Buffer Credit Recovery - HP A7533A - Brocade 4Gb SAN Switch Base Administrator's Manual

Table 83 Supported Distances (continued)
Switch/blade model
HP StorageWorks 400
Multi-Protocol Router
HP StorageWorks 4/256 SAN
Director 16 Port 4Gb Blade
HP StorageWorks B-Series iSCSI
Director Blade
HP StorageWorks 4/256 SAN
Director 32 Port 4Gb Blade
HP StorageWorks 4/256 SAN
Director 48 Port 4Gb Blade
HP StorageWorks SAN Director
48 Port 4Gb FC blade
HP StorageWorks SAN Director
16 Port 8Gb FC blade
HP StorageWorks SAN Director
32 Port 8Gb FC blade
HP StorageWorks SAN Director
48 Port 8Gb FC blade
B-Series Multi-Protocol Router
Blade
NOTE: QoS requires an additional 14 buffer credits per active port so maximum supported distances may
be lower.
The HP StorageWorks SAN Director 6 Port 10Gb FC blade supports a maximum distance of 100 km on
each of the 6x 10 Gb/s ports.
To get an estimated maximum equally distributed distance for n number of ports at a particular ("X")
speed, divide the 1-port maximum distance of the switch at X speed by n. For example, for three ports
running at 2 Gb/s on HP StorageWorks 8/8 and 8/24 SAN Switches, the maximum equally distributed
distance is: 486 / 3 = 164 km.

Buffer credit recovery

Buffer credit recovery does not require configuration. This feature allows links to recover after R_RDYs are
lost when the credit recovery logic is enabled. The buffer credit recovery feature also maintains
performance. If a credit is lost, a recover attempt is initiated. During link reset, the frame and credit loss
counters are reset without performance degradation.
This feature is supported only on E_Ports that are configured for long distance and are connected between
the following switch or blade models:
• HP StorageWorks 8/8 and 8/24 SAN Switches, HP StorageWorks 8/40 SAN Switch, HP
StorageWorks 8/80 SAN Switch
• HP StorageWorks SAN Director 16 Port 8Gb FC blade, HP StorageWorks SAN Director 32 Port 8Gb
FC blade, HP StorageWorks SAN Director 48 Port 8Gb FC blade
If a long-distance E_Port from one of these supported switches/blades is connected to any other switch or
blade type, the buffer credit recovery feature is disabled.
Maximum supported distances with 2112 Byte Frame
(1-port allocated all unreserved buffer credits) in km @
1 Gb/s 2 Gb/s
500 250
500 250
500 250
500 250
500 250
500 250
2588 / 2780 1294 / 1390
2588 / 2780 1294 / 1390
2460 / 2652 1230 / 1326
500 250
Size
4 Gb/s 8 Gb/s
100 N/A
100 N/A
100 N/A
100 N/A
100 N/A
100 N/A
647 / 695 324 / 348
647 / 695 324 / 348
615 / 663 308 / 332
100 N/A
Fabric OS 6.2 administrator guide 429