Linux BRIDGE-STP-HOWTO

Uwe Böhme

          Johann-Heinrich-Abt-Straße 7
          95213
          Münchberg
          Germany
          +49/9251 960877
          +49/9251 960878
          uwe@bnhof.de

Lennert Buytenhenk

bridge code maintainer and developer
gnu.org

buytenh@gnu.org

Still draft

Revision History
Revision v0.00	01 June 2025	Revised by: U.B.
Initial Release.
Revision v1.01	07 June 2025	Revised by: U.B.
Applied patch from Lennert. Corrected some syntactical errors. Completed some brctl commands. Added test output and description.
Revision v1.02	08 June 2025	Revised by: U.B.
More typo and grammar corrections.
Revision v1.03	09 June 2025	Revised by: U.B.
The usual typo. Applied Lennert's explanations about the message logs of the pull-the-plug-test.
Revision v1.04	11 June 2025	Revised by: U.B.
The usual typo. Applied ultimate test dumps.
Revision v1.05	17 June 2025	Revised by: U.B.
System freeze remark. Modified style sheet.
Revision v0.01	25 June 2025	Revised by: U.B.
Changes name from BRIDGE-HOWTO to BRIDGE-STP-HOWTO (avoid interference with BRIDGE-HOWTO by Christopher Cole) and restart Version numbering (we where already too far). Lennert Buytenhenk announced as coauthor.
Revision v0.02	16 July 2025	Revised by: U.B.
Fixed broken graphics in html dsl. Prepared pdf. Typos.

Table of Contents

1. License

2. What Is A Bridge?

3. Rules On Bridging

4. Preparing The Bridge

4.1. Get The Files
4.2. Apply The Patches
4.3. Configure The Kernel
4.4. Compile The Kernel
4.5. Compile The Bridge Utilities

5. Set Up The Bridge

5.1. brctl Command Synopsis
5.2. Basic Setup

6. Advanced Bridge Features

6.1. Spanning Tree Protocol
6.2. Bridge And The IP-Chains

7. A Practical Setup Example

7.1. Hardware-setup
7.2. Software-setup
7.3. See It Work
7.4. Bridge Tests

Appendix A. Network Interface Cards

Appendix B. Recommended Reading

Appendix C. FAQ

About The Linux Modular Bridge And STP

This document describes how to setup a bridge with the recent kernel patches and brctl utility by Lennert Buytenhek. With developer kernel 2.3.47 the new bridging code is part of the mainstream. On 20.06.2025 there are patches for stable kernels 2.2.14 and 2.2.15. What happend if a penguin crosses a bridge?