Abstract: Packet processing logic of a host system's virtualization manager detects packets on the ingress or the egress path to/from a virtual port having three bitmap arrays for processing packets within a virtual local area network (VLAN). The logic checks the VLAN identifier (VID) of the packet to determine, based on an offset position within the corresponding bitmap array, whether the port supports the VLAN. Both the ingress array offset position and egress array offset positions correspond to the value of the VID, and are set within the specific bitmap array during configuration of the VLAN on the port. When the VLAN is supported by the port, the logic enables the packet to be processed by the port. Otherwise, the logic discards the packet. A strip bitmap array indicates when a packet's VID should be removed prior to forwarding the packet on the egress of a port (or destination port).

Abstract: Providing a label is disclosed. A first message is transmitted to an access device where the first message includes a set of available labels. A second message is received from the access device where the second message includes a label from the set of available labels selected to be used by the access device. The set of available labels is updated to account for the label selected by the access device.

Abstract: A process is implemented in a network element of a packet data to route packets with embedded virtual local area network information and an IP header to far end addresses of virtual forwarding instances. The method receiving a frame including an embedded virtual network identifier (VNI). The VNI is looked up to identify a virtual forwarding instance (VFI), the VFI having a correlated an I-Component Service Identifier (I-SID) and an internet protocol (IP) to backbone media access control (B-MAC) table that is shared with a set of VFIs each having correlated I-SIDs. The VFI resolves an IP address of the frame to a B-MAC address using the shared IP to B-MAC resolution table and encapsulates the frame with the I-SID and B-MAC; and the frame is then sent to the remote B-MAC address.

Abstract: A plurality of data flows can be routed from a first node of the network to one or more other nodes of the network. A destination of a data packet for each data flow is determined. When the destination node of the data packet of that data flow is not adjacent to the first node, a probabilistic determination is made for a next hop of data packets of that data flow. When the destination node of the data packet of that data flow is adjacent to the first node, a priority designation is made for the next hop of data packets of that data flow as being the destination node. The next hop for data packets of the data flow is determined based on either the probabilistic determination or the priority designation.

Abstract: In a method for routing packets between a plurality of switches in a computer network, in which paths between the plurality of switches are identified as a plurality of virtual local area networks (VLANs) stored in a balancing table, a packet to be routed from a source switch to a destination switch is received. In addition, a VLAN is selected from the plurality of VLANs in the balancing table to route the packet through the computer network and the packet is routed through the selected VLAN.

Abstract: A centralized packet processor device for use in a communication system includes a plurality of physical ports to couple the centralized packet processor device to a plurality of network devices, a port manager coupled to the plurality of physical ports and configured to assign to a packet received at the centralized packet processor device a virtual port that uniquely identifies at least one of a physical port and a trunk of the network device from which the packet is received and that is used with the centralized packet processor to process the packet, and a packet processor unit coupled to the plurality of physical ports, where the packet processor is configured to process the packet using the assigned virtual port.

Abstract: Systems and methods for the management of virtual machine instances are provided. The hosted virtual machine networks are configured in a manner such that communications within the hosted virtual machine network are facilitated through a communication protocol. Illustrative embodiments of the systems and methods may be implemented on a virtual network overlaid on one or more intermediate physical networks that are used as a substrate network. Through the utilization of one or more virtual network mapping components in communication with the hosted virtual network components, communications to and from the hosted virtual networks can be processed by mapping relationships between the virtual network communication protocol and the router communication protocol. The mapping information can be provided in advance or as requested to the router components and hosted virtual network components to facilitate bi-lateral communications between the components.

Abstract: A network device is provided in a private virtual local area network (VLAN). The network device receives a packet on one of multiple private VLAN ports of the network device, and assigns a classified VLAN signature to the packet. The network device also assigns a primary VLAN signature to the packet, and stores a media access control (MAC) address and the classified VLAN signature of the packet in a single MAC address table.

Abstract: Techniques are described for forwarding packets in a VPLS using multi-homing PE routers configured in an “active-active” link topology. A router includes a control unit that forms a customer-facing multi-chassis link aggregation group (LAG) to include a plurality of active access links that couple the router and a second router to a multi-homed customer site associated with the VPLS domain. The control unit also forms a core-facing multi-chassis LAG within the VPLS domain to include a plurality of pseudowires that connect the router and other member routers of the core-facing LAG to a common remote router of the VPLS domain. The router receives layer two (L2) packets from the multi-homed customer site on one or more of the active access links and forwards the L2 packets to the remote router over one or more of the pseudowires using the core-facing multi-chassis LAG.

Abstract: A virtual private network (VPN) service is provided through a shared network infrastructure comprising interconnected provider edge (PE) devices having customer edge (CE) interfaces. Some of the CE interfaces are allocated to a VPN supporting virtual LANs. A correspondence between a CE interface and a virtual LAN is learnt on the basis of tagged frames received at this CE interface and including an identifier of this virtual LAN. The learning process permits the detection of pairs of CE interfaces which correspond to a common virtual LAN. Upon such detection, a virtual circuit is established in the shared network infrastructure between the PE devices having these CE interfaces, and subsequently used for forwarding frames including the identifier of the common virtual VLAN.

Abstract: A virtual private network (VPN) service is provided through a shared network infrastructure comprising interconnected provider edge (PE) devices having customer edge (CE) interfaces. Some of the CE interfaces are allocated to a VPN supporting virtual LANs. A correspondence between a CE interface and a virtual LAN is learnt on the basis of tagged frames received at this CE interface and including an identifier of this virtual LAN. The learning process permits the detection of pairs of CE interfaces which correspond to a common virtual LAN. Upon such detection, a virtual circuit is established in the shared network infrastructure between the PE devices having these CE interfaces, and subsequently used for forwarding frames including the identifier of the common virtual VLAN.

Abstract: A modem (for example, a modem within a cellular telephone) includes a plurality of Wireless Communication System Modem Sub-Circuits (WCSMSCs). Each WCSMSC receives a control signal generated by a corresponding one of a plurality of programmable timers. Each timer receives the same sequence of count values from a wall clock counter. A processor that controls overall modem operation can program a timer to generate a control pulse at a particular count time of the wall clock counter. The processor can also program a timer to generate a periodic control signal. The control signals output from the timers orchestrate when the various WCSMSCs start operating in the processing of a frame. By virtue of the programmability of the timers, the wall clock timer system is programmable to generate customized control signals such that frames of new and different protocols having arbitrary frame structures can be processed by the same modem/timer system.

Abstract: Techniques disclosed herein include features and methods that extend functionality of provider networks including Provider Backbone Bridges (PBB) networks. Techniques include using a portion of information within Ethernet address encapsulation headers for purposes other than identifying source and destination device addresses. The system limits a number of bits in an address header that should be considered by a provider network node when doing an address lookup in forwarding tables of a provider network node, such as by masking the portion of bits or otherwise disregarding that portion of bits during address lookup. The remaining bits in the address field(s) become free bits that can be used for a variety of application purposes, such as flow path selection. By using information fields that already exist in the Mac-In-Mac (MIM) encapsulation header, such Techniques provide additional information without increasing packet size or requiring new protocols.

Abstract: A set of virtual local area networks (VLANs) are defined from a set of nodes that comprise a data center network. A set of possible paths are determined for routing data packets from a root node to one or more other nodes of the set of nodes. A set of probabilistic values are identified for determining a path in the set of possible paths that individual data packets are to take as between the root node and a destination node specified by the individual data packet. The data packets are routed to the destination node specified by that data packet, along a path that is determined by use of the set of probabilistic values. The path may be provided by one or more VLANs.

Abstract: A system that includes multiple hosts, each running a plurality of virtual machines. The system may be, for example, a cloud computing environment in which there are services and a service coordination system that communicates with the hosts and with the services. The services include a middleware management service that is configured to maintain per-tenant middleware policy for each of multiple tenants. The middleware management service causes the middleware policy to be applied to network traffic by directing network traffic to a middleware enforcement mechanism. This middleware policy is per-tenant in that it depends on an identity of a tenant.

Abstract: The invention includes a method and apparatus for distributing flooding labels within a Multiprotocol Label Switching (MPLS) infrastructure supporting Border Gateway Protocol (BGP) Media Access Control (MAC) Virtual Private Networking (VPN).

Abstract: A system to manage data congestion in a computer network may include network devices to route data packets throughout the network. The system may also include a source node that sends data packets to any of the network devices. The system may further include a routing table at each network device that is updated by the source node, and the route the data packets are sent by any network device is based upon each respective routing table.

Abstract: A computer readable medium comprising computer readable code for data transfer. The computer readable code, when executed, performs a method. The method includes receiving, at a first Axon, an ARP request from a source host directed to a target host. The method also includes obtaining a first route from the first Axon to the second Axon, and generating a target identification corresponding to the target host. The method further includes sending an Axon-ARP request to the second Axon using the first route, and receiving an Axon-ARP reply from the second Axon, where the Axon-ARP reply includes a second route. The method further includes storing the first route in storage space on the first Axon, where the storage space is indexed by the target identification, and sending an ARP reply to the first host where the source host is configured to send a packet to the target host.

Abstract: A relay server stores a routing apparatus belonging to a VPN group to which the relay server itself belongs, a second routing object address that is an address of the routing apparatus, and the like. The relay server stores a relationship of assignment of a virtual address to the second routing object address. The virtual address is an address that does not overlap with addresses of any other apparatuses. The relay server, upon receipt of a packet from a routing session, converts a source of the packet from an actual address into the virtual address and forwards the packet to a routing object device of the relay server itself. The relay server, upon receipt of a packet from the routing object device of the relay server itself, converts a destination of the packet from the virtual address into an actual address and forwards the packet to the routing session.

Abstract: A disclosed relay apparatus includes: a generator that generates, upon receipt of a first packet that includes a first identifier of a virtual machine that is newly executed in an information processing apparatus connected to the relay apparatus from the information processing apparatus, a second packet that includes a second identifier of the virtual machine, which is different from the first identifier, and requests to set relay for the virtual machine; and a processing unit that sets the relay for the virtual machine by using the second identifier of the virtual machine, which is included in the second packet generated by the generator or received from the information processing apparatus.

Abstract: Techniques herein include systems and methods that extend functionality of transport networks including Transparent Interconnect of Lots of Links (TRILL) networks. Techniques include using a portion of information within transport device address encapsulation headers for purposes other than identifying source and destination device addresses. The system masks a portion of bits in an address header for an address lookup in forwarding tables of a transport network node. The remaining bits in the address field(s) become free bits that can be used for a variety of application purposes, such as flow identifier selection. By using information fields that already exist in encapsulation headers, such techniques provide additional information without increasing packet size or requiring new protocols. Embodiments can combine Equal-cost multi-path routing (ECMP) functionality, Reverse Path Forwarding (RPF) checks, and Time to live (TTL) protection at the same time.

Abstract: A method to manage data congestion in a computer network may include network devices to route data packets throughout the network. The method may also include a source node that sends data packets to any of the network devices. The method may further include a routing table at each network device that is updated by the source node, and the route the data packets are sent by any network device is based upon each respective routing table.

Abstract: The present invention discloses a method and device for a link protection in a virtual private local area network, which relates to the network data communication technology. The method of the present invention includes: in a networking process of a VPLS network, a link protection device establishing a main tunnel and a standby tunnel of MPLS TE for a link, and creating a VPLS forwarding table to deal with the information of the established MPLS TE main tunnel and standby tunnel; and when receiving a VPLS message, the link protection device searching the information of the MPLS TE main tunnel of the VPLS message according to a way of accessing the VPLS network of the VPLS message and the VPLS forwarding table, and if the found MPLS TE main tunnel is invalid, then transmitting the received VPLS message by adopting the standby tunnel of the MPLS TE main tunnel.

Abstract: A system is provided comprising a computer system and a dynamic network interfaces application that executes on the computer system. The dynamic network interfaces application activates a virtual local area network (VLAN) by associating subnet interface information and a virtual local area network tag, wherein the virtual local area network tag is unrelated to and randomly combined with the subnet interface information, and by transmitting the association of the subnet interface information and the virtual local area network tag to a firewall component and to a network access component.

Abstract: Described aspects provide for improving the mobility of wireless communication devices between one network domain and another network domain, specifically, but not limited to, between a Wireless Local Area Network (WLAN) and a cellular network and the like. Present aspects provide for services to be moved seamlessly and in a reliable manner between the cellular and WLAN domains in order to minimize service disruption for the end user and provide the requisite Quality of Service (QoS) for the different applications. The aspects herein presented provide for various mechanisms that serve to improve the decision points related to when and what technology each service is expected to be associated with and provides better techniques to move the wireless communication device between cellular and WLAN domains when in-traffic and when idle.

Abstract: Some embodiments provide a controller for managing several managed switching elements that forward data in a network. The controller includes an interface for receiving input logical control plane data. It also includes a converter for converting the input logical control plane data to output logical forwarding plane data. The logical forwarding plane data for subsequent translation into a set of physical forwarding behaviors that direct the forwarding of data by the managed switching elements.

Abstract: In one embodiment, a method includes establishing in a Virtual Private Local Area Network (LAN) Service (VPLS) over Multi-Protocol Label Switching (MPLS) network a floating pseudowire between a first provider edge router and a redundancy group having a plurality of provider edge routers each configured to forward data toward a external device. Each provider edge router in the redundancy group is configured to maintain an active link to the external device. A provider edge router that is not a member of the redundancy group sends data directed to the external device through the floating pseudowire. Only one provider edge router in the redundancy group receives and forwards the particular data to the external device.

Abstract: An Ethernet network comprises nodes which support a plurality of different forwarding modes. A range of VLAN Identifiers (VIDs) are allocated to each of the forwarding modes. Connections are configured between a source node and a destination node of the network using different forwarding modes. Packets carrying data traffic are sent to the destination node by selectively setting a VID in a packet to a first value, to transfer a packet via a first connection and a first forwarding mode, and a second value to transfer a packet via the second connection and the second forwarding mode. Packets received from both of the connections and sent on to an end user. VLAN Identifiers can be allocated to different releases of functionality at nodes (e.g. software releases) such that packets are forwarded via a set of nodes supporting a first release, or via a set of nodes supporting a second release.

Abstract: An information handling system is provided. The information handling system includes systems and methods for providing link bandwidth conservation between a local area network and a TRILL campus network. Such an information handling system includes a plurality of processing modules provided by a computer processor where the plurality of processing modules including a selective packet filter and a control plane unit and memory in communication with the plurality of processing modules. The memory stores a VLAN port bitmap and a snooping table. The information handling system also has a plurality of ports, which includes at least one Ethernet port for connecting the information handling device to a LAN and a plurality of bridging ports for connecting the information handling device to a plurality of routing bridges.

Abstract: An apparatus comprising an edge virtual bridging (EVB) bridge, and an EVB station coupled to the EVB bridge, wherein the EVB station is configured to send to the EVB bridge a virtual station interface (VSI) discovery and configuration protocol (VDP) request comprising a filter information (info) field without specifying a virtual local area network (VLAN) identifier (ID), and wherein the EVB bridge is configured to send a VLAN ID (VID) to the EVB station in a second filter info field in a VDP response to the VDP request.

Abstract: A method and apparatus that operates two bridging protocols in a hybrid bridging node is described. The operation of the two bridging protocols in the hybrid node allows for an incremental transition of a provider bridging network from operating a legacy bridging protocol that shares MAC addresses to a bridging network that operates VPLS and/or PBB bridging protocols. The hybrid bridging node selectively broadcasts unicast packets with unknown MAC addresses from the nodes operating VPLS and/or PBB to nodes operating a legacy bridging protocol.

Abstract: Techniques are provided to start a virtual service node that is configured to provide network traffic services for one or more virtual machines. The virtual service node has at least one associated service profile comprising identifiers for corresponding service policies for network traffic services. The service policies identified in the at least one associated service profile are retrieved. A virtual machine is started with an associated virtual interface and a port profile is applied to the virtual interface, including information identifying the service profile. Information is provided to the virtual service node that informs the virtual service node of network parameters and assigned service profile of the virtual machine. Network traffic associated with the virtual machine is intercepted and redirected to the virtual service node. A virtual service data path is provided that enables dynamic service binding, virtual machine mobility support, and virtual service node chaining and/or clustering.

Abstract: Methods and apparatus for interfaces to manage direct network peerings. A system may include a data center, endpoint routers and a connectivity coordinator. The coordinator implements a programmatic interface defining connectivity operations. The coordinator receives a request for dedicated connectivity to data center resources, formatted according to the interface. The coordinator selects a target endpoint router at which to establish a physical link to implement the dedicated connectivity, and transmits a response identifying the target endpoint router and including configuration instructions for setting up a physical link for the dedicated connectivity.

Abstract: Methods and systems for selectively processing VLAN traffic from different networks while allowing flexible VLAN identifier assignment are disclosed. According to one aspect, a layer 2 switch includes a virtual switch identifier data structure that associates a VLAN identifier extracted from a layer 2 frame and a port identifier corresponding to a port on which a frame is received with a virtual switch identifier. The virtual switch identifier is used to select a per-virtual-switch data structure, such as a forwarding table. The per-virtual-switch data structure is used to control processing of the layer 2 frame on a per-virtual-switch basis. The per-virtual-switch data structure may also be updated separately from the data structures assigned to other virtual switches.

Abstract: Some embodiments provide a distributed control system for controlling managed switching elements of a network. The distributed control system comprises a first network virtualizer for converting a first set of input logical forwarding plane data to a first set of output physical control plane data. It also includes a second network virtualizer for converting a second set of input logical forwarding plane data to a second set of output physical control plane data. In some embodiments, the physical control plane data is translated into physical forwarding behaviors that direct the forwarding of data by the managed switching elements.

Abstract: An apparatus comprising an edge virtual bridging (EVB) bridge, and an EVB station coupled to the EVB bridge, wherein the EVB station is configured to send to the EVB bridge a virtual station interface (VSI) discovery and configuration protocol (VDP) request comprising a filter information (info) field without specifying a virtual local area network (VLAN) identifier (ID), and wherein the EVB bridge is configured to send a VLAN ID (VID) to the EVB station in a second filter info field in a VDP response to the VDP request.

Abstract: A network adapter has a first and second virtual local area network (“VLAN”) device configured on each of first and second physical ports of the network adapter. The second VLAN devices are configured as a logically bonded, virtual device.

Abstract: Virtual links may be used to divert traffic within an Ethernet network without affecting overall traffic patterns on the Ethernet network. In one embodiment, the virtual link may be established on the network via a routing system in use on the network. Nodes on a defined path for the virtual link will install forwarding state for the virtual link so that traffic may follow the defined path through the network. The logical view of the virtual link, from a routing perspective however, has the same cost as the shortest path between the endpoints of the virtual link and, accordingly, does not affect other traffic patterns on the network. Once established, the end nodes on the virtual path will have two equal cost paths through the network—one following the shortest path tree and one along the path for the virtual link. The end nodes may use a tie breaking process in an Equal Cost Multi Path (ECMP) selection process to preferentially select the virtual link over the shortest path.

Abstract: A system and method for transmitting packets over two different network protocols without protocol conversion in any switches. A computer system comprises host computers and target storage arrays, or targets, coupled to one another through a Enhanced Ethernet network. Each of the host computers and the targets is configured to transmit encapsulated packets, such as a Fiber Channel over Ethernet (FCoE) packet. During system configuration, each of the targets is set to be the only target included in a virtual local area network (VLAN) with a corresponding unique VLAN identifier (ID). A given host computer logins to multiple assigned targets using a predefined Fiber Channel protocol. In response to a login request, a corresponding target assigns and conveys a N_Port ID that comprises a VLAN ID and a unique Host ID to the host computer in a reply message. A virtual link is established between the host computer and the target storage array.

Abstract: In one embodiment, an apparatus includes an Ethernet port, for connection to an Ethernet access network providing multiple different services. A plurality of local service ports are provided for connection to items of peripheral customer premises equipment (CPE), each item supporting a different, respective service. A bridge is coupled to convey data frames between the Ethernet port and the local service ports. A controller is coupled to receive via the Ethernet port at least one provisioning message indicating associations between the services and respective Virtual Local Area Network (VLAN) identifiers, and to configure the bridge, responsively to the provisioning message, to forward the data frames received via the Ethernet port on each VLAN to a respective service port in accordance with the associations.

Abstract: Techniques are provided for establishment of multiple concurrent virtual networks. In one example, there is provided a method operable by a message management unit (MMU) or the like. The method may involve establishing communication handles with a plurality of virtual network interfaces (VNIs) operatively coupled to an operating system, and establishing a network communications socket (NCS) operatively connected to a plurality of virtual layered networks. The method may involve establishing data channels that couple the MMU and its components with the respective VNIs of the MMU, and allowing the virtual layered networks to be concurrently transported on top of physical network(s). The method may involve facilitating communication between the operating system and the virtual layered networks via the combination of the established data channels, the established handles and a network software stack of the operating system.

Abstract: An upgraded edge node (e.g., enhanced PBB edge node, enhanced IP/MPLS edge node) and a method are described herein for providing a VLAN service for a customer in a metro network. In addition, a metro network is described herein which includes the upgraded edge nodes, traditional PB edge nodes, and a PB domain that has PB core nodes located therein.

Abstract: Methods, systems, and computer program products for selective layer 2 port blocking using layer 2 source addresses are disclosed. According to one method, a layer 2 frame is received. An I/O port block list is identified based on a layer 2 source address in the layer 2 frame. A set of ports to which the layer 2 fame should be forwarded is identified. The frame is blocked from being forwarded to ports in the set that are also in the I/O port block list.

Abstract: An apparatus including a port to transmit first frames and receive second frames over a communication channel, the port including a collision detect circuit and a duplex mismatch circuit. The collision detect circuit detects collisions on the communication channel between the first frames and the second frames. The duplex mismatch circuit declares a duplex mismatch when the communication channel was established without attempting auto-negotiation, the port is in a half-duplex mode, and the collision detect circuit detects a very late collision involving one of the first frames. The very late collision occurs after a predetermined amount of data has been transmitted in the one of the first frames. The duplex mismatch indicates that a full-duplex mode is used with respect to the second frames.

Abstract: A plurality of partitions can be defined in a database for a multi-tenant computing system provided on one or more processors such that each partition of the plurality of partitions is associated with only one business tenant of a set of business tenants supported by the multi-tenant system. The database can stored shared content that is shared among and accessible to all tenants of the multi-tenant computing system while tenant content for each business tenant can be stored in the database in one partition of the plurality of partitions. The one partition can be assigned to an associated business tenant. At least a portion of the tenant content can be unique to and associated with the associated business tenant.

Abstract: Methods and apparatus to provision cloud computing network elements are disclosed. A disclosed example method includes receiving a selection of a cloud networking template from a client, wherein the cloud networking template includes a data center connector type and a wide area network connector type, configuring a virtual machine on a host server based on the cloud networking template, configuring a data center connector based on the data center connector type, configuring a wide area network connector based on the wide area network connector type, and coupling the wide area network connector to the data center connector and coupling the data center connector to the virtual machine within the host server to enable the client to access the virtual machine.

Abstract: A manner of selecting communication traffic paths through a LAN, WAN, or similar communication network. Traffic received at a source bridge is forwarded to a destination bridge along a communication path selected from a plurality of possible, preferably EHEC paths. The paths may be discovered by a breadth first search and stored in a path selection table in association with a sequential index number. The paths are selected, for example by assigning a path to a VLAN by determining V mod N, comparing the result to indices on a path selection table that associates an unique index with each of the plurality of communication paths, and selecting the path associated with an index equal to the result, wherein N is the number of paths in the plurality of paths and V is a group identifier. The selected paths may be stored in the path selection table in association with the respective VLAN, and any received traffic for that VLAN is forwarded along the selected path.

Abstract: Techniques for processing packets in a network device include using a configuration table to determine a key corresponding to a packet. The configuration table may be indexed based on contents of a field of the packet (e.g., e/port or e/VLAN) to find a corresponding entry indicating a key format. When a key extension indicator has a first pre-determined value, a key extension field is added to the key format, and when the key extension indicator has a second pre-determined value, the key extension indicator is excluded from the key format. The populated key format or key (including any key extension field, if so determined) is used to determine a processing action for the packet. Key extension indicators support compatibility with non-legacy devices that utilize extended fields in packets, and with legacy devices. Embodiments of methods and network devices that support standard and extended keys are disclosed.

Abstract: In a network device such as a network switch having a port coupled to a communications medium dedicated to a single virtual local area network and another port coupled to a communications medium shared among multiple virtual local area networks for transmitting data frames between the dedicated communications medium and the shared communications medium, a method of identifying the virtual network associated with each data frame received by the network switch when transmitting the data frames over the shared communications medium. The method comprises receiving data frames from the dedicated communications medium coupled to one port, and, with respect to each data frame so received, inserting a new type field and a virtual network identifier field. The contents of the new type field indicate the data frame comprises a virtual network identifier field.

Abstract: In a network device such as a network switch having a port coupled to a communications medium dedicated to a single virtual local area network and another port coupled to a communications medium shared among multiple virtual local area networks for transmitting data frames between the dedicated communications medium and the shared communications medium, a method of identifying the virtual network associated with each data frame received by the network switch when transmitting the data frames over the shared communications medium. The method comprises receiving data frames from the dedicated communications medium coupled to one port, and, with respect to each data frame so received, inserting a new type field and a virtual network identifier field. The contents of the new type field indicate the data frame comprises a virtual network identifier field.