dot1q trunking

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Mar 27th, 2009
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Can I configure a dot1q trunk with "switchport trunk allowed vlan none" for the sole purpose of checking connectivity without passing any traffic. Do the switches just send BPDU's for the native vlan and nothing else.

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lamav Fri, 03/27/2009 - 12:23
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Why does it have to be a trunk if you just want to check connectivity?


Just connect the two ports and be done with it. Each port will be placed in vlan1.

thotsaphon Fri, 03/27/2009 - 12:29
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Don,

To make sure that what is going on. Please do a "sh interface trunk" command. Is Vlan1 still allowed?

"Remove VLAN 1 from the allowed list so you can disable VLAN 1 on any individual VLAN trunk port in order to reduce the risk of spanning-tree loops or storms. When you remove VLAN 1 from a trunk port, the interface continues to send and receive management traffic, for example, Cisco Discovery Protocol (CDP), Port Aggregation Protocol (PAgP), Link Aggregation Control Protocol (LACP), Dynamic Trunking Protocol (DTP), and VLAN Trunking Protocol (VTP) in VLAN 1."


HTH,

Toshi

dcwright Fri, 03/27/2009 - 19:05
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I'd like to do this so my tech's can make the connections (and verify the link) without the possibility of a spanning-tree change or issue.

glen.grant Sat, 03/28/2009 - 02:27
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Just make a vlan that is not being used and put both ports in that vlan and plug it in . It would be pretty safe .

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