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Video: Vectors 

05-23-2018 00:23

Service delivery through heterogeneous networks can be tricky, but the 128T makes it easy. It's common when multiple paths exist between routers, that these paths will have different characteristics such as quality and throughput. Characteristics adequate for one service may be insufficient for another service. Vectors are how you give each service its own unique....well, vector!...through the myriad of paths from one host to another.
Vectors are a software capability, introduced in our 3.1.7 release, that lets you prioritize how traffic gets sent over your network. Each interface on your 128T may have vector names -- text labels -- associated with it. When your 128T router is going through its route selection process to decide how to transmit traffic, it uses these vectors to influence one path over another. If you’re a "dyed-in-the-wool" router guy and are thinking to yourself “this sounds a lot like using cost to prefer a path” you’d be right -- but there’s one important difference: costs are fixed values assigned to interfaces, whereas vectors represent variable costs per interface, determined individually for per traffic type.
You see, each service that you’ve defined in your 128T network can assign values to these vectors uniquely. Assume you have two Internet connections with two different ISPs:

  • One’s a high speed broadband connection
  • The other is a high quality MPLS connection
In this mental model, let’s say we associate a vector named “broadband” with the former, and “mpls” with the latter.

Vectors and Services
Now think about the services that your network offers; perhaps you use:
  • a cloud-based videoconferencing application
  • surveillance cameras that send feeds back to your corporate datacenter
  • general purpose Internet traffic
For the videoconferencing application, you’ll set the priority (or cost) of the MPLS vector really low, since you want it to be the first choice for your video calls; you’ll also set the priority of the broadband vector to be higher, since you’d like it to be an eligible path if the MPLS link is down or congested.
For the surveillance cameras, perhaps you want the priority to be different: the priority of broadband vector is lowest, since you’d prefer it use the cheap path first. The MPLS vector is higher than broadband, so that if your broadband provider’s link isn’t up to snuff it will use MPLS as a backup path.
For Internet traffic, you might set the broadband vector’s priority low, and set the MPLS vector value to “never” be chosen -- in fact, in our configuration model you use the keyword “never”. This essentially sets the cost of that link to be infinite, guaranteeing that your basic Internet traffic will never use the MPLS interface under any circumstances -- even if the broadband link goes away.
So in this example you have three services on your network, and two paths for your traffic. Each of those services leverages the exact same topological infrastructure slightly differently, by substituting their own unique values for the “vector” variables ascribed to those interfaces.

Configuring Vectors
Configuring vectors is straightforward. Within each network-interface, you’ll configure vectors inside the neighborhood container. As mentioned earlier, vectors are really text labels.

NOTE: Neighborhoods are names in our modeling language that represent Layer 3 networks.

Next, you’ll create a service-policy and associate priority values for those vectors: broadband is priority 10, mpls is priority 20, things like that. Remember that these are treated like costs, so the lower the number, the more preferred the vector. 


Last, you’ll associate that service-policy with a service. My broadband = 10 and mpls = 20 policy would get assigned to my surveillance service, for example.
That’s all there is to it! If you’re interested in getting your hands dirty with vectors, I suggest you start by assigning one to each neighborhood right away. Until you reference them in a service-policy, they’re harmless. We recommend you name these vectors with representative names that reflect the type of connectivity -- like broadband, mpls, LTE, etc. But feel free to experiment.

#Vectors #services #ServicePolicies #configuration

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