Configuring Broadcast Storm Control
 

Introduction

This document describes how to configure broadcast storm control on the S-Series.

Understanding How Broadcast Storm Control Works

Broadcast storm control is implemented with high and low thresholds.  The threshold implementation follows a percentage pattern. If the broadcast traffic on any Ethernet port exceeds the high threshold percentage (as represented in the following table) of the link speed, the switch discards the broadcast’s traffic until the traffic returns to the low threshold percentage or less.

Link Speed High Low
10M 20 10
100M 5 2
1000M 5 2

A higher threshold allows more broadcast packets to pass through.

SFTOS Commands

Two commands are used with broadcast storm control:

  • storm-control broadcast – Enables broadcast storm control globally.
  • show storm-control – Displays the broadcast storm control setting on the switch.

For complete syntax usage information for these commands, refer to the SFTOS Command Reference publication. 

Sample Configuration

1. Enable broadcast storm control globally:

(s50-TAC-4) (Config)#storm-control ?
broadcast                Enable/Disable storm-control     features.
flowcontrol              Enable/Disable 802.3x flow control.
(s50-TAC-4) (Config)#storm-control     broadcast

Note: To disable broadcast storm control, use the no form of the command.

2. Verify your configuration setting with the show storm-control command.

(s50-TAC-4) #show     storm-control
Broadcast Storm Recovery Mode..................     Enable
802.3x Flow Control Mode.......................     Disable

3. Use the show interface ethernet <unit/slot/port> command to see the number of packets not forwarded due to “Broadcast Storm Recovery”.  

(s50-TAC-4) #show interface ethernet 1/0/2
Type........................................... Normal
Admin Mode..................................... Enable
Physical Mode.................................. Auto
Physical Status................................ Down
Speed.......................................... 0 - None
Link Status.................................... Detach
MAC Address.................................... 0001.E8D5.A058
Total Packets Received (Octets)................ 0
Packets Received > 1522 Octets................. 0
Packets RX and TX 64 Octets.................... 0
Packets RX and TX 65-127 Octets................ 0
Packets RX and TX 128-255 Octets............... 0
Packets RX and TX 256-511 Octets............... 0
Packets RX and TX 512-1023 Octets.............. 0
Packets RX and TX 1024-1518 Octets............. 0
Packets RX and TX 1519-1522 Octets............. 0
Packets RX and TX 1523-2047 Octets............. 0
Packets RX and TX 2048-4095 Octets............. 0
Packets RX and TX 4096-9216 Octets............. 0
Total Packets Received Without Errors.......... 0
Unicast Packets Received....................... 0
Multicast Packets Received..................... 0
Broadcast Packets Received..................... 0
Total Packets Received with MAC Errors......... 0
Jabbers Received............................... 0
Fragments Received............................. 0
Undersize Received............................. 0
Alignment Errors............................... 0
FCS Errors..................................... 0
Overruns....................................... 0
Total Received Packets Not Forwarded........... 0
Local Traffic Frames........................... 0
802.3x Pause Frames Received................... 0
Unacceptable Frame Type........................ 0
Multicast Tree Viable Discards................. 0
Broadcast Storm Recovery....................... 0
CFI Discards................................... 0
Upstream Threshold............................. 0

[output omitted]

 
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