HP Fabric OS 7.1.0, Administrator'S Manual

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Fabric OS Administrator’s Guide 553
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Configuring an extended ISL
23
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Dynamic Mode (LD) — LD calculates buffer credits based on the distance measured during
port initialization. Brocade switches use a proprietary algorithm to estimate distance across an
ISL. The estimated distance is used to determine the buffer credits required in LD (dynamic)
extended link mode based on a maximum Fibre Channel payload size of 2,112 bytes. You can
place an upper limit on the calculation by providing a
desired_distance value. Fabric OS
confines user entries to no larger than what it has estimated the distance to be. When the
measured distance is more than the specified desired distance, the desired distance (the
smaller value) is used in the calculation.
•
Static Mode (LS) - LS calculates a static number of buffer credits based only on a user-defined
desired_distance value. LS mode also assumes that all FC payloads are 2112 bytes. Specify
LS mode to configure a static long-distance link with a fixed buffer allocation greater than 10
km.
Configuring an extended ISL
Before configuring an extended ISL, ensure that the following conditions are met:
•
The ports on both ends of the ISL are operating at the same port speed, and can be configured
for the same
distance_level without compromising local switch performance.
NOTE
A long-distance link also can be configured to be part of a trunk group. Two or more
long-distance links in a port group form a trunk group when they are configured for the same
speed and distance, and their link distances are nearly equal. For information on trunking
concepts and configurations, refer to
Chapter 22, “Managing Trunking Connections” .
•
Only qualified Brocade SFPs are used. Only Brocade-branded or certain Brocade-qualified
SFPs are supported.
1. Connect to the switch and log in using an account assigned to the admin role.
2. Enter the switchDisable command.
3. Enter the configure command to set the switch fabric-wide configurations. You can set the
following fabric-wide settings:
(* = multiplication symbol)
4. For 8-Gbps platforms only, enter the portCfgFillword command to set ARB as the fill word.
portcfgfillword [ slot /] port , mode
The mode parameter in this command should be set to 3 if the vc_translation_link_init
parameter in the portCfgLongDistance command (in the next step) is set to 1.
5. Enter the portCfgLongDistance command.
Field Type Default Range
Domain Number 1 Varies
R_A_TOV Number 10000 E_D_TOV * 2 to 120000
E_D_TOV Number 2000 1000 to R_A_TOV/2
WAN_TOV Number 0 0 to R_A_TOV/4
MAX_HOPS Number 7 7 to 19