HP StorageWorks 2/64 - Core Switch Command Reference Manual page 125

MAX_HOPS
NOTE: The R_A_TOV, E_D_TOV, WAN_TOV, and MAX_HOPS configuration parameters are
inter-related. Assigning a specific value to one or more of these parameters can change the range of
allowed values that can be assigned to the other parameters. As a result, the user might not be able to set
all the values within the range displayed against each parameter. To reduce problems, the configuration
utility validates the modified parameter values and prompts the user to re-enter some values, if the
validation check fails.
Data Field Size
Sequence-Level Switching
Disable Device Probing
Suppress Class F Traffic
Switch PID Format
Per-frame Route Priority
Long Distance Fabric
Maximum hops (MAX_HOPS) is an integer that denotes the
upper limit on the number of hops a frame might have to traverse
to reach any destination port from any source port across the
fabric.
The data field size specifies the largest possible value, in bytes, and
advertises this value to other switches in the fabric during construction
of the fabric as well as to other devices when they connect to the
fabric. Setting this to a value smaller than 2112 might result in
decreased performance.
When sequence-level switching is set to 1, frames of the same
sequence from a particular source are transmitted as a group. When
this feature is set to 0, frames are transmitted interleaved among
multiple sequences.
Under normal conditions, sequence-level switching should be disabled
for better performance. However, some host adapters have
performance issues when receiving interleaved frames from multiple
sequences. When there are such devices attached to the fabric,
sequence-level switching should be enabled.
When disable device probing is set to 1, devices that do not register
with the name server are not present in the name server data base. Set
this mode only if the switch N_Port discovery process (PLOGI, PRLI,
INQUIRY) causes an attached device to fail.
When this mode is set to 1, all Class F interswitch frames are
transmitted as Class 2 frames. This is to support remote fabrics that
involve ATM gateways, which don't support class F traffic.
The formats are as follows:
0 Native PID format (16 based, 16 port format), for fabrics
with legacy low-count-port switches.
1 Core PID format (0 based, 256 port format), preferred
mode for mixed fabrics with legacy and new switches.
2 Extended edge PID format (16 based, 256 port format),
used in mixed fabrics with legacy and new switches to
avoid need to reboot host systems when static PID binded is
used.
In addition to the eight virtual channels used in frame routing priority,
support is also available for per-frame-based prioritization when this
value is set. When Per-frame Route Priority is set to 1, the virtual
channel ID is used in conjunction with a frame header to form the final
virtual channel ID.
When this mode is set to 1, ISLs in a fabric can be up to 100 km long.
The exact distance level is determined by the per-port configuration on
the E_Ports of each ISL. Both E_Ports in an ISL must be configured to run
the same long-distance level; otherwise, the fabric will be segmented.
The Extended Fabric License is required to set this mode.
Fabric OS 5.x command reference guide 125