Technical data

11-2 Fabric OS Administrator’s Guide
Publication Number: 53-0000518-09
Fabric Considerations
11
A buffer-limited port can come online with fewer buffer credits allocated than its configuration
specifies, allowing it to operate at a reduced bandwidth instead of being disabled for lack of buffers.
Buffer-limited operation is supported for the L0 and LD extended ISL modes only, and is persistent
across reboots, switch disabling and enabling, and port disabling and enabling.
Fabric Considerations
Consider these items that affect the fabric when you configure extended ISLs:
• The extended link configuration mode, L2 can reach 100 km at a speed of 2Gbit/sec between
Brocade Fabric OS v4.x switches. However, it only supports a distance of up to 60 km if the link is
established between Brocade Fabric OS v3.x and 4.x switches.
• The standard distance and long-distance ISL modes cannot be enabled at the same time.
• Balance the number of long-distance ISL connections and core-to-edge ISL connections within a
switch. Configuring long-distance ISLs between core and edge switches is possible, but is not a
recommended practice.
• Starting with Fabric OS v4.4.0, VC translation link initialization (an option of the
portCfgLongDistance command) is enabled by default for long-distance links. For previous
Fabric OS versions that support this option, it was disabled by default. To avoid inconsistency in
the fabric, make sure that this value is enabled on both ends of the link. To connect to switches
running Fabric OS versions earlier than v4.0.2 and v3.0.2c, make sure that VC translation link
initialization is disabled because these versions do not support it.