Broadcast strom Problem

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Mar 20th, 2010
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Dear All,


Right now I am facing one problem related to broadcast or Multicast strom on our network.


Suddenly Connectivity of some of the vlans are down. and after some time it;s working fine.


Networ Topology is like :


Backbone SW - 4510R   ---------- Only one Vlan Backbone Vlan

             |

             |                               

             }

             }

L3 Distribution SW  -------------   8 nos of Vlan including Backbone vlan for communicating with Backbone,

           |

           |

           }

           {

Access SWitch.


Problem is with only 3 vlans. Rest of Vlans are working fine,


pls help how to solve the problem.


Regards,

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Giuseppe Larosa Sat, 03/20/2010 - 06:44
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Hello Dipesh,


see

http://www.cisco.com/en/US/docs/switches/lan/catalyst4500/12.2/46sg/configuration/guide/bcastsup.html#wp1052688


depending on the supervisor model and IOS image  that  is running you may need


Switch(config-if)# storm-control 
broadcast
include multicast


to be able to use storm control on broadcast and multicast as noted in a recent thread


Hope to help

Giuseppe

Dipesh Patel Sat, 03/20/2010 - 06:56
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Dear Giuseppe,


It's already there.



How to identify which PC / Device is creating this broadcast?



Regards,

Ganesh Hariharan Sat, 03/20/2010 - 08:45
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Dear Giuseppe,


It's already there.



How to identify which PC / Device is creating this broadcast?



Regards,

Hi,


In order to see which host is genrating for that you need to have tools like sinffer pro which will give GUI mode for the whole LAN traffic and which host is genrating a Boardcast or multicast or any other sporious traffic inside the LAN by spamming the whole vlan traffic to a PC in which tool is installed.


and if you have configure broadcast strom on ports then by the following commands you can see the discard packets in thos interface in the switch from that you can see which host is connected to that particular ports where you are getting heavy packets are getting discarded.


Switch# show interfaces [{type1 slot/port} | {port-channel number}] counters broadcast

Switch# show interfaces [{type1 slot/port} | {port-channel number}] counters multicast

Switch# show interfaces [{type1 slot/port} | {port-channel number}] counters unicast


There is a single counter for all suppressed traffic. These commands all display the same discard count, which shows the total number of packets discarded for all three traffic storm control modes, on all interfaces or on the specified interface.


Hope to Help !!


Ganesh.H

Dipesh Patel Sat, 03/20/2010 - 09:04
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Dear all,


What should be the uper limit and lower limit

for broadcast strom control .....?


regards,

Ganesh Hariharan Sat, 03/20/2010 - 09:14
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Dear all,


What should be the uper limit and lower limit

for broadcast strom control .....?


regards,


Hi,


On each interface, a maximum threshold can be configured in bits or packets per second, or as a percentage of the interface bandwidth. If incoming traffic of the specified type exceeds its threshold during a polling interval (one second), traffic is blocked until the incoming rate drops below the configured falling interval.


Switch(config-if)# storm-control broadcast level bps 1m 500k

In the above command, we have configured storm control for broadcast traffic with a 1 Mbps rising threshold and a 500 Kbps falling threshold. Note that specifying a falling threshold is optional; if omitted, the falling threshold will default to the value of the rising threshold (effectively removing it).


show storm-control displays interfaces configured with storm control and the state of each:


Hope to help !!


Remember to rate the helpful post


Ganesh.H

Dipesh Patel Sat, 03/20/2010 - 12:34
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Dear all,


I have checked using sniffer but broadcast sent is normal 0.21 %  .


Than What could be the reason?


ls help.


Regards,

Dipesh Patel Sun, 03/21/2010 - 04:04
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Dear All,


I have checked everything but yet I am facing the problem.


I m\am clearing more by providing topology info and sh cmd info. for  your refference.


I have a doubt of broadcast but using sniffer I have not found any broadcast. It's only 0.21%.


one more thing the port on which broadcast storm control is applied is 1 Gbps and storm control thresold is 10 i.e. 10% =====> 100 Mbps. So broadcast more than 100 Mbps will be filtered. M I right ? ??????????????????????



Should we keem thresold level lower or say 1%?



Please suggest.


Regards,

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pompeychimes Mon, 03/22/2010 - 00:14
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Why do you think a storm is causing the problem? What kind of problems are you seeing?


James

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