Excess Broadcast traffic on our LAN

[JockFrog]

Hi,

We have a lot of broadcast traffic on our LAN and would like to know if there is anything on our 2950 Cats that could be configured to keep this to a minimum.
We have one VLAN per site and 30+ switches around a Cat 4000 core.

Does anyone have any idea?

 

[vipergg]

If there is that much broadcaST traffic you should try to find out who and why there is so much. If you want to try and protect against broadcast storms then you can go here to see how to implement this.

http://www.cisco.com/en/US/products...figuration_guide_chapter09186a00801a6bb2.html

 

[KiscoKid]

Storm control is a good way forward but I'd be concerned about trying to fix the cause of all these broadcasts.

I note you only have one VLAN per site. You could consider deploying more VLAN's to introduce more granular LAN segmentation. Also you may want to disable any unwanted protocol stacks defined on peoples PCs.

 

[ADB100]

How big is your LAN (VLAN)? i.e. how many users/devices are in the same Layer-2 VLAN? If it's more than 500 then you should look at segmenting things off into thier own VLAN's and using Layer-3 between them

HTH

Andy

 

[JockFrog]

Hi,

I think my only option is as VIPERGG says "find the source" and act accordingly. I can locate the talkers but the switches seem to be realaying the packets. Once I know what parameters are not right I can correct them.
We have 90 servers, about 50 printers and 550 users onsite.
All cisco boxes.
I checked all the printers and de-activated all unwanted protocols etc but I still have high levels of broadcast traffic. We have BMC Dashboard and Visualis installed and its via these tools that I see the traffic.

 

[vipergg]

Clear your counters on your switches and then start looking for users that may be broadcasting a lot , all that info is in the port statistics . If it is a broadcast then yes the switch will propagate it because thats the way it works. It will be blocked at the layer 3 device . If you think it is excessive then it could possibly be some device or devices that are infected .

 

[chieftan]

If you have all those systems on a single LAN then you would be better off segmenting down using VLANs.

This will control the broadcasts better.