ASR9k with Nv Clustering Part 1.

Part 1 will explan the general purpose of Nv part 2 will explain the configuration. ASR9k comes with a new feature as of 4.2.1 called Nv which stands for Network Virtualization. This allows two ASR9ks to appear as one logical router. This technology can be referred to as a cross stack ether-channel as it has the same general concept as others ie VPC,VSS,3750 etc. The biggest difference in Nv is that it seperates both the control-plane and the data-plane traffic. Where in other cases like VPC it was highly recommended not to send traffic through the peer-link and with VSS data and control plane mechanisms where on the same 10Gig Interfaces. There are some requirements to running Nv.

1.) Has to be RSP440 CPU need at least one per router
2.) Needs to be newer 10g line cards Either Thor or Trident Enhanced.
3.) EoB RSP links need to be 1g only the only SFP I was able to get working was a GLC-SX-MMD the RSPs are very sensitive.
4.) Needs 4.2.1 or above. At this time of writing 4.3.2 is the latest release and has some Nv fixes.

The cabling is simplistic. The general thought is we are bridging our RSP440s together for control-plane traffic and for data-plane traffic we are bridging 2 10gig line cards from each router for data plane traffic. Each RSP has 2 ports for management. Each RSP needs at least one connection from the RSP on the same subnet. Here is a cabling diagram.

ASRcabling

The thought is simple. Each RSP is connected to each other.

Now the interesting part about Nv is that a RSP is always primary and a RSP is always backup and they live on two different routers. For example. if RSP0 is the active RSP on rack0. The backup will be on Rack1.

The general idea of the data plane is simple. If a packet ends up on rack 0 destined that should be destined for rack 1 it will use the data-plane links between each 9k. A ASR9k can use either equal cost load balancing via Layer 3 or a device can use the same LACP port hashing we know and love. So it is possible to have a packet land on rack 0 destined for rack 1 and use the 10gig links for what they are designed for. Here is a example.

Flowbased

In this example a packet enters the ASR9k with Nv like it is one router. The packet destined for 10.0.0.0/24 lands on the router towards the left but needs to make it to the router to the right. So it is routed over the IRL/10gig link between 9ks.

In Part two I will go over the Nv configuration.

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