Cisco SDR and VDC Features

For the SkyLifter project I wish to implement some additional virtualization features. What are Cisco Virtualization options?

  • VRF Lite
  • SDR – Secure Domain Router
  • VDC – Virtual Device Context

VRF Lite

By default a router uses a single global routing table that contains all the directly connected networks and prefixes that it learned through static or dynamic routing protocols.

VRFs are like VLANs for routers, instead of using a single global routing table we can use multiple virtual routing tables. Each interface of the router is assigned to a different VRF.

VRFs are commonly used for MPLS deployments, when we use VRFs without MPLS then we call it VRF lite.

Secure Domain Router (SDR)

Cisco IOS XR Software includes support for an HVR technology known as Secure Domain Routers (SDRs).

The HVR technology dedicates both control plane and data plane resources on a per-module boundary to individual virtual entities, so there is no sharing of either control plane or data plane resources. It is sometimes said that the only resource HVRs share is sheet metal. A lightweight shim layer provides low-level communication between HVRs, who otherwise believe they are independent router entities. Because of dedicated control plane and data plane resources, software applications and forwarding hardware need not implement virtualization. This separation effectively eliminates arbitration for resources between virtual routing entities.

Secure domain routers (SDRs) provide a means of partitioning a router into multiple, independent routers. SDRs perform routing functions in the same manner as a physical router but share resources with the rest of the system. For example, the applications, configurations, protocols, and routing tables assigned to an SDR belong to that SDR only, but other functions such as chassis control, switch fabric, and partitioning are shared with the rest of the system.

SDRs provide full isolation between virtualized routing instances through the use of Distributed Route Processors (DRPs) for extra control plane resources. SDRs are defined on per-slot boundaries, with entire Route Processors (RPs) and Modular Services Cards (MSCs) dedicated to an SDR. Figure below depicts the deployment of SDRs on a Cisco CRS-1 Carrier Routing System running Cisco IOS XR Software.


Note: SDR is only available on IOS-XR devices 12K, ASR 9K, CRS. It isn’t usefull for my SkyLifter lab.

You can find more info about Cisco SDR on Cisco White Paper Router Virtualization in Service Providers

Virtual Device Context

Cisco NX-OS introduces support for virtual device contexts (VDCs), which allows the switches to be virtualized at the device level. Each configured VDC presents itself as a unique device to connected users within the framework of that physical switch. The VDC runs as a separate logical entity within the switch, maintaining its own unique set of running software processes, having its own configuration, and being managed by a separate administrator.

Note: This feature looks like Juniper Logical System feature but it is not supported by IOS XRv. It isn’t usefull for my SkyLifter lab.

You can find more info about VDC on Cisco White Paper Technical Overview of Virtual Device Contexts

6 thoughts on “Cisco SDR and VDC Features

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