MPLS for Linux

MPLS for Linux is an open-source project aimed at creating a set of MPLS signaling protocols along with an MPLS forwarding plane specifically for the Linux operating system. Pretty cool, right?

What's in the Mix?

So far, we've got an MPLS forwarding plane that works with the Linux 2.6.x kernel and a solid implementation of RFC3036 (that's LDP, by the way). This project actually has two main parts:

1. mpls-linux: The Forwarding Plane

• Supports Ethernet interfaces


• Works with PPP interfaces


• Includes a Virtual MPLS tunnel interface


• You can use global or interface-specific label spaces


• Label stacking is available too!


• Recursive label lookups? You bet!


• You can link any entry in the Linux routing table to an outgoing label (this covers multiple table support, TOS, and per-interface routing)


• This integrates nicely with the Linux QoS model


• DiffServ support is also here (E-LSPs and L-LSPs)


• Easier Ethernet over MPLS through ebtables


• Popping off labels on the penultimate hop - PHP (which helps avoid IPv4 lookup on egress LER)


• (Note: Support for ATM interfaces was removed)

2. ldp-portable: The Portable Implementation

• We've got unsolicited and on-demand modes implemented here!


• This supports both direct and indirect peers.


• The label distribution is controlled by policy.


• This works well with the Quagga routing platform (check out quagga-mpls below!)


• A flexible configuration API that mimics LDP-MIB makes it even easier to use.

A Bit of History Behind It All

The journey of MPLS for Linux began as a protocol analyzer for the LDP protocol. Initially, it used some cool encode and decode functions developed by Nortel Networks. This was back when it was first created during N+I Las Vegas '99 at their MPLS iLab.

By N+I Atlanta '99, it had matured into a makeshift implementation of LDP-03. During that event, it got rewritten according to procedures laid out in Appendix A of LDP-05. In April 2000, I joined Laurel Networks (www.laurelnetworks.com) where I continued developing LDP while making sure it stayed portable.

This led to splitting up the linux-mpls-ldp package into two parts: mpls-linux, which is all about the kernel-based forwarding plane released under GPL, and ldp-portable, a portable version of the LDP protocol released under LGPL.

The project made its way to Sourceforge on November 30, 2000. By January 2003, I started working at iNOC (www.internetnoc.com) where I was encouraged to keep working on this project and