H3C Technologies H3C S12500-X Series Switches - Manual (Page 76)

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Value Type Description
0x02 EAPOL-Logoff
The client sends an EAPOL-Logoff message to tell the network access
device that it is logging off.
• Length—Data length in bytes, or length of the Packet body. If packet type is EAPOL-Start or
EAPOL-Logoff, this field is set to 0, and no Packet body field follows.
• Packet body—Content of the packet. When the EAPOL packet type is EAP-Packet, the Packet body
field contains an EAP packet.
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EAP over RADIUS
RADIUS adds two attributes, EAP-Message and Message-Authenticator, for supporting EAP
authentication. For the RADIUS packet format, see "
754H
Configuring AAA ."
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EAP-Message
RADIUS encapsulates EAP packets in the EAP-Message attribute, as shown in
755H
Figure 25 . The Type field
takes 79, and the Value field can be up to 253 bytes. If an EAP packet is longer than 253 bytes, RADIUS
encapsulates it in multiple EAP-Message attributes.
Figure 25 EAP-Message attribute format
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Message-Authenticator
RADIUS includes the Message-Authenticator attribute in all packets that have an EAP-Message attribute
to check their integrity. The packet receiver drops the packet if the calculated packet integrity checksum
is different from the Message-Authenticator attribute value. The Message-Authenticator prevents EAP
authentication packets from being tampered with during EAP authentication.
Figure 26 Message-Authenticator attribute format
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Initiating 802.1X authentication
Both the 802.1X client and the access device can initiate 802.1X authentication.
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802.1X client as the initiator
The client sends an EAPOL-Start packet to the access device to initiate 802.1X authentication. The
destination MAC address of the packet is the IEEE 802.1X specified multicast address
01-80-C2-00-00-03 or the broadcast MAC address. If any intermediate device between the client and