Nortel Meridian Meridian 1 Feature Description And Administration page 926

Page 926 of 1814
Figure 72
Transit node operation
Node A
call is routed to next
available alternate route
553-2901-301 Standard 9.00 January 2002
ISDN QSIG Alternate Routing
QSIG
An attempt is made to find a free alternate route until all of the alternate
routes, as defined in LD 86 (refer to the ROUT prompt on page 932), are
tried. If no free alternate route is available, the congestion message
information is sent from node B to the originating node A, where the QSIG
Alternate Routing functionality is activated. If no alternate routes are found,
the call receives network blocking treatment, as defined by prompt NBLK in
LD 15, as part of the initial customer configuration.
If SBOC = RRO, the congestion information is passed back from transit
node B to the originating node A. At node A, QSIG Alternate Routing is
activated in an attempt to find an alternate route to set up the call from
node A, to node B, to node D, to node C.
Node B
QSIG
call clearing message
call is established using
Node D
Private
Exchange
or
C e n t r a l
O f f i c e
Node C
alternate route
553_8380