Administering Extended Fabrics; About Extended Link Buffer Allocation - HP StorageWorks 2/64 - Core Switch Administrator's Manual

7

Administering extended fabrics

This chapter contains the following information:
• About extended link buffer
• Configuring for long

About extended link buffer allocation

As the distance between switches and the link speed increases, additional buffer-to-buffer credits are
required to maintain maximum performance. The number of credits reserved for a port depends on the
switch model and on the extended ISL mode for which it is configured.
The Extended Fabric tab of the Switch Admin module displays information about the port speed,
long-distance setting, and buffer credits, as shown in
long-distance setting of a port. For detailed information on managing extended fabrics, see the HP
StorageWorks Fabric OS 5.x administrator guide.
The Extended Fabric tab provides the following information:
• Port Number
• Buffer Limited: 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.
• Port Speed, which is displayed as follows:
• 1G 1 Gbit/sec
• 2G 2 Gbit/sec
• 4G 4 Gbit/sec
• N1 Negotiated 1 Gbit/sec
• N2 Negotiated 2 Gbit/sec
• N4Negotiated 4 Gbit/sec
• Auto-Negotiation
• Buffer Needed/Allocated: The number of buffers needed and the number of buffers that are actually
allocated.
• Actual Distance: The actual distance, in kilometers, for the link.
• Desired Distance: Required for a port configured in LD mode (see
kilometers, for the link. This value is the upper limit for calculating buffer availability for the port. If the
measured distance is more than the specified desired distance, the port is allocated the number of
buffers required by the specified desired distance.
• Long Distance:
Extended Fabrics license.
allocation, page 75
distance, page 76
Table 9 describes the long-distance settings and identifies which settings require an
Figure 24. Use this tab to configure the
Table
Fabric OS 5.x Advanced Web Tools administrator guide
9), the desired distance, in
75