Connecting Interfaces; Using The Interface Command - Cisco Catalyst 2950 Software Configuration Manual

Using the Interface Command

When you configure an EtherChannel, you create a port-channel logical interface and assign an interface
to the EtherChannel. For Layer 2 interfaces, the logical interface is dynamically created. You manually
assign an interface to the EtherChannel by using the channel-group interface configuration command.
This command binds the physical and logical ports together. For more information, see
"Configuring EtherChannels."

Connecting Interfaces

Devices within a single VLAN can communicate directly through any switch. Ports in different VLANs
cannot exchange data without going through a routing device or routed interface.
With a standard Layer 2 switch, ports in different VLANs have to exchange information through a router.
In the configuration shown in
it must go from Host A to the switch, to the router, back to the switch, and then to Host B.
Figure 10-1
Using the Interface Command
To configure a physical interface (port), use the interface global configuration command to enter interface
configuration mode and to specify the interface type, slot, and number.
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Catalyst 2950 and Catalyst 2955 Switch Software Configuration Guide
10-4
Figure
Connecting VLANs with Layer 2 Switches
Host A
VLAN 20
Type—Fast Ethernet (fastethernet or fa) for 10/100 Ethernet, Gigabit Ethernet (gigabitethernet or
gi), or LRE (longreachethernet or lo).
Slot—The slot number on the switch (always 0 on this switch).
Port number—The interface number on the switch. The port numbers always begin at 1, starting with
the leftmost port when facing the front of the switch, for example, fastethernet0/1, fastethernet0/2.
If there is more than one interface type (for example, 10/100 ports and Gigabit Ethernet ports), the
port number restarts with the second interface type: gigabitethernet0/1, gigabitethernet0/2.
Chapter 10
10-1, when Host A in VLAN 20 sends data to Host B in VLAN 30,
Cisco router
Switch
Host B
VLAN 30
Configuring Interface Characteristics
Chapter 30,
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