Cisco SMB Gig switch, no connectivity when connected to ONT

jadams

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Mar 14, 2010
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ONT-----> SWITCH ----> Router (and other devices not in the scope of this thread)

Connect the router to the ONT - connectivity
Connect ONT to switch - no connectivity
Connect Router to switch - connectivity
Connect ONT to other Cisco SMB switch below it (voice vlan) - connectivity

What the heck is wrong with my first switch?
 

jadams

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Auto-MDIX issue? Did you try a crossover cable?

We did try a crossover. Had to make one, that sucked.

You guys mention some mismatch settings. The lights done even light up on the interfaces.
 
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Sep 22, 2008
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I'm going to second Brak's comment, try some other cables and retry the crossover cable, or go buy one cause it sounds like it may not have been made properly?
 

diizzy

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Some network gear simply does have connection issues/compatibility issues in my experience.
//Danne
 

jadams

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As it turned out I had to manually change the port on the switch to 100Mb Full Auto. Why would auto negotiation not work on the switch, but it would work on the router? The router has a gigabit ethernet port and does auto negotiation.
 

NetJunkie

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As it turned out I had to manually change the port on the switch to 100Mb Full Auto. Why would auto negotiation not work on the switch, but it would work on the router? The router has a gigabit ethernet port and does auto negotiation.

Because auto negotiation is part of the Gigabit Ethernet standard. It was not part of the 100Mb standard. Usually it worked...but not always. That's why you usually hard set speed and duplex for 100Mb but you don't for 1Gb. You also don't need a crossover cable for 1Gb as they detect that and will switch if needed.
 

jadams

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I'm still kind of confused. I knew that auto negotiaion and the lack of needing a crossover was apart of gigabit.

What I dont understand:

When I connect the router (pfsense gigabit) to the ONT, it works, activity immediately
When I connect the switch (gigabit) to the ONT, it didnt work, no activity at all

So I had gigabit ports on two different devices and only one successfully had connectivity via auto negotiation.
 
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