A virtual chassis system comprising a plurality of network nodes , said virtual chassis system being configured to manage the plurality of network nodes within the virtual chassis system so that the plurality of network nodes are viewed as a single node with a unified administration, operations and maintenance management system by external network nodes, the system comprising: one or more network interface modules operable to: receive data packets from one or more external network nodes through one or more external port interfaces ; modify the data packets to generate packets with prepended headers, wherein the prepended headers include destination chassis identifiers; transmit packets with prepended headers between a plurality of network nodes in the virtual chassis system, wherein the plurality of network nodes are operably coupled by a plurality of dedicated link aggregate groups for communicating control and addressing information defining virtual fabric links "VFLs"; at least one management module operable to: determine to assign one of the plurality of network nodes to pass thru mode, wherein said pass thru mode allows the network node to transparently forward data packets between network nodes over VFLs but the network node is not operable to receive or transmit data packets over port interfaces to or from external network nodes ; assign a pass thru chassis identifier to the one of the plurality of network nodes; and transmit a pass thru command to the one of the plurality of network nodes, wherein the pass thru command includes the pass thru chassis identifier. one or more network interface modules operable to: receive data packets from one or more external network nodes through one or more external port interfaces ; modify the data packets to generate packets with prepended headers, wherein the prepended headers include destination chassis identifiers; transmit packets with prepended headers between a plurality of network nodes in the virtual chassis system, wherein the plurality of network nodes are operably coupled by a plurality of dedicated link aggregate groups for communicating control and addressing information defining virtual fabric links "VFLs"; receive data packets from one or more external network nodes through one or more external port interfaces ; modify the data packets to generate packets with prepended headers, wherein the prepended headers include destination chassis identifiers; transmit packets with prepended headers between a plurality of network nodes in the virtual chassis system, wherein the plurality of network nodes are operably coupled by a plurality of dedicated link aggregate groups for communicating control and addressing information defining virtual fabric links "VFLs"; at least one management module operable to: determine to assign one of the plurality of network nodes to pass thru mode, wherein said pass thru mode allows the network node to transparently forward data packets between network nodes over VFLs but the network node is not operable to receive or transmit data packets over port interfaces to or from external network nodes ; assign a pass thru chassis identifier to the one of the plurality of network nodes; and transmit a pass thru command to the one of the plurality of network nodes, wherein the pass thru command includes the pass thru chassis identifier. determine to assign one of the plurality of network nodes to pass thru mode, wherein said pass thru mode allows the network node to transparently forward data packets between network nodes over VFLs but the network node is not operable to receive or transmit data packets over port interfaces to or from external network nodes ; assign a pass thru chassis identifier to the one of the plurality of network nodes; and transmit a pass thru command to the one of the plurality of network nodes, wherein the pass thru command includes the pass thru chassis identifier. <EOS>