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Cisco IE 2000 Switch Software Configuration Guide
OL-25866-01
Chapter 15 Configuring Interface Characteristics
Information About Configuring Interface Characteristics
Note Ports on the switch can receive, but not send, pause frames.
You use the flowcontrol interface configuration command to set the interface’s ability to receive pause
frames to on, off, or desired. The default state is off.
When set to desired, an interface can operate with an attached device that is required to send
flow-control packets or with an attached device that is not required to but can send flow-control packets.
These rules apply to flow control settings on the device:
• receive on (or desired)—The port cannot send pause frames but can ope rate with an attached device
that is required to or can send pause frames; the port can receive pause frames.
• receive off—Flow control does not operate in eith er direction. In case of congestion, no indication
is given to the link partner, and no pause frames are sent or received by either device.
Auto-MDIX on an Interface
When automatic medium-dependent interface crossover (auto-MDIX) is enabled on an interface, the
interface automatically detects the required cable connection type (straight through or crossover) and
configures the connection appropriately. When connecting switches without the auto-MDIX feature, you
must use straight-through cables to connect to devices such as servers, workstations, or routers and
crossover cables to connect to other switches or repeaters. With auto-MDIX enabled, you can use either
type of cable to connect to other devices, and the interface automatically corrects for any incorrect
cabling. For more information about cabling requirements, see the hardware installation guide.
Auto-MDIX is enabled by default. When you enable auto-MDIX, you must also set the interface speed
and duplex to auto so that the feature operates correctly.
Auto-MDIX is supported on all 10/100 and 10/100/1000-Mb/s i nterfaces. It is not supported on
1000BASE-SX or -LX SFP module interfaces.
SVI Autostate Exclude
Configuring SVI autostate exclude on an access or trunk port in an SVI excludes that port in the
calculation of the status of the SVI (up or down line state) even if it belongs to the same VLAN. When
the excluded port is in the up state, and all other ports in the VLAN ar e in the down state, the SVI state
is changed to down.
At least one port in the VLAN should be up and not excluded to keep the SVI line state up. You can use
this command to exclude the monitoring port status when determining the status of the SVI.
System MTU
The default maximum transmission unit (MTU) size for frames received and transmitted on all interfaces
is 1500 bytes. You can increase the MTU size for all interfaces operating at 10 or 100 Mb/s by using the
system mtu global configuration command. You can increase the MTU size to support jumbo frames on
all Gigabit Ethernet interfaces by using the system mtu jumbo global configuration command.
You can change the MTU size for routed ports by using the system mtu routing global configuration
command.