SIU 02

The SIU (Site Integration Unit) is an optional element in the transport network of the Ericsson 2G RAN.

It includes functionalities like
  • 16 E1/T1 lines
  • 8 Gigabit Etghernet ports (up to 8x copper, up to 4x optical/SFP)
  • Ability to route IP/Ethernet traffic over E1
  • Ability to convert from Abis/E1 or PacketAbis/E1 to Ericsson PacketAbis/IP (L2TP)
  • Synchronization for E1
    • from SyncE
    • from IEEE PTP
    • from 1PPS input



The DC input voltage of nominal 24..48V can be applied in any polarity. It uses the same connector like e.g. the DUL 20 or DUG 20 units.


This is an RJ45 Ethernet port, internally connected to a BCM5221 Fast Ethernet PHY

It is configured to a fixed IP address of and provides telnet + SSH access.

The default user name is admin; the default password is hidden.

You will get access to a command line interface:

Connected to
Escape character is '^]'.

login: admin
STN CLI - ready


This is a 10P10C western connector, sometimes also called RJ50.

Internally, it connects to some protection circuitry and then to a series of three ST2485EC RS-422 transceivers.

The pinout is as follows

Pin Signal Function
1 RS422-C Non-Inverting input
2 RS422-C Inverting input
3 RS422-B Non-Inverting input ?!?
4 RS422-B Non-Inverting input 1PPS IN?
5 RS422-B Inverting input 1PPS IN?
6 ?
7 RS422-A Non-Inverting output 1PPS OUT
8 RS422-A Inverting output 1PPS OUT
10 +12V DC output Supply external GPS?

There is a OSHW design for a breakout-board with RS-422 transceivers so you get a CMOS level 1PPS input and output:


This is a block of 8 RJ45 connectors, each hosting two E1/T1 circuits.

Pin-out TBD.


This is a block of 8 RJ45 conncetors, each supporting one 10/100/1000 Mbps Ethernet port.

Four of the Ethernet connectors can alternatively be used with a SFP optical transceiver.

Further reading

Files (1)
20200719-siu-l2tp_2.pcap 20200719-siu-l2tp_2.pcap 38.5 KB L2TP pcap file showing establishment laforge, 07/19/2020 08:46 PM

Updated by laforge over 1 year ago · 8 revisions

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