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Catalyst 3750 SwitchSoftware Configuration Guide
OL-8550-09
Chapter12 Configuring Interface Characteristics
Understanding Interface Types
is a monitoring port, you might configure autostate exclude on that port so that the VLAN goes down
when all other ports go down. When enabled on a port, autostate exclude applies to all VLANs that are
enabled on that port.
The VLAN interface is brought up when one Layer 2 port in the VLAN has had time to converge
(transition from STP listening-learning state to forwarding state). This prevents features such as routing
protocols from using the VLAN interface as if it were fully operational and minimizes other problems,
such as routing black holes. For information about configuring autostate exclude, see the “Configuring
SVI Autostate Exclude” section on page12-27.
EtherChannel Port Groups
EtherChannel port groups treat multiple switch ports as one switch port. An EtherChannel port group
acts as a single logical port for high-bandwidth connections between switches or between switches and
servers. An EtherChannel balances the traffic load across the links in the channel. If a link within the
EtherChannel fails, traffic previously carried over the failed link changes to the remaining links. You can
group multiple trunk ports into one logical trunk port, group multiple access ports into one logical access
port, group multiple tunnel ports into one logical tunnel port, or group multiple routed ports into one
logical routed port.
Most protocols operate over either single ports or aggregated switch ports and do not recognize the
physical ports within the port group. The DTP, the Cisco Discovery Protocol (CDP), and the Port
Aggregation Protocol (PAgP) operate only on physical ports.
When you configure an EtherChannel, you create a port-channel logical interface and assign an interface
to the EtherChannel. Use the channel-group interface configuration command to dynamically create the
port-channel logical interface. This command binds the physical and logical ports together.
For Layer 3 interfaces, you manually create the logical interface by using the interface port-channel
global configuration command. Then you manually assign an interface to the EtherChannel by using the
channel-group interface configuration command.
For more information, see Chapter36, “Configuring EtherChannels and Link-State Tracking.”
10-Gigabit Ethernet Interfaces
The Catalyst 3750G-16TD switch has one 10-Gigabit Ethernet interface. The switch uses a 10-Gigabit
Ethernet XENPAK module to establish connections to networks.
The 10-Gigabit Ethernet interface only operates in full-duplex mode. The interface can be configured as
a switched port or a routed port. A stack of Catalyst 3750 switches can have up to nine 10-Gigabit
Ethernet interfaces. A cross-stack EtherChannel supports up to two 10-Gigabit module ports.
For the latest information about XENPAK modules supported by the switch, see the release notes.
For more information about XENPAK modules, see your XENPAK module documentation.
Note The 10-Gigabit Ethernet module ports are referred to as 10-Gigabit Ethernet XENPAK modules in the
hardware installation guide.