Segment Routing over IPv6 (srv6) Configuration Module

This configuration module configures SRv6 over IS-IS or BGP and can use the advertised SIDs for global and L3VPN connectivity services.

Supported SRv6 features:

• Micro SIDs in F3216 format

• IS-IS routing with SRv6 TLVs

• Advertising SRv6 SIDs with BGP

• SRv6 next hops for global IPv4/IPv6 BGP routes (Layer-3 services with SRv6)

• BGP IPv4/IPv6 L3VPN over SRv6

You can use IS-IS or EBGP to advertise SRv6 SIDs[1], and use SRv6 for layer-3 services (IPv4 islands over SRv6, BGP-free core with IPv6) and IPv4/IPv6 layer-3 VPNs.

Platform Support

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

Device	SRv6 with IS-IS	SRv6 with EBGP	Global BGP over SRv6[2]	L3VPN over SRv6[3]
Arrcus ArcOS	✅	❌	❌	❌
Cisco Catalyst 8000v	✅	❌	❌	✅
Cisco IOL	✅	❌	❌	✅
Cisco IOL layer-2 image	✅	❌	❌	✅
Cisco IOS XRv/XRd	✅	✅	✅	✅
FRRouting	✅	✅	✅	✅
Nokia SR Linux	✅	❌	✅❗	❌
vJunos Router	✅	❌	✅	✅
vJunos Switch	✅	❌	✅	✅

Note

• The minimum Cisco IOS/XE release with working SRv6 is release 17.16.01a.

• Cisco 8000v does not support the shift-only microsegment behavior needed to interoperate with other SRv6 implementations.

• When in doubt, check the SRv6 integration test results.

Configurable Global and Node Parameters

• addressing.srv6_locator – global address pool[4] 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: False) to replace the IPv6 loopback address of each SRv6-enabled node with an IPv6 address allocated from the locator range

• srv6.bgp – enable BGP with IPv4 and IPv6 address families over SRv6 (disabled by default, more details).

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

• srv6.igp – list of IGP protocols for which to enable SRv6, default [isis]. To exchange SRv6 SIDs between autonomous systems, add ebgp to srv6.igp

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 Layer-3 Services and L3VPN Parameters

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

• srv6.bgp – Controls SRv6 next hops for global IPv4 and IPv6 BGP routes

• 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[5]

For tested examples, see the SRv6 integration tests.

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[1]

The module checks whether the corresponding routing module is enabled and will trigger a configuration error if it’s missing.

[2]

Using SRv6 next hops for global IPv4/IPv6 BGP routes.

[3]

Using SRv6 next hops for L3VPN routes. VPNv4 and VPNv6 address families are enabled on IPv6 IBGP sessions.

[4]

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

[5]

The only SRv6 service netlab supports over EBGP are global BGPv4 routes with SRv6 SID next hops.