whichSwitch Documentation

Table of Contents

Port Analyzer Application


To download current or previous versions of whichSwitch visit our download page.


Once you have downloaded the dmg file, it can normally be found in your Downloads folder.

Step 1

whichSwitch-dmgMount the dmg file that you downloaded.

Step 2


Drag app icon into application folder

Then drag and drop the application into the application folder.

Step 3

The first time you run whichSwitch you may be prompted to run a configuration script.  This script will give whichSwitch the permission it needs to run your network card in “promiscuous” mode.  Running in this mode allows the software to accept pacts (like CDP and LLDP packets) that are not explicitly destine for your computer.  Without these privileges whichSwitch will not be able to capture the packets it needs to work correctly.

User Interface


whichSwitch Main Window

The user interface has 3 primary sections to it.  The session column, the packet column, and the details column.  It has a basic layout that will feel familiar to anyone that has used iTunes, Apple mail, and the like.

  • Session – You can create, rename, and delete discovery sessions in this column
  • Packet – You will see a list of CDP/LLDP packets captured during the specific session in this column
  • Details – Here, important content from the CDP/LLDP packets captured are displayed.  Information like VLAN, Port ID, Switch name, Switch IP, etc. are found in this column.

Launch a Session


Start a new session: Select “+”, Pick the interface, click start.

To launch a session:

  • click on the “+” symbol in the lower left corner of the window.
  • In the new window select the interface you wish to capture traffic on
  • click start.
  • The capture process will begin, and if CDP or LLDP is enabled on the network port you are connected to, you will see packets captured within a minute.

Edit Session Names


Edit your session name by clicking on the current name.

To edit the session name:

  • Select the session in the sessions window.
  • Click on the session name two times… slowly.
  • You will get a cursor in the name space
  • You are now able to rename the session to something more meaningful.
  • Click outside of the cursor area to save the name change

Delete Unwanted Sessions


Delete an old session: Select old session, click “-“, click “Delete”.

To delete an old unwanted session:

  • Select the session that you want to delete
  • Click on the “-” in the lower left corner of the whichSwitch application window.
  • When prompted, confirm that you wish to delete the item.

View List of Captured CDP/LLDP Packets


Packets are named with the format: “Protocol” – “Switch Name”: “Port ID”

To view packets captured during a session:

  • Select a session in the sessions column.
  • In the next column you will see a list of all the CDP and LLDP packets that where captured during that session.
  • The packets are named after
    • the type of packet they are
    • the name of the switch that the packet came from
    • then the port on that switch that the packet came from.

View the Contents of a CDP/LLDP Packet


Details include: VLAN, Port ID, Switch Name, Switch IP, etc.

To view the details of a captured packet in a session:

  • Select a packet in the packet column
  • In the details column you will see detail pulled from the CDP/LLDP packet.
  • These details may include
    • name of the switch
    • interface on that switch
    • VLAN that packet is in
    • IP address of the switch
    • make/model of the switch
    • software version of the switch
    • and more

These are all details that are contained in the CDP/LLDP packets that was sent out from the network switch that is on the other end of the physical link you are checking.  Because CDP and LLDP packets are not forwarded by managed switches the information that you see is identifying where on the network that your computer is connected at that moment.

NOTE: Not all networks have CDP or LLDP enabled.  If the feature is not enabled on the network you are checking you will not see any packets captured in the packet window for that session.

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