Huawei Quidway S3900 Series Operation Manual page 459

Operation Manual – 802.1x
Quidway S3900 Series Ethernet Switches-Release 1510
The Code field specifies the EAP packet type, which can be Request, Response,
Success, or Failure.
The Identifier field is used to match a Response packets with the corresponding
Request packet.
The Length field indicates the size of an EAP packet, which includes the Code,
Identifier, Length, and Data fields.
The Data field differs with the Code field.
A Success or Failure packet does not contain the Data field, so has the Length field of
4.
Figure 1-5 shows the Data field of Request and Response type packet.
Type
Figure 1-5 Data fields
The Type field specifies the EAP authentication type. A Type value of 1 indicates
Identity and that the packet is used to query the identity of the peer. A type value of
4 represents MD5-Challenge (similar to PPP CHAP) and indicates that the packet
includes query information.
The Type Date field differs according to different types of Request and Response
packets.
III. Newly added fields for EAP authentication
Two fields, EAP-message and Message-authenticator, are added to a RADIUS
protocol packet for EAP authentication. (Refer to the Introduction to RADIUS protocol
section in the AAA&RADIUS&RADIUS&HWTACACS&EAD Operation Manual for
format of a RADIUS protocol packet.)
The EAP-message field, shown in Figure 1-6, is used to encapsulate EAP packets. The
maximum size of the string field is 253 bytes. EAP packets with their size larger than
253 bytes are fragmented and stored in multiple EAP-message fields. The type code of
the EAP-message field is 79.
0 0
Type Type
Figure 1-6 The format of an EAP-message field
The Message-authenticator field, as shown in Figure 1-7, is used to prevent
unauthorized interception of access requesting packets during authentications using
CHAP, EAP, and so on. A packet with the EAP-message field must also have the
Type Data
2 2
1 1
Length Length
EAP packet EAP packet
Huawei Technologies Proprietary
1-5
Chapter 1 802.1x Configuration
String String