# Extending SANbox Port Credits

Each switch port is has a data buffer with an 8 credit capacity; that is, 8 maximum sized frames. For fibre optic cables, this enables full bandwidth over a distance of 13 kilometers with no loss in performance. Buffer credits can be extended for G_Ports and E_Ports to maintain performance over longer cable lengths. You can configure a recipient G_Port or E_Port to acquire the 8 buffer credits each from 1, 2, or 3 donor ports. For example, the recipient port and one donor ports yields16 credits, two donor ports yields 24 credits, three donor ports yields 32 credits.

To extend buffer credits, the switch must be configured properly. Credits can be extended only for G_Ports and E_Ports. The recipient port occupies the lowest numbered port in an ASIC group. ASIC port groups are as follows: 0-3, 4-7, 8-11, 12-15. For example, you can extend credits to recipient port 0 from donor ports 1, 2, and 3.

To extend SANbox port buffer credits, do the following:

1. Open the Port menu and select Extended Credits to open the Extended Credits dialog.

2. Choose the recipient port (0, 4, 8, or 12) and select the extended credit mode from the pull-down menu. The disabled donor ports are listed to the right.

* Ext8 extends 8 credits to the recipient port for a total of 16. One donor port is disabled.

* Ext16 extends 16 credits to the recipient port for a total of 24. Two donor ports are disabled.

* Ext24 extends 24 credits to the recipient port for a total of 32. Three donor ports are disabled.

3. Click the OK button.