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(module-srv6)=

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 ✅ ❌ ✅ ✅

(srv6-l3vpn-supported-platforms)=

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 pool1 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]

(srv6-node-parameters)=

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.

Footnotes

  1. You can change the name of the default SRv6 locator pool with the topology.defaults.const.srv6.locator_pool.name parameter ↩