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Cisco Bug: CSCta92535 - Request ability of phone switch to match uplink port speed to PC

Last Modified

May 30, 2011

Products (1)

  • Cisco Unified IP Phone 7900 Series

Known Affected Releases


Description (partial)


If 100MB/Full is negotiated to Sunray box connected to IP phone while uplink speed is negotiated at 1000MB/Full, this condition can cause phone buffers to overflow and impact performance on the Sunray box.


If a  sunray box is connecting at 100M/Full to the IP Phone while the IP Phone is connecting to the uplink switch at 1000M/Full. When the SUN Server sends the data to the Sunray box, the switch thinks its connected at 1000M/Full and so it sends all the data to the IP Phone at 1000M Speed, but the connection to the Sunray box on the phone  is only 100MB.  The packets gets buffered until the data is cleared and it takes times to deliver it. In some situations, we might drop packets after the buffer gets full impacting performance.


Hardset the speed and duplex on uplink swich to 100MB so it matches the speed negotiated on PC port of the phone.  Feature request is to have the phone renegotiate uplink speed down from 1000MB to 100MB if a 100MB device is connected to the PC port.
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