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Smart DeskStream Technical Presentation 42
Source Route Switching
‘Annex K’nComponents of Annex K ?
nConcentrator Relay Function (CRF)
lHandles switching process
lAll ports access the network using the same ring
number (source routing)
lIncludes all ports (by default) within a stack of
DeskStreams
nBridge Relay Function (BRF)
lAllows bridging between CRF and ports on different
ring numbers
lEquivalent to an IEEE SRT switch
The CRF manages all the basic ports including a ‘virtual’ port which
gives a link to the BRF interface and any ports which have been
transferred to that interface.
Ports within the CRF all use the same ring number (although they are
not in a ring - this is a switched environment). This allows an SR
frame (in an SR network) to find the correct DeskStream stack; the
CRF will sort out, from its Address/Descriptor table, which port to
pass the frame to.
The BRF allows us to take some ports out of the CRF and assign a
different ring number to each. The BRF manages the switching
between these ports and - via the CRF - to the basic ports.