NAME
tpmr
—
IEEE 802.1Q Two-Port MAC Relay
interface
SYNOPSIS
pseudo-device tpmr
DESCRIPTION
The tpmr
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.
tpmr
interfaces can be created at runtime
using the ifconfig tpmr
N
create
command or by setting up a
hostname.if(5)
configuration file for netstart(8).
Other forms of Ethernet bridging are available using the bridge(4) Ethernet bridge driver and the veb(4) Virtual Ethernet Bridge device. Link aggregation of Ethernet interfaces can be achieved using the aggr(4) and trunk(4) drivers.
IOCTLS
The following ioctl(2) calls and their structures are commonly use by
tpmr
and bridge(4):
EXAMPLES
tpmr
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 tpmr
with a
pair of physical network interfaces, each of which supports the required
media types. If fxp(4) is used
to connect to the 100baseTX device, and em(4) is used to connect to the 1000baseSX switch, the
following configuration can be used:
# ifconfig tpmr0 create # ifconfig tpmr0 add fxp0 add em0 # ifconfig fxp0 up # ifconfig em0 up # ifconfig tpmr0 up
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. tpmr
with the
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 bridge(4) as it filters those protocols.
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. etherip(4) is used to transport the Ethernet packets over the IP network.
Switch X ---- Host A ---------- tunnel ----------- Host D ---- Switch E \ / \ / +---- Router B ---- Router C ----+
Create the tpmr
and
etherip(4) interfaces:
# ifconfig etherip0 create # ifconfig tpmr0 create link0
Configure the etherip interface:
(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
Add the etherip interface and physical interface to the TPMR:
# ifconfig tpmr0 add em1 add etherip0 up
An equivalent setup using MPLS pseudowires instead of IP as the transport can be built using mpw(4) interfaces.
SEE ALSO
aggr(4), bridge(4), pf(4), trunk(4), veb(4), hostname.if(5), ifconfig(8), netstart(8)
HISTORY
The tpmr
driver first appeared in
OpenBSD 6.6.