IP Addressing Issue with Workstations on UC320 w/ SF 300 Switch

[rodneypoling]

I have a UC320 with SPA 502g phones and Cisco SF 300 10/100 Switch.

We are set up with several users plugging thier workstations into the SPA502G for network connections - then the SPA502G is connected to the SF 300.

Intermittently I get an issue where the SOA 502 is functioning correctly, but the Workstation will not be able to connect to the network. What I have determined is that the Workstation does see the network connection, but is not getting an IP Address from the DHCP Server, I am running an external – MS Win Server – DHCP Server. And have configured for that in the UC320.

What is interesting is that everything will work correctly for a period of time, then this will show up without any changes having been made. I have looked at the VLAN Assignments and they remain unchanged from the working config. The network port is set to Trunk and allows both the Voice Vlan and the Native Vlan. Looking for some new ideas on what would cause this.

Thanks - Rodney

[Christopher Edgeworth]

Hi Rodney,

I'm not sure what your comfort level is working with Wireshark, a packet sniffer.  One thing you can do is install Wireshark on the PC having the problems.   Launch Wireshark and capture on the interface connected to the switch.  Pull up a command prompt:

ipconfig /release all

ipconfig /renew all

Stop the capture.  You will then want to look for DHCP messages.  You can do a filter on bootp.

You should then see the DHCP messaging:

Discover

Offer

Request

ACK

Hope this helps.

Chris

[Mario Garcia]

Sounds like the port on the switch is locked. Reset the lock and that should allow the additional MAC addresses to connect ... assuming this is causing the issue. I have seen it happen on the 300s series switches.

Sent from Cisco Technical Support iPhone App

[rodneypoling]

Thanks,  I'll give that a look the next time i see this happen.