Cisco Nexus 5000 Series Switch Fabric Manager Software Configuration Guide, NX-OS 4.0 (OL-16598-01, June 2008)

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10-7
Nexus 5000 Series Switch Fabric Manager Software Configuration Guide
OL-16598-01
Chapter 10 Configuring Fibre Channel Interfaces
Information About Fibre Channel Interfaces
Buffer-to-Buffer Credits
Buffer-to-buffer credits (BB_credits) are a flow-control mechanism to ensure that Fibre Channel
interfaces do not drop frames. BB_credits are negotiated on a per-hop basis.
In Nexus 5000 Series switches, the BB_credit mechanism is used on Fibre Channel interfaces but not on
virtual Fibre Channel interfaces. Virtual Fibre Channel interfaces provide flow control based on
capabilities of the underlying physical Ethernet interface.
The receive BB_credit value (fcrxbbcredit) may be configured for each Fibre Channel interface. In most
cases, you do not need to modify the default configuration.
Note The receive BB_credit values depend on the port mode, as follows:
• For physical Fibre Channel interfaces, the default value is 16 for F mode and E mode interfaces. This
value can be changed as required. The maximum value is 64.
Isolation due to ELP failure The port negotiation failed. Only E ports
and TE ports
Isolation due to ESC failure The port negotiation failed.
Isolation due to domain
overlap
The Fibre Channel domains (fcdomain) overlap.
Isolation due to domain ID
assignment failure
The assigned domain ID is not valid.
Isolation due to the other side
of the link E port isolated
The E port at the other end of the link is isolated.
Isolation due to invalid fabric
reconfiguration
The port is isolated due to fabric reconfiguration.
Isolation due to domain
manager disabled
The fcdomain feature is disabled.
Isolation due to zone merge
failure
The zone merge operation failed.
Isolation due to VSAN
mismatch
The VSANs at both ends of an ISL are different.
port channel administratively
down
The interfaces belonging to the SAN port channel are
down.
Only SAN
port channel
interfaces
Suspended due to incompatible
speed
The interfaces belonging to the SAN port channel have
incompatible speeds.
Suspended due to incompatible
mode
The interfaces belonging to the SAN port channel have
incompatible modes.
Suspended due to incompatible
remote switch WWN
An improper connection is detected. All interfaces in a
SAN port channel must be connected to the same pair
of switches.
Table 10-4 Reason Codes for Nonoperational States (continued)
Reason Code (long version) Description
Applicable
Modes