Network Slicing Overview

Network slicing enables network operators to define logical networks on a physical network. The logical networks are called network slices. The slices have a shared control plane and can have a dedicated data plane. You can define shared logical slices as an additional administrative constraint to steer LSPs.

A slice comprises a set of nodes, links, and prefixes of a transport network; see Figure 1 . Each slice is managed by a single network operator.

Figure 1: Example of Slices in a Network

You can configure network slices by using the GUI or REST APIs. The nodes and the links belonging to a slice are grouped into a topology group, and the slice (topology group) is identified by a group ID (also referred to as slice ID). A node and a link can be part of more than one slice (upto thousand slices). For information about configuring and working with a slice, see Group Nodes and Links into a Topology Group.

Label-switched paths (LSPs) are routed through nodes and links that have the same slice IDs. To constrain an LSP to traverse through a particular slice, you must assign the slice ID of that slice to the LSP. LSPs that do not have an assigned slice ID can be routed through any node or link, irrespective of whether a node or link is part of a slice. When a node or link in a slice is down, the LSPs are rerouted through a redundant path in the same slice as shown in Figure 2 and Figure 3.

In Figure 2, nodes vmx101 and vmx103 are connected through the slice with slice ID 827. The slice includes nodes vmx101, vmx102, vmx104, vmx105, vmx106, ios-xr8, and ios-xr9, and the links between these nodes. The traffic flows between vmx101 to vmx103 through a path comprising nodes vmx105, vmx102, vmx106, vmx104, and vmx107.

Figure 2: LSP Routed through a Slice

In Figure 3, the link between vmx102 and vmx106 is down, as indicated by the red F on the link. The traffic between vmx101 and vmx103 now flows through a redundant path within slice 827, which comprises nodes vmx105, vmx102, ios-xr8, ios-xr9, vmx014, and vmx107.