Copyright (c) 2019 David Gwynne <dlg@openbsd.org>
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.Dd $Mdocdate: August 24 2020 $ .Dt TPMR 4 .Os .Sh NAME .Nm tpmr .Nd IEEE 802.1Q Two-Port MAC Relay interface .Sh SYNOPSIS .Cd "pseudo-device tpmr" .Sh DESCRIPTION The .Nm driver implements an 802.1Q (originally 802.1aj) Two-Port MAC Relay (TPMR). A TPMR is a simplified Ethernet bridge with exactly two member ports, and it unconditionally relays Ethernet packets between those ports.
p .Nm interfaces can be created at runtime using the c ifconfig tpmr Ns Ar N Ic create command or by setting up a .Xr hostname.if 5 configuration file for .Xr netstart 8 .
p Other forms of Ethernet bridging are available using the .Xr bridge 4 Ethernet bridge driver and the .Xr veb 4 Virtual Ethernet Bridge device. Link aggregation of Ethernet interfaces can be achieved using the .Xr aggr 4 and .Xr trunk 4 drivers. .Sh IOCTLS The following .Xr ioctl 2 calls and their structures are commonly use by .Nm and .Xr bridge 4 :
p l -bullet -offset indent -compact t .Dv SIOCBRDGADD t .Dv SIOCBRDGDEL .El .Sh EXAMPLES .Nm can be used to cross-connect Ethernet devices that support different physical media. For example, a device that supports a 100baseTX half-duplex connection can be connected to a switch with 1000baseSX optical ports by using .Nm with a pair of physical network interfaces, each of which supports the required media types. If .Xr fxp 4 is used to connect to the 100baseTX device, and .Xr em 4 is used to connect to the 1000baseSX switch, the following configuration can be used: d -literal -offset indent # ifconfig tpmr0 create # ifconfig tpmr0 add fxp0 add em0 # ifconfig fxp0 up # ifconfig em0 up # ifconfig tpmr0 up .Ed
p Multiple TPMRs can be chained to transport Ethernet traffic for a pair of devices over another network. Given two physically separate Ethernet switches, TPMRs can be used as follows to provide a point-to-point Ethernet link between them. .Nm with the .Cm link0 flag set allows the use of the Link Aggregation Control Protocol (LACP) or Spanning Tree Protocol (STP) by the switches to detect communication failures or connectivity loops respectively, which is not possible using .Xr bridge 4 as it filters those protocols.
p If Host A connected to Router B has the external IP address 192.0.2.10 on em0, Host D connected to Router C has the external IP address 198.51.100.14 on em0, and both hosts have em1 connected to the switches, the following configuration can be used to connect the switches together. .Xr etherip 4 is used to transport the Ethernet packets over the IP network. d -literal Switch X ---- Host A ---------- tunnel ----------- Host D ---- Switch E \e / \e / +---- Router B ---- Router C ----+ .Ed
p Create the .Nm and .Xr etherip 4 interfaces: d -literal -offset indent # ifconfig etherip0 create # ifconfig tpmr0 create link0 .Ed
p Configure the etherip interface: d -literal -offset indent (on Host A) # ifconfig etherip0 tunnel 192.0.2.10 198.51.100.14 up (on Host D) # ifconfig etherip0 tunnel 198.51.100.14 192.0.2.10 up .Ed
p Add the etherip interface and physical interface to the TPMR: d -literal -offset indent # ifconfig tpmr0 add em1 add etherip0 up .Ed
p
An equivalent setup using MPLS pseudowires instead of IP as the
transport can be built using
.Xr mpw 4
interfaces.
.Sh SEE ALSO
.Xr aggr 4 ,
.Xr bridge 4 ,
.Xr pf 4 ,
.Xr trunk 4 ,
.Xr veb 4 ,
.Xr hostname.if 5 ,
.Xr ifconfig 8 ,
.Xr netstart 8
.Sh STANDARDS
.Rs
.%T IEEE 802.1Q
.Re
.Rs
.%T IEEE 802.1aj
.Re
.Sh HISTORY
The
.Nm
driver first appeared in
.Ox 6.6 .