RFC 2676 (rfc2676) - Page 2 of 50

QoS Routing Mechanisms and OSPF Extensions

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