802.1Q trunking

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May 21st, 2008
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We have a core Avaya 882 switch that will soon be replaced with a 6513 switch. Currently the Avaya switch is connected to Avaya 330 and Cisco 3750 edge switches. I have 802.1Q trunking setup.

I was wondering about 8021Q nonnegotiate mode. With the current core Avaya switch. Should my 3750 be set to nonnegotiate? Do not see that option on the Avaya core switch. Interesting that one stack of 3750s is using nonnegotiate and an another is not. I tried to change the nonnegotiate off on the one stack but the stack uplink went down and didn't come up till I went back to nonegotiate.

When I place the 6513 as our core how do I want to setup the trunking mode from the 6513 to the 3750s.


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CriscoSystems Wed, 05/21/2008 - 09:57
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I would configure each port that you want to do trunking as "dynamic desirable." That way they'll both try to become trunk ports and neither will fight the other.

m_zabetian Wed, 05/21/2008 - 12:02
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Nonegotiate: Puts the port into permanent trunking mode but prevents the port from generating DTP frames. You must configure the neighboring port manually as a trunk port to establish a trunk link. This is useful for devices that do not support DTP.

So you should configure other side ON or Nonegotiate mode.

cef2lion2 Wed, 05/21/2008 - 12:19
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Not sure if our Avaya core 882 supports DTP. I have one stack of 3750s set for nonegotiate and the other disabled. Both stacks work. Not sure if that means the Core 882 support DTP. Do not see anything in the docs or the GUI on the 882. The running config doesn't show anything as well.

When I get the 6513 in to replace the 882. As suggested should I use dynamic or what would be the best setting for these core to building edge 3750 stacks.


CriscoSystems Wed, 05/21/2008 - 12:23
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m_zabetian raises a valid point about nonegotiate mode preventing DTP frames. If after the Avaya is gone all of your switches are Cisco then they should all be DTP compliant. However, nonegotiate would then have the added benefit of keeping DTP frames off of the link and thus saving bandwidth.

So, m_zabetian's reply has brought about in me some resipiscence yes RESIPISCENCE. I now believe that nonegotiate at both ends of the link is the right way to go.


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