RFL SMX3 / 21
Page 4 of 22
Issue 1.4
User Manual
08 June 2009
3. Concatenation and Network Timing
SMX3/21 will operate on a network of concatenated X.21 links. A facility is provided
so that two co-located SMX3/21 (i.e. one at each end of separate X.21 links) units
can be linked ‘back to back’. This feature is referred to as Aggregate Concatenation.
In this case the units may be configured so that the data on Channel A and / or
Channel B is re-transmitted onto a second point to point link at the aggregate level
via the Concatenation Port. For this to operate all links must be synchronised to the
network master timing signal. If any link within the network is unsynchronised (e.g. a
single radio link), SMX3/21 provides the option to output master network clock
signals to otherwise unsynchronised links.
An alternative option is to concatenate a single data channel at V.24 level by daisy-
chaining the V.24 data links. This is referred to as Data Channel Concatenation. In
this case each X.21 link may be free-running (unsynchronised).
4. Equipment
Layout
