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The Concept of vPC in Cisco Nexus Switching

 The Concept  of vPC in Cisco Nexus Switching


In the new Era, enterprise companies are more concentrating for the innovation of Datacenter environment. There are lot of things happened in Datacenter like now a days enterprise or service providers are thinking of Hyper-converged networks which can have the Software defined storage capacity with the use of X-86 based servers and on the top of it they are using various next generation technologies and applications. Companies are now investing more in the datacenter storage, computing, the new concept of East-west traffic is concerned now and the market share holder like Cisco using their technology called ACI to resolve it while other using the technologies SDN, NFV in their domains. so lot of things are improving for the Storage, switching, security and collaboration in Datacenter environment.

Audience # CCIE Datacenter, Cisco Students, Network Engineers, NOC/TAC Engineers, System Engineers and Network Experts

Apart from all the technologies what we discussed above, we start it one by one. We have lot of topics to covered like Datacenter Switching, Storage, UCS, Hyper-converged, Software defined or Server based compute network. But we can now start with the basic concepts of Datacenter and that starts from Datacenter switching. The first and the basic topic in Cisco Datacenter Switching is " The concept of vPC in Nexus Devices "
So if i am talking about the Nexus Devices, it means the Cisco devices used in the Datacenter environment with high capabilities and throughput.
vPC is the concept always used in the Nexus devices, it is similar to the concept of port channel in the basic network terms but having other capabilities. 

Port Channel and vPC
Port channel is the concept of aggregation of the two different ports links from one device to other. So port channel is between 2 devices always. Let me explain you in more clarity, we have two devices named " Device 1 and Device 2 " Both these devices have two links between them. So we can create a single port channel between Device 1 and Device 2 by using both the single links between them. When we are doing it we are actually increasing the full bandwidth between both the devices and other important thing is if one of the link is down the other link is there and the connection between the devices will not dropped but the throughput of the links decreased.

Fig 1.1- Port Channel

So Port-channel is well know to all of you now, but if i am talking about the concept of vPC, its little bit different. Here we have a device named " Device 1 and we have other two device as well named " Device 2 and Device 3" so you can have the vPC between the these 3 devices in form of port channel

Hain ? what it means ?
Well you actually doing the port channel between 3 devices a parent and 2 child devices in the network. It will increase the throughput or bandwidth of the links and also resolve the issues of the looping in the network. So vPC ( Virtual Port channel ) is a port channel between the devices more than 2 and used in the enterprise datacenter environment. 

Fig 1.2- vPC domain and Features


So you can have the following features using vPC
  • While STP blocks redundant links but by using vPC no block links.
  • Lowe oversubscription  and loop free network
Wow, then what is VSS ? i heard a lot on VSS ? 

VSS and vPC
VSS : Virtual Switching systems, generally used in the high end enterprises switches or you can use them in the Core network switching system. The concept is same as of vPC, the port channel between more than 2 devices with multi chassis environment but a slight difference is there.

Fig 1.3- VSS Concept


In VSS, the paired device have one control plane but two data plane, means if we have two devices in the VSS and having port channel with two other device down the line, the paired device ( Master and Slave ) , Master can be accessed and managed while Slave cannot be accessed as there is no control plane for Slave paired device. So they act as 1 device two the other devices with only one control plane, but if you are talking in respect to the vPC, the paired vPC devices have their own control plane and data plane Means ?

It means that if two devices are in vPC Paired, they have 2 control planes and 2 data planes while in VSS it is only 1 control plane and 2 data plane. in vPC you can manage and access both the vPC paired devices but in VSS you can't.

Hope you are clear about the port channel, VSS and vPC concept. We will come up with the more conceptions of all these technologies and the use cases in the live environment.