Label switching features

Label switching features are a suite of networking technologies, most notably Segment Routing Multiprotocol Label Switching (SR-MPLS ), that forward traffic based on a short, pre-assigned label rather than performing a complex network-layer address lookup at every hop. This approach enables high-speed packet forwarding and supports advanced services such as Traffic Engineering, Quality of Service, and the creation of Virtual Private Networks (VPNs).

Starting with Cisco NX-OS Release 10.6(1s), you can configure these label switching features on the Cisco N9324C-SE1U, Cisco N9348Y2C6D-SE1U switches.

  • Segment Routing Layer 3 VPN feature with SR-MPLS underlay

Segment Routing Layer 3 VPN feature with SR-MPLS underlay

Segment Routing Layer 3 VPN with an SR-MPLS underlay is a network service that creates isolated routing domains for multiple tenants by using BGP to distribute VPN routes while leveraging a simplified and scalable Segment Routing-based MPLS core for packet transport, eliminating the need for traditional protocols like LDP.

For more information, see Configuring Segment Routing.

Label switching feature guidelines

This section outlines feature support, guidelines, and limitations for label switching functionalities on Cisco N9324C-SE1U, Cisco N9348Y2C6D-SE1U switches.

Table 1. Supported features and releases

Features

Release

Segment Routing Layer 3 VPN feature with SR-MPLS underlay

10.6(1s)

Supported Segment Routing Layer 3 VPN feature with SR-MPLS underlay features:

  • The chassis can be positioned as either a LEAF or a SPINE switch in the SR-MPLS fabric.

  • SR-MPLS underlay is supported with BGP-LU, OSPF, and ISIS underlay protocols.

  • L3VPN and L3 EVPN overlays over SR-MPLS underlay are supported using eBGP.

  • The implementation supports Node-SID, Prefix-SID, and Adj-SID.

  • SR-MPLS features are supported on L3 physical, L3 sub-interface, L3 Port-channel (PO), and L3 PO sub-interface types.

  • Hierarchical ECMP (Level-1 and Level-2) is supported for SR-MPLS paths.

  • Per-VRF VPN label encapsulation is supported.

  • MPLS Decap Statistics are supported for VPN label termination.

  • SVI (Switched Virtual Interface) is supported as an MPLS interface type.

Segment Routing Layer 3 VPN feature with SR-MPLS underlay limitations:

  • MPLS TTL propagation operates in Uniform Mode.

  • DSCP-EXP handling is Uniform during encapsulation and Pipe during decapsulation (tentative).

  • Default load-sharing for SR-MPLS traffic is based on Label and IP (up to 5-tuple).