Proper link-speed/duplex settings for 3750 to 3400?

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Feb 19th, 2010
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I have a 3750 connected to our providors 3400.  The connection had some issues this week, where I stopped receiving input packets, although the link remained in up/up state.  Bouncing the interface did not bring it back up.  However, changing the negotiation to auto/auto did.  We then changed it back to 100/Full, since it has been operating that way for months.


What should the proper setting be for a 3750 connected to a 3400?  Would auto work better than 100/Full?


Thanks,

T.J.

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Ganesh Hariharan Fri, 02/19/2010 - 11:50
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I have a 3750 connected to our providors 3400.  The connection had some issues this week, where I stopped receiving input packets, although the link remained in up/up state.  Bouncing the interface did not bring it back up.  However, changing the negotiation to auto/auto did.  We then changed it back to 100/Full, since it has been operating that way for months.


What should the proper setting be for a 3750 connected to a 3400?  Would auto work better than 100/Full?


Thanks,

T.J.

Hi T.J,


It will work in auto negotiation as autonegotiation link partner abilities are negotiated and use a priority resolution algorithm to establish the best mode of operation but genral recommendation and best to harcode at both the end with 1000 Mbps/Full Duplex setting.


Check out the below link on auto negotiationsettings between interfaces.


http://www.cisco.com/en/US/products/hw/switches/ps700/products_tech_note09186a00800a7af0.shtml#auto_neg_valid


Hope to help !!


Ganesh.H

tjalbrecht Fri, 02/19/2010 - 11:57
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Ganesh,


I appreciate the quick response.  One issue is, my 3750 is only capable of 100/Full.  I am not sure, but I believe the providors switch may be capable of 1000/Full.  I will read over the link you sent.


Thank you,

T.J.

Amit Singh Fri, 02/19/2010 - 12:27
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Thomas,


Its better and suggested to put the devices with different transmition parameters to "auto-negotiation". This will make sure that both the devices best negotiate on a common ground as per their capabilities/characterstics.


http://en.wikipedia.org/wiki/Autonegotiation


Cheers,

-amit singh

Leo Laohoo Fri, 02/19/2010 - 16:17
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tjalbrecht wrote:


One issue is, my 3750 is only capable of 100/Full.  I am not sure, but I believe the providors switch may be capable of 1000/Full.


Thank you,

T.J.

Depends.  If you want to enjoy Gig link to your provider, the 3750 has a minimum of 2 SFP ports.

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