Nortel Networks OPTera Metro 3500 - Manual (Page 61)

Operation, administration, and maintenance (OAM) features 2-23
Planning and Ordering Guide—Part 1 of 2 NTRN10AN Rel 12.1 Standard Iss 1 Apr 2004
Figure 2-10
BLSR ring switch example
EX1243p
W
P
9
Legend
Add/drop multiplexer
One fiber divided into
working and protection
bandwidth
W
P = Working traffic
= Protection traffic Long path
SD/4/3/L/bridged and switched
W
W
W
W
P
P
P
P
Bridged and
Switched
state
Bridged
state
W
W
W
W
P
P
P
P
W
W
W
W
P
P
4 3
1 2
P
P
W
W
P
P
W
W
P
P
Totally
decoupled
'Bridged and
Switched' state
'Bridged and
Switched' state
'Pass-through'
state
'Pass-through'
state
Node 3 and 4 state change detail