Ethernet and Fast Ethernet Interfaces
Give an Ethernet or Fast Ethernet
interface an IP address, and it’s ready to go. It’s a
good idea to give the interface a description, but that’s not
required. Also, as with all interfaces, don’t forget the
no
shutdown
command. For Fast
Ethernet interfaces, you can also specify the interface
speed and whether
it’s operating at full or half duplex:
interface Ethernet0 description Internal Office Network ip address 10.10.1.1 255.255.255.248 no shutdown interface FastEthernet1 description Fast Network for fileservers ip address 10.10.1.17 255.255.255.248 ! Set the speed to 100 (which is the default) speed 100 ! Set the duplex to full duplex full no shutdown
Ethernet Encapsulation
By default, an Ethernet uses
ARPA encapsulation
(standard Ethernet Version 2.0). However, you can specify another
encapsulation type using the encapsulation
command. For example:
interface ethernet 0 encapsulation arpa ip address 10.10.1.10 255.255.255.248
The possible encapsulation types are shown in Table 5-3.
Table 5-3. Ethernet encapsulation types
Keyword |
Encapsulation type |
---|---|
|
Standard Ethernet Version 2.0 |
|
IEEE 802.3 Encapsulation |
|
IEEE 803.3 Encapsulation per RFC 1042 |
All the devices connected to an Ethernet must share the same encapsulation type; if they do not, they will not be able to communicate. If you’re not sure of the encapsulation type, you’re probably using ARPA.
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