3 Replies Latest reply: Apr 25, 2012 7:53 AM by Imran RSS

    IP Phone


      Hi All,


      In Cisco IP Phone there are 3 ports, here neglect AUX port and talking about Sw port and PC port.

      Scenario: All IP phone are given power via power adapter so no issue of PoE!! .Now my 1st IP Phone is connected with switch via Sw port and working fine ..but the PC port is get connected to 2nd IP Phone in its SW port!!   Will it works??   If yes then one can use 100 IP Phone from 1 Switch Port!!


      Clear my doubt in detail including All possiblity of VLAN......






        • 1. Re: IP Phone
          Paul Stewart  -  CCIE Security

          Yes to the first question.  You should be able to daisy chain a second phone from the first. You will need to make sure the ports don't assume separate vlans. I don't think you can get 100 phones on one switch port. I remember connecting a switch off the back of a 7960 once and had issues at about 8 mac addresses. I never thoroughly investigated it, so you might need to experiment. Bottom line is that those integrated switches were not meant for large numbers of mac addresses.

          • 2. Re: IP Phone

            Hi Paul


            Thanks for your reply. Ya by experimenting it...will provide me my answer!!

            • 3. Re: IP Phone

              We dont usually daisy chain phones as the issue that comes with that topology is similar to token ring networks. I.e. One issue with one phone somewhere down the chain will mean that the phones further down will all lose connectivity.


              Perhaps you already know this but the command:


              switchport voice vlan x

              mls qos trust dscp (or CoS)


              Will ensure that the phones are all in the voice vlan number x, and the dscp/cos markings that are tagged onto traffic by the phone to provide priority to voice traffic will be trusted (and therefore not set back to 0)