Disabling Spanning-Tree of a port by port basis

Answered Question
Dec 16th, 2008
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Hi There,


Is it possible to completely disable spanning-tree on a trunk port. I have a situation were a Sun server will be connected to a trunk port and will be tagging packets with various vlan ids. I have been told that the port must have spanning-tree disabled (yes I know its madness).


I had previously thought that it was only possible to turn vlan off on a vlan by vlan basis on a switch.


Is it possible to turn spanning-tree off on an individual port basis.



Correct Answer by Jon Marshall about 8 years 3 months ago

Jim


You can effectively turn off STP for a port by using the "spanning-tree bpdufilter enable" command under the interface -


http://www.cisco.com/en/US/docs/ios/lanswitch/command/reference/lsw_s2.html#wp1014574


Do you know why you have to disable it. If it is an issue with the NIC taking 45 seconds to begin forwarding you could look to use "spanning-tree portfast trunk" which allows the trunk port to begin forwarding immmediately but still runs STP - it's like normal portfast but for trunk links. It should never really be used on switch to switch links but it is fine for servers with trunk links.


Jon

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Correct Answer
Jon Marshall Tue, 12/16/2008 - 08:02
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Jim


You can effectively turn off STP for a port by using the "spanning-tree bpdufilter enable" command under the interface -


http://www.cisco.com/en/US/docs/ios/lanswitch/command/reference/lsw_s2.html#wp1014574


Do you know why you have to disable it. If it is an issue with the NIC taking 45 seconds to begin forwarding you could look to use "spanning-tree portfast trunk" which allows the trunk port to begin forwarding immmediately but still runs STP - it's like normal portfast but for trunk links. It should never really be used on switch to switch links but it is fine for servers with trunk links.


Jon

tobin_jim@hotma... Wed, 12/17/2008 - 02:38
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Jon,


Thanks for the information. I actually already have the ports on "spanning-tree portfast trunk" but I've been told that the manufacturer guideline is for spanning-tree to be completely disabled.


I think for this case though that the portfast trunk command will be sufficient.


Thanks again.

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