Nortel Networks OPTera Metro 3500 - Manual (Page 136)

2-98 Operation, administration, and maintenance (OAM) features
OPTera Metro 3500 Multiservice Platform NTRN10AN Rel 12.1 Standard Iss 1 Apr 2004
If congestion should occur at the destination storage device, it would begin
withholding R_RDYs from the egress OPTera Metro 3500. All transmitted
Fibre Channel frames are buffered in the egress OPTera Metro 3500 card
memory. When a certain memory threshold is reached, a flow control signal is
sent to the ingress OPTera Metro 3500 to stop the transmission of Fibre
Channel frames. Upon receipt of these flow control messages, the ingress
OPTera Metro 3500 would in turn withhold R_RDYs from the source storage
device. This mechanism ensures that downward pressure is cascaded upstream
to the source of the traffic until congestion abates.
Table 2-20 on page 2-98 , lists the sample distances based on the available
WAN bandwidth.
Table 2-20
Fibre Channel extended reach sample distances
STS1-nv Round Trip Delay
( µs)
See Note 1
Distance
(kms)
See Note 2
STS3c-nv Round Trip Delay
( µs)
Distance
(kms)
See Note 2
19
See Note 3
9870 987 6
See Note 3
9870 987
18 10160 1016 5 11820 1182
17 10760 1076 4
See Note 3
14770 1477
16 11430 1143 3 19690 1969
15 12190 1219 2 29540 2954
14 13060 1306 1
See Note 3
59080 5908
13 14070 1407
12 15240 1524
11 16620 1662
10 18290 1829
9 20320 2032
8 22860 2286
7 26120 2612
6 30480 3048
5 36570 3657
4 45710 4571