# [SOLVED] Cisco Series 200 Smart Switch not communicating, DHCP blocked



## buzz339 (May 30, 2011)

I have a small, simple small business network. There are 2 switches - an 8-port switch connected to my main Windows server (which is the DHCP provider for the network), and a 24-port switch which is plugged into the 8-port switch.

I replaced these switches (Dell unmanaged switches) with the Cisco 200 series smart switches (the 8-port and 26-port models). When I plug the 26-port switch into the 8-port switch, it is unable to get its DHCP address from the Windows server. Also, any device plugged into the 26-port switch cannot communicate with any other device, and all of the ethernet port lights flash at the same time at the same frequency - quite a light show!

If I plug the Windows server DIRECTLY into the 26-port switch it receives a DHCP address.

I have tried a 2nd Cisco 26-port swtich and it does the same thing, so I assume it is not a hardware issue.

What is the solution to this problem?


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## Wand3r3r (Sep 17, 2010)

*Re: Cisco Series 200 Smart Switch not communicating, DHCP blocked*

which is it? server the dhcp server or the dhcp client?

all flashing lights usually mean a defective switch. did you read the manual and try to configure the switches?


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## buzz339 (May 30, 2011)

*Re: Cisco Series 200 Smart Switch not communicating, DHCP blocked*

Windows Server is the DHCP server. Cannot see the workgroup clients, or Workgroup.

I tried the switch out of the box, and also got into the configuration but did not see any reason it should be blocking anything.


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## Wand3r3r (Sep 17, 2010)

*Re: Cisco Series 200 Smart Switch not communicating, DHCP blocked*

make sure all ports on both are set to the same default vlan.


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## buzz339 (May 30, 2011)

*Re: Cisco Series 200 Smart Switch not communicating, DHCP blocked*

Yes, vlan 1, factory default.


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## Wand3r3r (Sep 17, 2010)

*Re: Cisco Series 200 Smart Switch not communicating, DHCP blocked*

So when the server and pc is set on the same switch it works but when the pc in on one switch and the server is on the other, they don't talk? This correct?

Not familiar with that switch but you may need to set the ports connecting the two as a trunk port in the IOS


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## buzz339 (May 30, 2011)

*Re: Cisco Series 200 Smart Switch not communicating, DHCP blocked*

got a response from Cisco that worked:

"Try this, go into the first 200 series switch that is connected to the server and go to the spanning tree tab. 

Under the spanning tree tab properties, set the bridge priority to 0. This makes this switch the spanning tree root.

Try this and see if the second switch passes traffic and receives and ip address".


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## Wand3r3r (Sep 17, 2010)

*Re: Cisco Series 200 Smart Switch not communicating, DHCP blocked*

Great news. I will add that tip to my mental database.


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