Configuring LAN Interfaces
Configuring an Ethernet or Fast Ethernet Interface
Specifying an Ethernet or Fast Ethernet Interface
To specify an Ethernet interface and enter interface configuration mode, use one of the following commands in global configuration mode:
Command |
| Purpose |
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| |
interface ethernet number | Begins interface configuration. | |
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interface ethernet slot/port | Begins interface configuration for the Cisco 7200 and Cisco 7500 series | |
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| routers. |
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interface ethernet |
| Begins interface configuration for Cisco 7500 series routers. |
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| |
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interface fastethernet | number | Begins interface configuration for the Cisco 4000 series with a Fast Ethernet |
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| NIM installed. |
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interface fastethernet | slot/port | Specifies a Fast Ethernet interface and enters interface configuration mode on |
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| the Cisco 7200 series routers. |
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interface fastethernet |
| Specifies a Fast Ethernet interface and enters interface configuration mode on |
| the Cisco 7500 series routers. | |
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|
Use the show interfaces fastethernet command to display the Fast Ethernet slots and ports. The Fast Ethernet NIM and the FEIP default to
Specifying an Ethernet Encapsulation Method
Currently, there are three common Ethernet encapsulation methods:
•The standard ARPA Ethernet Version 2.0 encapsulation, which uses a
•SAP IEEE 802.3 encapsulation, in which the type code becomes the frame length for the IEEE 802.2 LLC encapsulation (destination and source Service Access Points, and a control byte)
•The SNAP method, as specified in RFC 1042, “Standard for the Transmission of IP Datagrams Over IEEE 802 Networks,” which allows Ethernet protocols to run on IEEE 802.2 media
The encapsulation method you use depends upon the routing protocol you are using, the type of Ethernet media connected to the router or access server, and the routing or bridging application you configure.
Establish Ethernet encapsulation of IP packets by using one of the following commands in interface configuration mode:
Command | Purpose |
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encapsulation arpa | Selects ARPA Ethernet encapsulation. |
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encapsulation sap | Selects SAP Ethernet encapsulation. |
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encapsulation snap | Selects SNAP Ethernet encapsulation. |
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For an example of selecting Ethernet encapsulation for IP, see the “Ethernet Encapsulation Enablement Example” section.
Cisco IOS Interface Configuration Guide
