Colocated Hub » History » Revision 16

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laforge, 09/15/2022 07:44 PM

Colocated Hub

This page exists to collect planning about the future colocated OCTOI hub, see #5542

Block Diagrams

E1/TDM network

IP network

Rackmount units

Central Office server (2U / 67cm)

This is a 2U rack-mount server running all the relevant software.

See AVSt_Server for more details of the server


This is a 2U rack-mount server with the following connections:
  • Power
    • 2x AC power connections (redundant PSU)
  • Ethernet
    • 1x RJ45 100-Base-TX BMC
    • 2x RJ45 1000-Base-TX
  • E1
    • 8x E1 to a co-located Cisco AS5400 (see below)
    • 1x E1 to a co-located Livingston PM3 (see below)
    • 1x E1 to icE1usb/clock-source

icE1usb / E1 clock source (1U / 31cm)

This is a 1U rack mount system containing:
  • a PC-Engines APU3 embedded x86_64
  • an icE1usb with a custom RS422 interface board
  • a custom rs422 over voltage protection + 12V injection board

This icE1usb acts as a GPS-disciplined clock master. However, as no acutal RF GPS signal is available in the data centre, we are using an Ericsson GPS_02 attached via ~100m of RS-422.


  • Power
    • 2x AC power connections (1x APU, 1x RS422/GPS)
  • Ethernet
    • 1x RJ45 to internal VLAN
  • RS422
    • 1x RJ45 towards GPS02 on the roof

Cisco AS5400 RAS Server (2U / 49cm)


  • Power
    • 2x AC power connection (redundant PSU)
  • Ethernet
    • 1x RJ45 Ethernet (100-Base-TX) to internal VLAN
  • E1
    • 8x E1 (via break-out cable) to AVSt-Server
  • RS232
    • Serial console connection via USB-UART to AVSt_Server

Livingstion Portmaster 3 (2U / 31cm)


  • Power
    • 1x AC power connection
  • Ethernet
    • 1x RJ45 Ethernet (10-Base-TX) [yes, 10MBps] to internal VLAN
  • E1
    • 1x E1 to AVSt-Server
  • RS232
    • Serial console connection via USB-UART to AVSt_Server

Roof installation

On the roof of the data centre, the CAT5 cable with RS422 for the GPS03 arrives.

It will be passed through several DIN rail mounted OVP (Over Voltage Protection) circuits before connecting to the actual DIN-rail mounted Ericsson GPS03

The Ericsson GPS03 has a SMA connector, to which a SMA-male to N-Male coaxial cable is attached.

A Times Microwave LP-GTR-NFF lightning protector (N-female to N-femaile) is used to pass the coaxial cable through the enclosure

An external GPS antenna with N connector is plugged into the LP-GTR-NFF

Overview diagram

This diagram illustrates the parts and connections on the rooftop. Rectangular objects are DIN-rail mounted.


  • Like in the current hub at @laforge's basement, we should run the entire yate / osmo-e1d / dahdi-trunkdev inside a KVM with SRV-IO mapping the PCI devices


Public IP

Host IPv4 IPv6 IPv4-internal
avst ?
divf ?
as5400 ?
pm3 - -
icE1-apu - -
avst-bmc ? -

Misc / TODO

local verification with modem/ISDN-TA

It would be great if we could somehow verify local calls via the yate / hub excluding the complexity of the TDMoIP to compare calls without TDMoIP to calls with TDMoIP.

Unfortuantely I'm not aware of any really small PBX that would terminate the E1/S2M and offer S0/POTS ports. Adding antoher 3U for a PBX seems excessive.

Doing calls between PM3 and ASR5400 is of course an option, but ideally we'd have a real physical modem attached via a serial port, and a real HFC-S-USB for test purpose.

High-level parameters for data centre

  • 7U rackspace
  • 7x AC power outlet
  • 7x Ethernet switch port (one of which supports 10 MBps!)
    • some ports in a new VLAN
    • some ports in an existing VLAN of my other servers in Rack 1120
  • 1x CAT5 between rack and roof
  • about 10cm of space on DIN-rail on roof enclosure (to mount OVP + GPS03)


  • Required antenna cable length between rooftop enclosure and antenna
  • Mechanical antenna mounting details
  • detailed switch port / VLAN config

Updated by laforge 15 days ago · 16 revisions

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