packets exceeding the threshold

are dropped until the rate falls back down beneath the threshold.

Traffic storms can be controlled at the hardware level using Storm

Control or at the software level using

Automatic Traffic Control

which

triggers various control responses. However, only one of these control

types can be applied to a port. Enabling hardware-level storm control

on a port will disable automatic storm control on that port.

The rate limits set by this function are also used by automatic storm

control when the control response is set to rate control on the Auto

Traffic Control (Configure Interface) page.

Using both rate limiting and storm control on the same interface may

lead to unexpected results. For example, suppose broadcast storm

control is set to 5000 pps, and the rate limit is set to 200000 Kbps on a

Gigabit Ethernet port. Since 200000 Kbps is 1/5 of line speed, the

received rate will actually be 1000 Kbps, or 1/5 of the 5000 Kbps limit

set by the storm control command. It is therefore not advisable to use

both of these features on the same interface.

P

ARAMETERS

These parameters are displayed:

Interface – Displays a list of ports or trunks.

Type – Indicates interface type. (1000BASE-T, 1000BASE SFP,

10GBASE-T, 10GBASE XFP)

Unknown Unicast – Specifies storm control for unknown unicast

traffic.

Multicast – Specifies storm control for multicast traffic.

Broadcast – Specifies storm control for broadcast traffic.

Status – Enables or disables storm control. (Default: Enabled for

broadcast storm control, disabled for multicast and unknown unicast

storm control)

Rate – Threshold level as a rate; i.e., packets per second.

(Range: 500-14880000 pps; Default: Disabled for unknown unicast and

multicast traffic, 500 pps for broadcast traffic)

W

EB

I

NTERFACE

To configure broadcast storm control:

1.

Click Traffic, Storm Control.

2.

Set the interface type to Port or Trunk.

3.

Set the Status field to enable or disable storm control.