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Cisco MDS 9000 Family NX-OS Interfaces Configuration Guide
OL-29284-01, Release 6.x
Chapter 2 Configuring Interfaces
Information About Interfaces
A graceful shutdown is not possible in the following situations:
• If you physically remove the port from the switch.
• If in-order delivery (IOD) is enabled (for information about IOD, refer to the Cisco MDS 9000
Family NX-OS Fabric Configuration Guide).
• If the Min_LS_interval interval is higher than 10 seconds. For information about FSPF global
configuration, refer to the Cisco MDS 9000 Family NX-OS Fabric Configuration Guide.
Note This feature is only triggered if both switches at either end of this E port interface are MDS switches and
are running Cisco SAN-OS Release 2.0(1b) or later, or MDS NX-OS Release 4.1(1a) or later.
Port Administrative Speeds
By default, the port administrative speed for an interface is automatically calculated by the switch.
For internal ports on the Cisco Fabric Switch for HP c_Class BladeSystem and Cisco Fabric Switch for
IBM BladeCenter, a port speed of 1 Gbps is not supported. Auto-negotiation is supported between 2
Gbps and 4 Gbps only. Also, if the BladeCenter is a T chassis, then port speeds are fixed at 2 Gbps and
auto-negotiation is not enabled.
Autosensing
Autosensing speed is enabled on all 4-Gbps and 8-Gbps switching module interfaces by default. This
configuration enables the interfaces to operate at speeds of 1 Gbps, 2 Gbps, or 4 Gbps on the 4-Gbps
switching modules, and 8 Gbps on the 8-Gbps switching modules. When autosensing is enabled for an
interface operating in dedicated rate mode, 4 Gbps of bandwidth is reserved, even if the port negotiates
at an operating speed of 1 Gbps or 2 Gbps.
To avoid wasting unused bandwidth on 48-port and 24-port 4-Gbps and 8-Gbps Fibre Channel switching
modules, you can specify that only 2 Gbps of required bandwidth be reserved, not the default of 4 Gbps
or 8 Gbps. This feature shares the unused bandwidth within the port group provided that it does not
exceed the rate limit configuration for the port. You can also use this feature for shared rate ports that
are configured for autosensing.
Tip When migrating a host that supports up to 2-Gbps traffic (that is, not 4 Gbps with autosensing
capabilities) to the 4-Gbps switching modules, use autosensing with a maximum bandwidth of 2 Gbps.
When migrating a host that supports up to 4-Gbps traffic (that is, not 8 Gbps with autosensing
capabilities) to the 8-Gbps switching modules, use autosensing with a maximum bandwidth of 4 Gbps.
Frame Encapsulation
The switchport encap eisl command only applies to SD port interfaces. This command determines the
frame format for all frames transmitted by the interface in SD port mode. If the encapsulation is set to
EISL, all outgoing frames are transmitted in the EISL frame format, regardless of the SPAN sources.
The switchport encap eisl command is disabled by default. If you enable encapsulation, all outgoing
frames are encapsulated, and you will see a new line (Encapsulation is eisl) in the show interface
SD_port_interface command output. See the Cisco MDS 9000 Family NX-OS System Management
Configuration Guide.
