3Com 2928 - Baseline Plus Switch PWR, User Manual

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1-4
EAP packet format
An EAP-Packet-type EAPOL frame carries an EAP packet in its Packet body field. The format of the
EAP packet is shown in
Figure 1-4 .
Figure 1-4
EAP packet format
Code: Type of the EAP packet, which can be Request, Response, Success, or Failure.
z
An EAP success/failure packet has no Data field, and has a length of 4.
z
An EAP Request/Response packet has a Data field in the format shown in Figure 1-5 . The Type
field indicates the EAP authentication type. A value of 1 represents Identity, indicating that the
packet is for querying the identity of the client. A value of 4 represents MD5-Challenge, which are
similar to the PPP CHAP protocol.
Figure 1-5
Format of the Data field in an EAP request/response packet
Identifier: Helps match responses with requests.
Length: Length of the EAP packet, including the Code, Identifier, Length, and Data fields, in bytes.
Data: Content of the EAP packet. Its format is determined by the Code field.
EAP over RADIUS
Two attributes of RADIUS are intended for supporting EAP authentication: EAP-Message and
Message-Authenticator. For information about RADIUS packet format, refer to
RADIUS Configuration
.
EAP-Message
The EAP-Message attribute is used to encapsulate EAP packets. Figure 1-6 shows its encapsulation
format. The value of the Type field is 79. The String field can be up to 253 bytes long. If the EAP packet
is longer than 253 bytes, it can be fragmented and encapsulated into multiple EAP-Message attributes.
Figure 1-6
Encapsulation format of the EAP-Message attribute
0 15
Type String
7
Length
N
EAP packets