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Professional Discussions => Routing and Switching => Topic started by: LynK on March 09, 2017, 01:49:56 PM

Title: STP vs Storm Control
Post by: LynK on March 09, 2017, 01:49:56 PM
Hey guys,

Can some of you shed some light on these two topics. If I have storm control, if there a need for STP at all? I know Storm Control does not block STP packets, etc. But does it replace it?

There has got to be something I am missing here ??? ???
Title: Re: STP vs Storm Control
Post by: wintermute000 on March 09, 2017, 02:49:31 PM
Storm control mitigates flooding. It doesn't stop loops
Title: Re: STP vs Storm Control
Post by: LynK on March 09, 2017, 02:53:32 PM
but dont all l2 loops cause broadcast storms?
Title: Re: STP vs Storm Control
Post by: dlots on March 09, 2017, 03:08:02 PM
If STP isn't stopping it yes.

However not all flooding is because of loops.

I have seen a PC go crazy and just send out butt loads of broadcast traffic, and cause some real issues.
Title: Re: STP vs Storm Control
Post by: wintermute000 on March 09, 2017, 03:47:40 PM
yep good old intel nic ipv6 ND spam (seen it twice!). THe best one I saw sent the traffic to a WLC which then used multicast - unicast replication and tried to send it to all hundred WAPs as a unicast. LOL


unless you use some specific broadcast/multicast app in your network that requires silly bandwidth its usually safe to just shove a 10% limit on all standard user ports, probably safe to go lower
Title: Re: STP vs Storm Control
Post by: mlan on March 09, 2017, 04:52:46 PM
Quote from: dlots on March 09, 2017, 03:08:02 PM
I have seen a PC go crazy and just send out butt loads of broadcast traffic, and cause some real issues.

PC's, printers, phones, etc.  I recommend both bpduguard and storm-control on all your client access ports, as well as additional port-security parameters (max # of MAC's, etc.)
Title: Re: STP vs Storm Control
Post by: icecream-guy on March 10, 2017, 06:12:13 AM
Quote from: wintermute000 on March 09, 2017, 02:49:31 PM
Storm control mitigates flooding. It doesn't stop loops

3 types of flooding for storm control

broadcast
multicast
unicast


write up here

http://www.cisco.com/c/en/us/td/docs/switches/datacenter/sw/4_1/nx-os/security/configuration/guide/sec_nx-os-cfg/sec_storm.html

http://www.netcraftsmen.com/understanding-cisco-traffic-storm-control/
Title: Re: STP vs Storm Control
Post by: Nerm on March 10, 2017, 10:30:41 AM
Quote from: wintermute000 on March 09, 2017, 03:47:40 PM
yep good old intel nic ipv6 ND spam (seen it twice!). THe best one I saw sent the traffic to a WLC which then used multicast - unicast replication and tried to send it to all hundred WAPs as a unicast. LOL

Yep seen this as recently as this last summer. That network now has full storm control policies in place lol.