EVPN Flex Cross Connect - L2 P2P VPNs can be agile as well!#

Tobias Heister (Plusnet)

• Why: RFC 9744 (EVPN VPWS Flexible Cross-Connect, March 2025) is a fresh, immediately deployable answer to a real scaling problem: hundreds of per-port/per-VLAN pseudowires in aggregation networks collapsing into a handful of multiplexed service tunnels. Directly relevant to EVPN fabric and aggregation design.
• What: A practical explanation of how EVPN VPWS FXC (RFC 9744) reduces PW count in aggregation networks by ~95% (from 288 per region to 3 in Plusnet's example: 3 target categories, 12 AGGs per region, 24 ports per AGG). The mechanism: normalize VLANs across multiple physical interfaces and map them onto a single service tunnel, reducing both EVPN service labels and BGP signaling volume. Deployed in production at Plusnet; PoC-tested 2023/2024 on Juniper and Arista with interop working.
• How: Two modes: Default FXC (one route regardless of how many port/AC/VID combinations attach, no VID-to-instance cross-check) vs VLAN-Signaled FXC (one route per normalized VID per instance, enabling cross-checks). The critical step is VID normalization — the vendor/NOS must provide flexible L2 config options to translate port/VLAN combinations into normalized VIDs carried in the EVPN route. Arista Flex-Encap and "unmatched" features are called out as particularly well-suited.
• Where applicable: Service providers and operators with large L2 aggregation networks backhauling services toward BNGs or service routers. Requires vendor support for RFC 9744 (Juniper and Arista confirmed). The value depends heavily on the L2 normalization capabilities of your NOS.