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Video: Mr. PT's Neighborhood 

05-23-2018 00:23


In this installment of the 128T Data Model Series, we want to talk about the concept of neighborhoods in the 128T Networking Platform.

Neighborhoods
A Neighborhood is really just a name for a Layer 3 network that one or more of your 128T devices is attached to. But in this simple definition rests an incredibly subtle, but important concept in the 128T way of thinking; neighborhoods have three important influences on your network.

One: Automatic Connections Between 128Ts
First, as we were designing the software, we wanted each 128T router to be able to automatically identify and associate with other nearby 128T brethren. Of course, in the routing world, nearby devices are called neighbors. So what better name for a collection of nearby, neighboring routers than a neighborhood? That's really the crux of the first role of neighborhoods in your network: a neighborhood is used to describe the intention of connectivity between devices. 

All routers connect to more than one network. In the 128T data model, each network interface on your router can be assigned to a neighborhood. When two connected routers each have at least one interface in a common neighborhood, the conductor can construct and distribute configuration to those two routers - forming an introduction, essentially - causing them to peer with one another. This conductor function is governed by the topology type assigned to a router's neighborhood when you create it. 

Topology type can be one of three enumerated values:

  • mesh
  • hub
  • spoke (default)

​As you'd probably surmise, spokes connect to hubs, and everything connects to mesh. Hubs don't connect to other hubs and spokes don't connect to other spokes. In a typical branch office/data center deployment, you'd assign your branches to be spokes and your data center to be a hub. This will have the effect of having your branches connect to your data center, but not have your branches connect to one another. The real power of this topology type is evident when you add add another data center as a hub: all of the branches - whether it's one or one thousand - will automatically create a peering relationship with it when you commit your configuration. Add a new branch? Same thing...place it in the same neighborhood as its counterparts and it'll peer with the data centers with no fuss. 

So that's the first main function of these Layer 3 networks we call neighborhoods: automatically building topologies of the 128T routers that are attached to them.

Two: Multi-Tenant Network-Interfaces

The second function of neighborhoods operates in conjunction with tenants, and is used to define tenant membership. As we described in the Video: Tenancy in 128T, your 128T can identify a source of traffic in one of several ways:

  • assigning an interface to a tenant
  • associating a prefix to a tenant within a neighborhood
Because a neighborhood represents a Layer 3 network, any interface associated with that neighborhood on any 128T in your Authority will treat that network similarly. By defining a prefix within that neighborhood to represent a tenant, it doesn't matter which 128T interface those sessions arrive on from a device in that prefix, the tenancy is applied based on the neighborhood.

This is a powerful concept. How many of your edge routers have an interface that attaches to the Internet? By naming this your internet neighborhoodwhenever you define addresses or prefixes within this neighborhood to be associated as a tenant, all edge routers will immediately understand. When you add another edge router and assign its public-facing interface into the internet neighborhood, you don't need to go through any further configuration to let it know how to match inbound traffic to tenants: the rules are per-neighborhood, not per-device

Three: Vectors
The third and final function of neighborhoods is providing a way of asserting particular paths for different flavors of traffic by way of Vector Routing. This is a really cool concept, but rather than cover it here, we suggest you watch the Video: Vectors and read the How-To: Path Selection Using Vectors. 

#Neighborhoods #Vectors #Tenants #video
​​​​ #eLearning

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