[[octoi]]
== OCTOI TDMoIP mode

Instead of providing a programmatic client interface (<<client>>) enabling
external applications timeslot-granular access to the data of a E1 line,
`osmo-e1d` also supports an entirely separate mode of operation:
_TDMoIP using the OCTOI (Osmocom Community TDMoIP) protocol_.

In this mode of operation, osmo-e1d acts as interface between an E1 line
and a remote system over UDP/IP.  This allows you to transparently pass
an E1 line over an IP network such as the Internet.

`osmo-e1d` can operate either as client or as server for the OCTOI protocol.

=== osmo-e1d as OCTOI client

Below is an example configuration snippet for operating as an OCTOI client.

.Configuration snippet for operating as an OCTOI client
----
e1d
 interface 0 icE1usb
  usb-serial dc697407e7881531
  line 0
   mode e1oip <1>
octoi-client 192.168.7.2 10013 <2>
 local-bind 0.0.0.0 3333 <3>
 account foobar <4>
  mode ice1usb
  ice1usb serial-number dc697407e7881531 <5>
  ice1usb line-number 0
----
<1> we specify that Interface 0 Line 0 (I0:L0) of the icE1usb device with serial number dc697407e7881531 shall
    be used in `e1oip` mode.
<2> we instantiate an OCTOI client to the remote IP 192.168.7.2 / UDP port 10013
<3> we specify to bind locally to INADDR_ANY and local UDP port 3333
<4> we specify the account/user name to tell the server is `foobar`
<5> we specify that this OCTOI client instance shall use the icE1usb device with the given serial number. This
    must match the serial number used above when configuring the icE1usb line mode.

There can of course be any number of E1 interfaces/lines and clients; the example just shows one for clarity.

=== osmo-e1d as OCTOI server

Below is an example configuration snippet for operating as an OCTOI server.

.Configuration snippet for operating as an OCTOI server
----
e1d
 interface 0 icE1usb
  usb-serial dc697407e7881531
  line 0
   mode e1oip <1>
octoi-server
 local-bind 0.0.0.0 10013 <2>
 account foobar <3>
  mode ice1usb
  ice1usb serial-number dc697407e7881531 <4>
  ice1usb line-number 0
----
<1> we specify that Interface 0 Line 0 (I0:L0) of the icE1usb device with serial number dc697407e7881531 shall
    be used in `e1oip` mode.
<2> we bind the OCTOI server to UDP port 9999 of INADDR_ANY
<3> we specify a user account `foobar`
<4> we connect the user account `foobar` to the icE1usb serial number / line number specified above

There can of course be any number of E1 interfaces/lines and user accounts; the example just shows one for
clarity.