MPW(4) Device Drivers Manual MPW(4)

mpwMPLS Ethernet pseudowire

pseudo-device mpw

The mpw interface is used to create an MPLS Ethernet layer 2 tunnel between two points.

An mpw interface can be created at runtime using the mpwN create command or by setting up a hostname.if(5) configuration file for netstart(8). The interface itself can be configured with ifconfig(8).

The local MPLS label, the remote MPLS label and neighbor, use of pseudowire control words, or flow-aware transport are normally configured after negotiation with a remote system using ldpd(8), but it is also possible to configure them manually using ifconfig(8).

Create a pseudowire with local label 20 and remote label 21 on neighbor

# ifconfig mpw5 create
# ifconfig mpw5 mplslabel 20 pweneighbor 21
# ifconfig mpw5 up

Enable the use of the Pseudowire Emulation Edge-to-Edge (PWE3) Control Word, and disable the use of a Flow label for Flow-Aware Transport of Pseudowires:

# ifconfig mpw5 pwecw -pwefat

mpw interfaces may be used to build a Virtual Private LAN Service (VPLS) with bridge(4). A VPLS is constructed with a full mesh of MPLS pseudowire tunnels between all peers, but this introduces loops in the topology. To prevent broadcast packets received from the VPLS being forwarded to its peers, all the pseudowire interfaces can be configured to enforce the split-horizon forwarding rule by adding them to the same protected bridge domain. Different VPLS meshes can be joined together on the same bridge using different identifiers for their protected domains:

# ifconfig mpw10 create up
# ifconfig mpw11 create up
# ifconfig mpw12 create up
# ifconfig bridge0 create
# ifconfig bridge0 add em2
# ifconfig bridge0 add mpw10 add mpw11 add mpw12
# ifconfig bridge0 protected mpw10 1
# ifconfig bridge0 protected mpw11 1
# ifconfig bridge0 protected mpw12 1

mpe(4), mpip(4), hostname.if(5), ifconfig(8), ldpd(8), netstart(8)

S. Bryant and P. Pate, Pseudo Wire Emulation Edge-to-Edge (PWE3) Architecture, RFC 3985, March 2005.

S. Bryant, G. Swallow, and L. Martini, Pseudowire Emulation Edge-to-Edge (PWE3) Control Word for Use over an MPLS PSN, RFC 4385, February 2005.

S. Bryant, C. Filsfils, U. Drafz, V. Kompella, J. Regan, and S. Amante, Flow-Aware Transport of Pseudowires over an MPLS Packet Switched Network, RFC 6391, November 2011.

The mpw kernel interface first appeared in OpenBSD 5.8.

The mpw driver was written by Rafael Zalamena <>.

March 18, 2021 OpenBSD 7.5