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
arpa	Standard Ethernet Version 2.0
isol	IEEE 802.3 Encapsulation
snap	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.