|TPMR(4)||Device Drivers Manual||TPMR(4)|
tpmrdriver implements an 802.1Q (originally 802.1aj) Two-Port MAC Relay (TPMR). A TPMR is a simplified Ethernet bridge that provides a subset of the functionality as found in bridge(4). A TPMR has exactly two ports, and unconditionally relays Ethernet packets between the two ports.
tpmr interfaces can be created at runtime
create command or by setting up a
hostname.if(5) configuration file
for netstart(8). The interface itself
can be configured with ifconfig(8); see
its manual page for more information.
tpmrcan 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
tpmrwith 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 trunkport fxp0 trunkport 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. TPMRs allow 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 ----+
# ifconfig etherip0 create # ifconfig tpmr0 create
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 trunkport em1 trunkport etherip0 up
An equivalent setup using MPLS pseudowires instead of IP as the transport can be built using mpw(4) interfaces.
tpmrdriver first appeared in OpenBSD 6.6.
|August 5, 2019||OpenBSD-current|