trunking between 2 2724's

Please read my post in this thread: http://forums.us.dell.com/supportforums/board/message?board.id=pc_managed&message.id=7167

It explains how to setup VLAN trunk on 27xx switches.

Cuong.

If you read the article available online and the thread I pointed you to you can see the info about how to configure the VLANs for access and trunk modes.

As to when to use access (access port belongs to only one VLAN and take in only untag and egress only untag) and when to use trunk (trunk port can belong to more then one VLANs and all VLANs must be tag on ingress and must egress tag) here are what you should consider:

• Access port is exactly as the name imply.  It is used at the access point to the network.  Meaning that it is typically used to connect to workstations and host system at the edge of the network.  It is used to connect to any equipment (or even older switches) that do not understand VLANs and cannot accept VLAN tagged packets or send VLAN tagged packets.
• Trunk port is used as the name imply.  A trunk port is used to connect two switches that support VLANs.  It is used to trunk or carry all the VLANs you wish to move between two switches across between the switches.  The trunk port will accept ONLY tagged packet and will egress ONLY tagged packets.
• There is a third type of VLAN port which is a "general" mode port.  This mode allow you to configure a hybrid trunk or access.  Typically this is not really needed but in some special case you might find a use for it.

OK so given the above explanation I think you can see how you should configure your network.  Let's take a real scenario to make it easier to understand.  Assuming that you have VLAN 10 for engineering and VLAN 20 for HR and you want all the engineers to be able to communicate with each others but you never want the engineers to connect to any computer on the HR network and you know they will NEVER share communication directly (there are lots of implication here so make sure you understand what this means - you can not communicate at all between these systems directly).  Now let's say you have engineers and HR sitting intermixed in two buildings so you have a 2724 switch A in building A and 2724 switch B in building B and you need the engineers and HR in both buildings to communicate with each others but isolated engineers from HR then you need to trunk VLAN 10 and 20 between the two switches.

• Configure all ports that are connected to your engineering workstations to be access ports on VLAN 10.  So the engineering workstations can only send untagged packets and only accept untagged packets (default state of all NICs - some NICs do support VLAN but that's beyond the scope of this discussion).
• Configure all ports that are connected to your HR workstations to be access ports on VLAN 20.
• Connect the single fiber port between the two 2724 switches (note that if you connect more then one physical link between the two switches then you must configure a LAG - link aggregation group - otherwise you will create a bridging loop and cause really bad problems on your network).
• Configure the port connecting the two switches (configure on both switch) as trunk port and make it a member of both VLAN 10 and 20.

Ok so in 2724 you have only GUI and there is no explicit concept of trunk or access but you can still configure these modes by correctly configuring the switch (again see my earlier post where I described the modes and how to configure the modes properly on the 27xx switches).

Cuong.