Multipath Traffic Engineering for WAN & AIDC#

Zhaohui (Jeffrey) Zhang — HPE (with Kireeti Kompella)

• Why: Challenges a 25-year-old either/or — you could have ECMP load balancing or fine-grained TE with bandwidth control, not both. Kompella (co-author of the original MPLS TE RFCs) proposing a unified construct for both WAN and AI datacenters is a notable architectural signal, and the IETF drafts are live.
• What: MPTE programs an optimally weighted load-balancing DAG (MPTED) across the network: a single construct with per-junction split ratios replaces the many parallel LSPs that conventional TE needs to fill fat pipes (their example: 1600 Gbps R1→R12 needs four LSP constructs conventionally, one MPTED with 25/25/50/50 splits under MPTE). Link failure adjusts junction ratios without reshaping the DAG; multiple ingresses and multiple egresses (multi-egress load spreading, not multicast) are supported with far less state than per-path tunnels.
• How: Junction state = incoming bandwidth + previous-hops + next-hops with weighted load shares; signaling via RSVP-TE (prototype), with BGP/PCEP/programmable-API (gRPC, YANG-backed) prototypes underway. Contextualized against the existing toolkit (auto-bandwidth, container LSPs/TE++, cBPS AI/ML bandwidth prediction, tactical TE), and connected to the new IETF RTGWG conversation on ML network scheduling (draft-kompella-rtgwg-mlnwsched) — reserving and isolating network resources per inference/training task, since TE only makes sense in an ML cluster when it is split among multiple tenants/tasks.
• Where applicable: WAN/MAN/DCI and multi-tenant AI clusters; assumes MPLS or IP-tunnel data planes and a controller/computer to originate MPTEDs. IETF draft-stage — conceptual architecture now, not shipping broadly. HPE/Juniper-heritage perspective.