3 Replies Latest reply: Aug 29, 2011 4:31 AM by Paul Stewart - CCIE Security RSS

    Choosing Managed Switches

    Kalpesh Devmurari

      Why should I go for unmanaged switches in setting up a LAN? Unmanaged switches are very cheaper comapred to managed ones, and also doesn't require administration. What exaclty are the differences in functioning of managed and unmanaged switches? Do they differ in how they respond to Collisions?


      Please help me to understand it. This is the question which most of the customers asked to presales/sales guys.

        • 1. Re: Choosing Managed Switches
          Scott Morris - CCDE/4xCCIE/2xJNCIE

          The concepts of collisions and basic switching functionality will be identical among the switch types.


          You'll have a DEFAULT behavior in an unmanaged switch, and that's where you'll need to look at the technical details of that particular device to see what is used.  Can it do trunking?  Likely not PAgP (Cisco proprietary) but LACP. So if you connect it to a managed switch, you'll need to know to do LACP.


          But basically, you can either edit settings or you can't.  Most switches have management to some extent.  Like a web page to even just be able to assign vlans is still technically management.  But how much management it's capable of is up to the swtich itself.





          • 2. Re: Choosing Managed Switches
            Kalpesh Devmurari

            Thanks Scot.


            Just need some more clatification about collison control, can unmanaged switches provide collision control? If we want to list out the points/features which managed switch has in comparison to unmanaged switch, what they would be? I am asking for more clarification as I got this question in interview and i got stuck at few points.

            • 3. Re: Choosing Managed Switches
              Paul Stewart  -  CCIE Security

              If by collision control, you mean CSMA/CD then yes.  It will do collision detection when in half duplex.  An unmanaged switch is no different than a managed switch in this function.  However, a managed switch will allow you to do things like set a port to full duplex or 100Mb.  With an unmanaged switch, you basically get the default configuration of a managed switch and have no ability to change it.  So with an unmanaged switch, you can't tweak Spanning-tree (or easily verify it), change port settings (other than allowing them to automagically negotiate), enable event logging, chart port usage or create vlans, .  You also can't really do QoS stuff.  Anything that requires management is lost when you switch to an unmanaged switch.