RFC 2676 QoS Routing Mechanisms and OSPF Extensions August 1999 Table of Contents 1. Introduction 3 1.1. Overall Framework . . . . . . . . . . . . . . . . . . . . 3 1.2. Simplifying Assumptions . . . . . . . . . . . . . . . . . 5 2. Path Selection Information and Algorithms 7 2.1. Metrics . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.2. Advertisement of Link State Information . . . . . . . . . 8 2.3. Path Selection . . . . . . . . . . . . . . . . . . . . .10 2.3.1. Path Computation Algorithm . . . . . . . . . . .11 3. OSPF Protocol Extensions 16 3.1. QoS -- Optional Capabilities . . . . . . . . . . . . . .17 3.2. Encoding Resources as Extended TOS . . . . . . . . . . .17 3.2.1. Encoding bandwidth resource . . . . . . . . . . .19 3.2.2. Encoding Delay . . . . . . . . . . . . . . . . .21 3.3. Packet Formats . . . . . . . . . . . . . . . . . . . . .21 3.4. Calculating the Inter-area Routes . . . . . . . . . . . .22 3.5. Open Issues . . . . . . . . . . . . . . . . . . . . . . .22 4. A Reference Implementation based on GateD 22 4.1. The Gate Daemon (GateD) Program . . . . . . . . . . . . .22 4.2. Implementing the QoS Extensions of OSPF . . . . . . . . .23 4.2.1. Design Objectives and Scope . . . . . . . . . . .23 4.2.2. Architecture . . . . . . . . . . . . . . . . . .24 4.3. Major Implementation Issues . . . . . . . . . . . . . . .25 4.4. Bandwidth and Processing Overhead of QoS Routing . . . .29 5. Security Considerations 32 A. Pseudocode for the BF Based Pre-Computation Algorithm 33 B. On-Demand Dijkstra Algorithm for QoS Path Computation 36 C. Precomputation Using Dijkstra Algorithm 39 D. Explicit Routing Support 43 Endnotes 45 References 46 Authors' Addresses 48 Full Copyright Statement 50 Apostolopoulos, et al. Experimental