TCP/IP Tutorial and Technical Overview - IBM Redbooks

Figure 23-21 shows the sniffer trace for an EAPoL-Logoff packet.
Figure 23-21 EAPoL-Logoff packet
Figure 23-22 shows the EAPOL-Key packet format. The Packet type field in the
802.1x header has the value of 3 to indicate that it is an EAPOL-Key packet.
6 6 2 1 1 2 1 2 8 16 1 16
(Bytes)
N(Bytes)
Destination
address
Source
address
Ethernet Header
Type
0x888E
Protocol
version
1
Figure 23-22 EAPoL-Key packet format
Figure 23-23 shows the sniffer trace for an EAPoL-Key packet.
Figure 23-23 EAPoL-Key packet
23.3.1 Port based network access control functional considerations
The standard for port based network access control allows for the flexibility in
deployment. Any device capable of supporting 802.1x can act as any
combination of a supplicant, authenticator, and authentication server. However,
to leverage the greatest amount of functionality, the IEEE 802.1x standard
suggests the use of the following aspects.
904 TCP/IP Tutorial and Technical Overview
Packet
type
3
802.1x/EAPOL Header
Packet
body length Descriptor
type
key
lengt
h
Replay
counter
Key
IV
Key descriptor
Key
index
Key
signature
Key