An engineer has been asked to design a LAN topology with high Availability and the loop-free features of STP. It must also support EtherChannel between multiple chassis and a separate control plane for each switch terminating these multiple connections.
Which technology should the engineer recommend to be deployment on the upstream switches?
A . StackWise
B . FEX
C . VSS
D . VPC
Answer: D
Explanation:
Two Cisco Nexus 7000 switches can be combined into a vPC domain, allowing multichassis Link Aggregation Control Protocol (LACP) port-channel connections across the pair. vPCs (also known as virtual channel ports) can be built between the vPC switch pair and other neighboring devices. Even though the vPCs are terminated on two different physical switches, the vPC switch pair represents itself as a single switch to neighboring devices that are connected on the vPCs.
This allows the traditional triangles between the access and aggregation layers to be removed from the logical design. Physically, the access switches still connect to two different aggregation switches, but logically, the pair of Cisco Nexus 7000 switches acts as a single switch. The links between the access switch and aggregation switch pair are combined into a vPC, and STP treats the connection as a single link. As a result, STP does not block any of the links, and the complete bandwidth between the access and aggregation layers can be used. The concept of VPCs is similar to the Catalyst 6500 VSS (Virtual Switching System) technology. With vPCs, however, it is an “active/active” backplane model, whereas the Catalyst 6500 only has one supervisor active between VSS pair switches. This is discussed in more detail later. With VPC, the switches combine to provide FHRP services, and therefore both switches forward packets sent to a HSRP, VRRP, or GLBP virtual gateway MAC addresses, to avoid the routing polarization previously common to FHRPs.
The vPC technology allows loop-free designs to be created in the access and aggregation layers, increasing the total forwarding capacity and simplifying the network topology.
The vPC technology is a clustering technique that allows two Cisco Nexus 7000 switches to represent themselves as a single switch to other network devices. The vPC technology enables Layer 2 Multichassis EtherChannels (MEC) to be built between the other network device and the pair of Cisco Nexus switches.
Each peer device in the vPC domain runs its own control plane, and both devices work independently. Any potential control plane issues stay local to the peer device and does not propagate or impact the other peer device.
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