# HN815: All About PCE

Page: https://stenobird.com/podcast/heavy-networking/hn815-all-about-pce
Text version: https://stenobird.com/podcast/heavy-networking/hn815-all-about-pce.md
Podcast: [Heavy Networking](https://stenobird.com/podcast/heavy-networking)
Published: 2026-02-20T18:11:47+00:00
Episode link: https://packetpushers.net/podcasts/heavy-networking/hn815-all-about-pce/
Audio file: https://feeds.packetpushers.net/link/12486/17280258/HN815.mp3
Processing state: processed
JSON: https://stenobird.com/v1/public/podcasts/heavy-networking/episodes/hn815-all-about-pce
Duration seconds: 4450

## Resource

Traditional routing protocols like OSPF are limited to the shortest path, often leading to congestion on primary links while alternate paths remain idle. Path Computation Element (PCE) solves this by providing a centralized, network-wide view to compute optimized paths based on real-time traffic and constraints.

## Highlights
- Main idea: PCE acts as an 'eye in the sky,' using a centralized controller to see the entire network topology and traffic load
- Practical takeaway: Deploying PCE in a 'read-only' mode provides immediate value through enhanced network visualization and topology mapping
- Main idea: Unlike standard Segment Routing (SR) which relies on IGP metrics, PCE-computed paths can optimize for specific constraints like delay or bandwidth
- Failure mode: Relying solely on distributed protocols like OSPF can lead to 'slammed' shortest paths even when underutilized alternate routes exist
- Practical takeaway: PCEP allows for real-time updates and notifications via TCP, making it suitable for managing wide-area networks (WAN) from centralized data centers

## Topics

Path Computation Element, PCEP, Traffic Engineering, Segment Routing, OSPF, Network Controller, BGP-LS, Network Topology

## Chapters
- 1:00 — The Limitations of Shortest-Path Routing: Why OSPF and standard IGPs fail to utilize available bandwidth on non-shortest paths and how PCE provides the necessary flexibility.
- 6:25 — PCE in the Data Center vs. Service Provider: An analysis of where Traffic Engineering (TE) applicability is strongest, focusing on large-scale service provider and enterprise environments.
- 11:50 — Architectural Models and PCE Clients: Understanding the hierarchy of PCE and the role of clients in requesting path computations and informing the controller of network state.
- 17:25 — PCEP and Network Visibility: How PCEP uses TCP connections to transport network information and the role of BGP-LS in distributing topology data.
- 34:30 — Distinguishing PCE from Segment Routing: Clarifying the relationship between Segment Routing (SR) and PCE, specifically regarding path computation criteria and SR-TE.
- 40:10 — Optimization Objectives and Constraints: Exploring the different parameters PCE can use for path computation, such as latency, bandwidth, and IGP metrics.
- 57:05 — Transitioning to Segment Routing: Discussing the coexistence of legacy protocols like LDP with modern Segment Routing and how PCE manages the transition.

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