TCP/IP Tutorial and Technical Overview - IBM Redbooks

esponse, success, and failure packets. The Identifier field matches the
responses with requests. When a response is sent for a particular request, the
value of the Identifier field in the response packet is the same as that of the
request. The Length field indicates the length of the EAP packet, which includes
only an EAP header and data field.
(Bytes)
Destination
address
6 6 2 1 1 2 1 1 2 N (Bytes)
Source
address
Type
0x888E
Protocol
version
1
Figure 23-9 EAP packet format
Packet
type
0
EAP-Request and EAP-Response packets
In the EAP header (Figure 23-10), the Code field indicates the type of EAP
packet. A value of 1 indicates that it is an EAP-Request packet. A value of 2
indicates that it is an EAP-Response packet. An additional Type field is present
in the EAP header of the request or response packet. This indicates the type of
request or response packet.
Figure 23-10 EAP-Request and EAP-Response packet format
Table 23-1 provides some major request or response types and their values. The
first three are special types and the remaining types define various
authentication methods.
Table 23-1 Major request and response types
Request and response type Value
Identity 1
Notification 2
Nak (response only) 3
MD-5 challenge 4
One-time password (OTP) 5
Generic token card (GTC) 6
Packet body
length
Ethernet Header 802.1x/EAPOL Header EAP Header
Code Identifier Length Data
(Bytes) 6 6 2 1 1 2 1 1 2
Destination
address
Source
address
Type
0x888E
Protocol
version
1
Packet
type
0
Packet
body length Code Identifier Length Type Data
Ethernet Header 802.1x/EAPOL Header EAP Header
Chapter 23. Port based network access control 899
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N (Bytes)
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