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GRE is probably the simpler of the Layer 3 methods and it can work over any IP core. When the virtual routers are connected over multiple hops through an IP cloud, you can use either Generic routing encapsulation ( GRE ) or Multiprotocol Label Switching ( MPLS ) virtual private networks. It’s possible to run into scalability issues when the number of devices grow and this type of design is typically used when you want to connect VRF back to back i.e no more than two devices. This is known as hop-by-hop virtualization. If they are physically ( directly ) connected to each other, you could use a technology known as VRF-lite to separate traffic and use 802.1Q to label the data plane.
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The virtualization of the interconnecting links depends on how the virtual routers are connected to each other. VLANs 201 and 101 remain separate entities. Both of these VLANs can share one physical wire to provide L2 reachability between hosts connected to Switch B and Switch A via Switch C. The diagram below displays two independent VLANs, VLAN201, and VLAN101. These VLAN trunks were created to transport multiple VLANs over a single Ethernet interface. To extend the path across multiple switches at Layer 2, VLAN tagging (802.1Q) can be used to carry VLAN information between switches. VLANs have been traditionally used and hosts from one user group are mapped to a single VLAN. Each virtual network could correspond to a user group or a specific security function.Įnd-to-end path isolation requires the virtualization of networking devices and their interconnecting links. With one-to-many network virtualization, a single physical network is logically segmented into multiple virtual networks. By definition they seem to be opposites but in the world of network virtualization they fall under the same umbrella. “One to many” means you segment one physical network into multiple logical segments on the other hand, “many to one” includes consolidating multiple physical devices into one logical entity. Network Virtualization can be grouped by two methods: