03-07-2006 04:05 AM - edited 03-03-2019 02:09 AM
Hi all,
When the network looping occurs, what the most packets will be generated? Broadcast or unknown unicast packets?
If I want to control the number of unknown unicast packets, which storm control should be configured? Broadcast or unicast storm control?
Thanks a lot,
Nitass
03-07-2006 04:16 AM
Depending on your situation, it could be either. However, broadcast storms are more likely. It is safe to configure broadcast storm control in most situations.
Hope that helps - pls rate the post if it does.
Pareshc
03-07-2006 04:23 AM
Thanks for reply. I understood the broadcast packet and unknown unicast packet are different; broadcast packet is for ff.ff.ff.ff.ff.ff destination mac address but unknown unicast packet isnt. Is it right?
And if I want to control the number of unknown unicast packets, which storm control should be configured? It should be unicast storm control, doesnt it?
Thanks a lot,
Nitass
03-07-2006 04:25 AM
A network loop occurs primarily due to broadcast packets or unicast packets that are sent out of multiple interfaces to the same destination device.
for e.g if you had
PC1
|
Switch 1
| |
Switch 2
|
PC2
and you somehow assume that PC1 knew the exact mac address of pc2 and sent it a unicast frame, even then because STP is not running, it would cause a broadcast storm. This would be a unicast broadcast storm.
Broadcast storm control will only control packets that are designated as broadcast i.e. all 1's. If you suspect the storm is being caused by unicast packets you may have to enable unicast control.
HTH
Please rate posts that help.
Regards
Arvind
03-07-2006 04:28 AM
That is correct - if your problem is with unicast packets, broadcast storm control is not going to help you.
Hope that helps - pls rate the post if it does.
Paresh
03-07-2006 04:38 AM
Thanks for all replies.
Could you please correct me about the unknown unicast packet?
I understood that its a unicast packet which switch doesnt have MAC address in CAM table. So the switch will send it out to every interface except the incoming. Is it correct?
Thanks a lot,
Nitass
03-07-2006 04:45 AM
Sorry I forgot one more question.
And this unknown unicast packet is controlled by unicast storm control, not broadcast storm control. Is it right?
Thanks a lot,
Nitass
03-07-2006 04:59 AM
It is obvious that broadcast control will have little effect on an unknown unicast.
Regards,
Leo
03-07-2006 04:56 AM
This is correct. The switch will learn where a mac adress resides when it sees the adress as source of an ethernet datagram. Until then, the switch has no clue to where the adress is located and hence the packet is flooded to ensure delivery to the destination.
Regards,
Leo
03-07-2006 05:00 AM
Thanks for reply.
And the unknown unicast packet is also controlled by unicast storm control, not broadcast storm control, isnt it?
Thanks a lot,
Nitass
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