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Introduction
This article is meant to clarify the difference between the sync of the DECT protocol and the configuration/provisioning in an M-series DECT Multicell system (M400, M700 or M900)
The golden rule is to always remember that the DECT Primary in a system is not necessarily in charge of the configuration of the system or sharing the provisioning file with all other base stations
DECT Synchronisation
The DECT protocol is a time sensitive protocol and it's key all base stations are synched together to make sure the system can run smoothly and all handsets can connect, roam or handover in the coverage area
All base need to sync with each other then and they can do that two ways, over the air (via DECT wireless signal) or via LAN (the so called LAN Sync, based on protocol IEEE1588)
In both cases one base station will assume the role of Primary in the system: this base is only used to sync the DECT protocol over the whole system, it isn't in charge of synching the configuration or anything else
In a Snom DECT system by default the parameter called “Auto configure DECT sync source tree” on the WUI is enabled, which means the system will automatically choose its own primary base station
This primary may change from time to time, to reflect changes in the environment and to make sure the best base station is always the primary for DECT sync, based on the signal strength it can measure over all bases
If using LAN Sync, the system will initially choose a primary and an alternative primary in case the first one has issues, based on the network jitter and delay it can measure
It is important to check our LAN Sync requirements if you plan to use those, to make sure the local network is up to the task, and to make sure every base station can see at least another one with a minimum signal strength of -75dBm if using the sync over the air
Configuration Synchronisation
In order to work properly all the bases must have the same settings: once the multicell system is setup, settings are periodically synchronised across all the bases automatically via network
Settings exchanged between bases are “timestamped”, a base with a newer timestamp setting will push the settings to a base with an older timestamp setting
For this reason, you should make sure that always only one base is configured by the auto-provisioning server
By default Data synchronisation is done via a multicast protocol using the UDP port range of 49200 – 49999 and the the IP address in the range of 224.1.0.0 – 225.1.0.0
If multicast is not possible (not supported, filtered or are bases in different networks), it is possible to use the Peer-to-peer mode for Data sync, in this case a Data Sync Primary base must be defined
Peer-to-peer data sync uses unicast UDP and the same port range as the Multicast data sync
The DECT primary of the system is ONLY in charge of synchronising the DECT protocol around all base stations, not the configuration
If you are using Multicast, all base station will share it configuration over the network and the newest one will be used
If you are using Peer-to-peer only the Data Sync Primary will send the configuration to all other base stations
The DECT Primary and the Data Sync Primary can be the same base but that doesn't matter, they can also be different bases: the only important thing is that if you use peer-to-peer you need to provision the base which IP is set as Data Sync Primary
Conclusion
Always be aware if you are referring and working with DECT or configuration synchronisation, they are two completely different things on the DECT multicell system and they do not interfere between themselves
If the “Auto configure DECT sync source tree” parameter is enabled the system will automatically move the DECT primary if needed, but that will not affect the provisioning in any way, and if you are using multicast you can keep making changes on every base station and these will be propagated on the whole system (if you are not using provisioning, which would overwrite them)
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