Principles – Grass Valley NV9000-SE v.5.0 User Manual
Page 78
60
Routers
Virtual Crosspoints
Formerly, physical re-entry was possible with cabling:
With re-entry, the output at port 1 in this illustration can be taken to any or all other outputs.
This is in itself insignificant because without any other factors, output 1 is simply a copy of one
of the inputs. Input 1 could have been taken to outputs 8, 9, 10, and 11.
One significant fact of re-entry is that, with initial setup, any input can now be routed to outpus
8, 9, 10, and 11 in a single take (to output 1). Further, a panel operator need not know about the
existence of output ports 8–11.
Another significant fact is that if the output undergoes any internal processing (such as break-
away or signal conditioning) it is not an identical copy of an input and the re-entry is required of
the output is to be distributed to other outputs.
Virtual crosspoints provide virtual re-entry and without cabling, without using any ports, and
without the frame delays inherent in physical re-entry.
Virtual re-entry allows:
•
Indirection, and in fact, multiple levels of indirection.
•
Routing to multiple outputs (in a single take).
Often, the multiple outputs include a monitor.
•
Controlling the device name that appears on the operators’ control panels.
•
Hiding implementation details from the operator(s).
Principles
1 Virtual crosspoints are implemented in tables in the NV9000 software in the system control-
ler (and not in the router). There is no direct cost associated with them.
(The virtual crosspoints are simulated crosspoints, but they appear to be real crosspoints to
the operator. The result of their use, of course, are real routes.)
2 Virtual crosspoints are assigned to individual physical levels in individual routers. (Your
switching requirements might require that you define virtual crosspoints on several levels,
perhaps in several routers.)
3 If you want a physical level to have virtual crosspoints, you must specify the number of vir-
tual crosspoints. There is no limit to the number of virtual crosspoints you can define for a
physical level. The number you actually require will generally be less than or equal to the
number of outputs in the physical level. (See
In 11
In 3
In 2
In 1
Out 1
Out 8
Out 9
Out 10
Out 11
• • •
• • •