Segment Routing over IPv6 (srv6) Configuration Module

This configuration module configures SRv6 over IS-IS with IBGP to advertise SID reachability

Supported SRv6 features:

  • End SIDs (nodes) and End-x SIDs (links), all statically allocated

  • IS-IS routing protocol with SRv6 TLVs

  • BGP L3VPN v4/v6 over SRv6

The module currently depends on IS-IS and will trigger a configuration error if the isis module is not enabled in the network topology. It is initially focused on the L3VPN use case; IPv4 islands over SRv6 or IPv6 transport between SRv6 endpoints will be added once FRRouting supports them.

Platform Support

The following table describes the per-platform support of individual router-level SRv6 features:

Operating system

IS-IS

OSPFv3

BGP v4/v6

Transit only

FRR

✅

❌

❌

❌

Nokia SR OS

✅

❌

✅

✅

BGP/SRv6 L3VPN

Operating system

VPNv4

VPNv6

FRR

✅

✅ ❗️

Nokia SR OS

❌

❌

Notes

  • VPNv4 and VPNv6 address families are enabled on IPv6 IBGP sessions

Configurable Global and Node Parameters

  • addressing.srv6_locator – global address pool[1] for allocation of SRv6 locator prefixes, the default prefix is defined in topology.defaults.srv6.locator_pool (5F00::/16, the IANA reserved range defined by RFC9602

  • srv6.allocate_loopback – global flag (default: True) to replace the IPv6 loopback address of each SRv6-enabled node with an IP allocated from the locator range

  • srv6.bgp – enable BGP with IPv4 and IPv6 address families over SRv6, default IPv4 + IPv6 over iBGP.

  • srv6.vpn – enable BGP with VPNv4 and VPNv6 address families over SRv6. BGP/SRv6 L3VPN is disabled by default.

  • srv6.igp – list of IGP protocols for which to enable SRv6, default [isis]

Node Parameters

  • srv6.locator: an optional IPv6 address prefix to allocate to a given SRv6 node; by default, each node is assigned a unique /48 prefix from the global pool

  • srv6.transit_only: an optional Boolean flag to optimize resource usage and only allocate transit behaviors, not endpoint behaviors

Configurable BGP/SRv6 IPv4/6 and L3VPN Parameters

This module provides 2 parameters that are identical in structure, controlling different BGP address families:

  • srv6.bgp – Controls IPv4 and IPv6 address families

  • srv6.vpn – Controls VPNv4 and VPNv6 address families

Each parameter could be a boolean (True to enable both IP address families on IBGP sessions), or a dictionary of parameters:

  • ipv4 – enable IPv4/VPNv4 address family

  • ipv6 – enable IPv6/VPNv6 address family

ipv4 and ipv6 parameters could be:

  • Boolean value False to disable the address family within node data (overwriting global defaults)

  • Boolean value True to enable the address family on IBGP sessions

  • A string or a list of ibgp/ebgp keywords

For a tested example, see the IPv4 L3VPN over SRv6 topology.