3Com E4500-24 Cli Configuration Manual page 321

Figure 1-3 The format of an EAPoL packet
In an EAPoL packet:
The PAE Ethernet type field holds the protocol identifier. The identifier for 802.1x is 0x888E.
The Protocol version field holds the version of the protocol supported by the sender of the EAPoL
packet.
The Type field can be one of the following:
00: Indicates that the packet is an EAP-packet, which carries authentication information.
01: Indicates that the packet is an EAPoL-start packet, which initiates the authentication.
02: Indicates that the packet is an EAPoL-logoff packet, which sends logging off requests.
03: Indicates that the packet is an EAPoL-key packet, which carries key information.
04: Indicates that the packet is an EAPoL-encapsulated-ASF-Alert packet, which is used to
support the alerting messages of Alerting Standards Forum (ASF).
The Length field indicates the size of the Packet body field. A value of 0 indicates that the Packet
Body field does not exist.
The Packet body field differs with the Type field.
Note that EAPoL-Start, EAPoL-Logoff, and EAPoL-Key packets are only transmitted between the
supplicant system and the authenticator system. EAP packets are encapsulated by RADIUS protocol to
allow them successfully reach the authentication servers. Network management-related information
(such as alarming information) is encapsulated in EAPoL-Encapsulated-ASF-Alert packets, which are
terminated by authenticator systems.
The format of an EAP packet
For an EAPoL packet with the value of the Type field being EAP-packet, its Packet body field is an EAP
packet, whose format is illustrated in
Figure 1-4 The format of an EAP packet
In an EAP packet:
The Code field indicates the EAP packet type, which can be Request, Response, Success, or
Failure.
The Identifier field is used to match a Response packet with the corresponding Request packet.
Figure 1-4.
1-4