SRv6 uSID Lab

Segment Routing over IPv6 or SRv6 is the successor to SR-MPLS. SRv6 natively utilizes the IPv6 data plane to deliver Segment Routing capabilities, significantly simplifying network deployments. While SR-MPLS was a groundbreaking technology offering features like fast reroute, delay-based routing, and distributed and centralized traffic engineering, it remains an overlay technology with MPLS labels.

In contrast, SRv6 employs source routing by encoding the path in the packet header. It utilizes the IPv6 Routing Extension Header to carry multiple IPv6 addresses, which can, in our case, contain multiple SRv6 SIDs. The SRv6 uSID takes this concept further by allowing a single 128-bit IPv6 destination address to carry up to six individual SIDs.

SRv6 is highly robust and offers greater control and flexibility than ever before. This lab provides a hands-on environment to introduce users to the fundamental concepts of SRv6 uSID with L3VPN and BGPv6 Peering.

• This lab will demonstrate how to configure SRv6 uSID on two Cisco IOS XRv9000 PE routers to establish an L3VPN over a BGPv6 peering. The transport routers will exclusively operate in IPv6 mode, with ISIS preconfigured. Notably, we won't differentiate between prefixes within a VRF and will transport all IPv4 CE packets over the same path. Additionally, we'll utilize the default IGP path for data transmission. In subsequent labs, we'll explore the application of Flex-Algo to establish different paths and implement prefix matching for enhanced control.
• In this lab, you'll gain hands-on experience in configuring SRv6 uSID on Cisco IOS XRv9000 routers, specifically with IS-IS. You'll create virtual routing functions (VRFs) for IPv4 peering with the CE routers. Subsequently, you'll configure SRv6 to transport all VPNv4 traffic over an IPv6 backbone. 
• This document is composed of the following sections:
  • Introduction
  • Physical Topology
  • Lab Access Details
  • Validate IPV6/ISIS Config
  • SRv6 Configuration
  • MBGP L3VPN Configuration
  • PE-CE BGP Configuration
  • SRv6 L3VPN Verification
  • Conclusion

• Eight Cisco IOS XRv9000 v24.1.2 routers
• Two Cisco IOS-XE Routers running  15.5(2)S