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New Member

Disabling Spanning-Tree of a port by port basis

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.

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Hall of Fame Super Blue

Re: Disabling Spanning-Tree of a port by port basis

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

2 REPLIES
Hall of Fame Super Blue

Re: Disabling Spanning-Tree of a port by port basis

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

New Member

Re: Disabling Spanning-Tree of a port by port basis

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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