H3C Technologies H3C S3100 Series Switches - Manual (Page 277)

Operation Manual – 802.1x
H3C S3100-52P Ethernet Switch Chapter 1 802.1x Configuration
1-4
through LANs, EAP protocol packets are encapsulated in EAPoL format. The following
figure illustrates the structure of an EAPoL packet.
PAE Ethernet type Protocol version Length
0 2 3 4
Packet body
6 N
Type PAE Ethernet type Protocol version Length
0 2 3 4
Packet body
6 N
Type
Figure 1-3
The format of an EAPoL packet
In an EAPoL packet:
z
The PAE Ethernet type field holds the protocol identifier. The identifier for 802.1x is
0x888E.
z
The Protocol version field holds the version of the protocol supported by the
sender of the EAPoL packet.
z
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 ASF (alerting standards forum).
z
The Length field indicates the size of the Packet body field. A value of 0 indicates
that the Packet Body field does not exist.
z
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.
II. 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.