3 Replies Latest reply: May 27, 2009 8:25 AM by John RSS

    Reserved VLAN ID values -- What are they used for?

    Mike.B

      Hi Guys,

       

      It's my understanding that the trunking protocols (ISL and 802.1Q) support 4094 VLANs and that two specific VLAN IDs are reserved: 0 and 4095.  What are these used for?

       

      -M

       

      Message was edited by: Mike.B -- grammar and clarification

         
        • 1. Re: Reserved VLAN ID values -- What are they used for?
          ciscoskeemz

          Hey Mike,

           

          Great questions. They are both for system use. 4095 is used for some kind of internal use, but i've always been told to look at it sort of like a trash can. All traffic destined for 4095 is discarded. 0 is user priority data. VLAN 0 packets should carry an 802.1p priority but otherwise should be handled as untagged packets

           

          again, i'll leave to the experts for the truly detailed explantion

          • 2. Re: Reserved VLAN ID values -- What are they used for?
            John

            I found this from the webpage http://kb.vmware.com/selfservice/viewContent.do?externalId=1004127&sliceId=1

             

             

             

            Configuration within the Virtual Infrastructure Client

            To configure this within the Virtual Infrastructure Client:

            1. Highlight the ESX Server host
            2. Click Configuration > Networking > Properties.
            3. Highlight the virtual switch in the Ports tab.
            4. Click Edit.
            5. Click the General tab.
            6. Type a value of 0 or NONE in the VLAN ID field. This indicates that VLAN Tagging is off.
            7. Click the NIC Teaming tab.
            8. From the Load Balancing dropdown, choose Route based on originating virtual port ID
            9. Verify that there is at least one network adapter listed under ActiveAdapters

            To perform VLAN configuration and verification via command line:

            • Run the following command:

              esxcfg-vswitch –l

              The results appear similar to:
            Switch Name   Num Ports  Used Ports  Configured Ports  MTU    Uplinks
            
            vSwitch0      64         5          64               1500   vmnic3,vmnic1
            
            PortGroup Name     VLAN ID  Used Ports  Uplinks
            
            VM Network         0         0          vmnic1,vmnic3
            
            Service Console    0        1          vmnic1,vmnic3
            
            Switch Name   Num Ports  Used Ports  Configured Ports  MTU    Uplinks
            
            vSwitch2      64         8          64               1500   vmnic2,vmnic0
            
            PortGroup Name     VLAN ID  Used Ports  Uplinks
            
            VMkernel           0         1         vmnic0,vmnic2
            
            Service Console 2  0         1          vmnic0,vmnic2
            
            Production         0         2          vmnic0,vmnic2
            
            • If the VLAN ID is missing or incorrect, correct the VLAN ID value with the following command: 

              esxcfg-vswitch -v <VLAN> -p “Service Console” vSwitch0
            • 3. Re: Reserved VLAN ID values -- What are they used for?
              John

              Found this as well, not sure how accurate it is.

               

               

              VLAN 0/None" are for untagged packets, usually designated mangement VLAN, and is often VLAN 1.

               

              "VLAN 4095" only exists within a VMware ESX environment, and is for Guest tagging. In other words, the packet is given to the Guest OS without the vSwitch stripping off the VLAN tag, allowing the Guest OS to strip it off and manage it. Allows for more than 4 VLANs to be presented to the Guest OS