Brocade Communications Systems CNA, HBA 415 Benutzerhandbuch
24
Brocade Adapters Administrator’s Guide
53-1001256-01
Buffer credits
4
Buffer credits
Buffer-to-buffer credit flow control is implemented to limit the amount of data a port sends, based
on the number and size of the frames sent from that port. This scheme allows Fibre Channel to be
self-throttling, thereby allowing it to establish a reliable connection without the need to
accommodate dropped frames due to congestion. Buffer credit limits between each device and the
fabric are communicated at the time of fabric login. One buffer credit allows a device to send one
frame of data (typically 1 or 2 KB). Buffer credits cannot be configured on an adapter.
on the number and size of the frames sent from that port. This scheme allows Fibre Channel to be
self-throttling, thereby allowing it to establish a reliable connection without the need to
accommodate dropped frames due to congestion. Buffer credit limits between each device and the
fabric are communicated at the time of fabric login. One buffer credit allows a device to send one
frame of data (typically 1 or 2 KB). Buffer credits cannot be configured on an adapter.
The default BB Credit is 1. The baseline for the calculation is one credit per kilometer at 2 Gbps.
This yields the following values for 10 km:
This yields the following values for 10 km:
•
5 credits per port at 1 Gbps
•
10 credits per port at 2 Gbps
•
20 credits per port at 4 Gbps
•
40 credits per port at 8 Gbps
Refer to the “Extended Fabrics concepts and planning” section of the Fabric OS Administrator’s
Guide for detailed information about buffer credits.
Guide for detailed information about buffer credits.
Basic port configuration
For each port, you can configure the following parameters using the Basic Port Configuration dialog
box, the Brocade Command Line utility (BCU), or both.
box, the Brocade Command Line utility (BCU), or both.
lists the features and configuration
options.
TABLE 7
Basic port configuration options
Port configuration parameter
Configurable using
the GUI
the GUI
Configurable using
the BCU
the BCU
For more information
Port logging level
1
Yes
Yes
Configure speed (HBA only)
Yes
Yes
Frame data field size
Yes
Yes
Persistent Binding
Note: The persistent binding option is
available on Windows platforms only.
Note: The persistent binding option is
available on Windows platforms only.
Yes
Yes
QoS (HBA only)
Yes
Yes
MPIO mode (HBA only)
Yes
Yes
Path Time Out
2
Yes
Yes
Target Rate Limiting (HBA only)
Yes
Yes
Boot over SAN (HBA only)
Yes
Yes
Boot code image upload (HBA only)
Yes
Yes
1
If an Ethernet port is selected, the Basic Port Configuration dialog displays an additional feature called
“Eth Logging Level.”
2
Path Time Out is available only when MPIO is disabled.