User's Manual

Exalt Installation and Management Guide
EX-i Series (TDD) Digital Microwave Radios
206501-019 15
2016-05-24
When Sync is Lost
If the primary sync source (for example, the sync source radio or GPS source) signal is lost due to
equipment failure, a disconnected sync cable, or other conditions, the first radio in the daisy-chain
configuration set to AUTO SYNC resumes the sync function for the remaining connected radios.
If a radio is configured as SYNC RECIPIENT, transmission ceases if the sync signal does not appear
at the SYNC IN connector.
A radio running in AUTO SYNC (without the sync source) is said to be flywheeling. That is, the clock
is free-running off internal clocking and is no longer synchronized to any source.
If the original sync source is restored to the flywheeling radio configuration, the flywheeling radio
attempts to synchronize to this signal without causing transmission interruption. All interconnected
radios receiving sync from the flywheeling radio also continue to operate without interruption.
When the flywheeling radio runs independently for long periods of time, the synchronization signal
can be too far outside of the capture range of the synchronization loop, and portions of transmission
frames can be lost during the re-synchronization process. This condition is temporary and all
interconnected radios re-synchronize to the sync source, as necessary.
For GPS synchronization, the wiring inside the Exalt radio carries the GPS signal to the next radio
cabled in the system, even when power is removed from the SYNC SOURCE radio or during radio
failures. This provides redundancy for catastrophic failure of the SYNC SOURCE and maintains GPS
synchronization. If the GPS source is lost (for example, due to failure of the GPS unit, a disconnected
cable, or satellite blockage), the AUTO SYNC radio resumes synchronization duties for all collocated
radios.
LEDs
There are two LEDs on both the SYNC OUT and SYNC IN ports. Table 3 describes the two SYNC IN
and two SYNC OUT LEDs.
Virtual Local Area Network (VLAN)
VLAN segments information in a single connection and creates multiple separate connections to
secure information of one type or for one set of users from other information types or for other sets of
users. Exalt’s VLAN communications implementation adheres to the IEEE standard 802.1q.
In most cases, an Exalt radio acting as a Layer 2 bridge between two locations is only required to pass
traffic with VLAN tagging. Without additional configuration, all Exalt radios support frame sizes in
excess of 1900 bytes, which currently supports all defined VLAN packet sizes.
Some situations require Exalt radios to act upon VLAN traffic and perform any or all of the following
functions:
• Connect specific traffic, using VLAN tagging, to a specific port on the radio, such as management
traffic to the AUX port.
Note: Offset timing is not supported in all models at the time of this writing. Consult your
Exalt representative for details.
Note: If an application only requires the transparent passing of VLAN traffic, disable the
VLAN function.