Technical data

11-4 Fabric OS Administrator’s Guide
Publication Number: 53-0000518-09
Choosing an Extended ISL Mode
11
Table 11-3 lists the extended ISL modes for switches that have a Condor ASIC.
Table 11-3 Extended ISL Modes: Switches with Condor ASIC
For dynamic long distance links, you can approximate the number of buffer credits using the following
formula:
Buffer credits = [(distance in km) * (data rate) * 1000] / 2112
The data rate is 1.0625 for 1 Gbit/sec, 2.125 for 2 Gbit/sec, and 4.25 for 4 Gbit/sec and Fibre Channel.
This formula provides the minimum number of credits that will be allocated to a given port; the actual
number will likely be higher.
Configuring External Ports
The number of ports that can be configured per port group for each switch depends on both port speed
and distance. The following sections specify the number of external ports available for each switch at a
specific port speed and distance.
SilkWorm 3016
Extended links are supported on the two external ports (0 and 15). Configuring extended links on these
ports might affect internal ports 9 and 10 because of shared buffers.
When configuring external ports for long distance, both port speed (1 or 2 Gbit/sec) and distance setting
(L0.5, L1, L2, and LD) must be considered.
For external ports operating at 2 Gbit/sec, the following restrictions should be observed:
• Setting two ports to L2 (60 km) is not allowed.
• Setting one external port to L2 (60 km) and the other external port to L0.5 (25 km) disables two
internal ports.
Mode Buffer Allocation Distance
@ 1 Gbit/
sec
Distance
@ 2 Gbit/
sec
Distance
@ 4 Gbit/
sec
Earliest
Fabric OS
Release
Extended
Fabrics
License
Required?
1 Gbit/
sec
2 Gbit/
sec
4 Gbit/
sec
L0 5 (26)
a
a. For each data channel (in this case, there are 4) there are 5 credits, plus 6 extra credits.
5 (26) 2.5 km 10 km 5 km 2 km All No
LE 11 16 10 km n/a 5 km 5 km v3.x, v4.x No
L0.5 18 31 56 25 km 25 km 25 km v3.1.0, v4.1.0,
v4.x, 5.x
Yes
L1 31 56 106 50 km 50 km 50 km All Yes
Ll2 56 106 206 100 km 100 km 100 km All Yes
LD
b
b. The dynamic long-distance mode (LD) automatically configures the number of buffer credits required, based on the actual link distance.
Auto Auto Auto Auto Auto Auto v3.1.0, v4.1.0,
v4.4.0, 5.x
(depending on
the model)
Yes