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New Member

Odd connection problems on a 3750 switch

Hi all,

I have a strange connection problem that is occurring at random intervals.  I have a stack of three 3750s that I had to recently reload to update to c3750e-universalk9-mz.150-2.SE5.bin.  When the reload occurred a few client computers are unable to see anything on the vlan data network or get outside and sit there off on their own.  They do grab ip addresses, but on the sh interface gix/x/x they only have outgoing packets and nothing coming in.  Their cisco phones come back online and are able to see the network and make calls on the voice vlan.  And it's not every computer that is having this occur at a time it only happens to about 5 of them.  So far the only way I can get them back online is by doing an ipconfig /release and unplugging and plugging the phone back in.  Also, on show post everything comes back as passed.  Any thoughts as to what could be going on?

Thanks for any and all help.

Everyone's tags (3)
VIP Super Bronze

Odd connection problems on a 3750 switch


I suspect this issue is related to the new IOS you recently upgraded to.

Did you have any issue before upgrading your IOS?

What was the version you used before?

One the most stable IOS version that is recommend here on the forum is 12.2(55)SE7.


New Member

Odd connection problems on a 3750 switch

I also have suspected that it could be the IOS since that's the only thing that's changed to the configuration, but I wanted to check-in here and make sure before I have to take the network down again. 

I didn't have this issue before I updated.  I was using 15.0(2)SE2, but that was acting buggy with port security so I updated to SE5 and am now having something different occur.

I'll go ahead and update to 12.2(55) SE7 tonight and give that shot. Thank you for the recommendation on the IOS.

Hall of Fame Super Gold

Odd connection problems on a 3750 switch

I was using 15.0(2)SE2, but that was acting buggy

15.0(2)SE2 is one sick puppy.  It one of the buggiest IOS in the 15.0(2)SE family.  The one you are using, 15.0(2)SE5, is no princess either.  More like a spoiled prima dona who lost her marbles 10 minutes before the curtain rise.

IF you have to use 15.X, then use 15.0(2)SE4. 

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