User guide

TD 92422GB
18 February 2010 / Ver. E
System Planning
Ascom IP-DECT System
18
The fibre modem is used for conversion between fibre optic/copper cables. The following
conditions must be met:
• Jitter and wander must be less than ± 50 ns
• Delay over media (incl. cabling) must be less than 50 µs
• Transparent mode
Example: Westermo ODW-631 SM-LC15, ODW-631 MM-LC2
Each synchronization port sends and receives (both directions) synchronization signals.
Each IPBL has two ports (in/out) for ring synchronization and two ports (in/out) for
reference synchronization.
The ring synchronization can be made in two different ways:
• Redundant (preferred)
• Non redundant
Each synchronization ring dynamically assigns a sync master.
Redundant ring synchronization
Redundancy is achieved when the IPBLs are connected in a ring. If one IPBL is not working
properly (single point of failure) all other IPBLs will be kept in synchronization due to the
synchronization ring. If more than one IPBL fail, one or more IPBL might get isolated from
the rest of the system.
Example with three IPBLs:
IPBL1 "Ring out" connected to IPBL2 "Ring in"
IPBL2 "Ring out" connected to IPBL3 "Ring in"
IPBL3 "Ring out" connected to IPBL1 "Ring in"
Figure 6. Redundant synchronization
Non redundant ring synchronization
Redundancy is not achieved when the IPBLs are connected in series.
Example with 3 IPBLs:
IPBL1 "Ring out" connected to IPBL2 "Ring in"
IPBL2 "Ring out" connected to IPBL3 "Ring in"
IPBL1 Ring out
IPBL2 Ring in
IPBL2 Ring out
IPBL3 Ring in
009
IPBL3 Ring out
IPBL1 Ring in