F3726, F3211, F3174, R5135, R3816-HP Firewalls and UTM Devices High Availability Configuration Guide-6PW100

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• Simple—Simple authentication.
• MD5—MD5 (Message Digest 5) authentication.
• SHA1—SHA1 (Secure Hash Algorithm 1) authentication.
216BBFD packet format
BFD control packets are encapsulated into UDP packets with port number 3784 for single-hop detection
or port number 4784 for multi-hop detection (also can be 3784 based on the configuration task). BFD
echo packets have a similar format as BFD control packets with UDP port number 3785 except that the
Desired Min TX Interval and Required Min RX Interval fields are null.
664HFigure 147 illustrates the packet
format.
Figure 147 BFD packet format
• Vers—Protocol version. The protocol version is 1.
• Diag—This bit indicates the reason for the last transition of the local session from up to some other
state.
665HTable 27 lists the states.
Table 27 Diag bit values
Dia
g
Descri
p
tion
0 No Diagnostic.
1 Control Detection Time Expired.
2 Echo Function Failed.
3 Neighbor Signaled Session Down.
4 Forwarding Plane Reset.
5 Path Down.
6 Concatenated Path Down.
7 Administratively Down.
8 Reverse Concatenated Path Down.
9–31 Reserved for future use.
• State (Sta)—Current BFD session state. Its value can be 0 for AdminDown, 1 for Down, 2 for Init,
and 3 for Up.
• Poll (P)—If set, the transmitting system is requesting verification of connectivity, or of a parameter
change. If clear, the transmitting system is not requesting verification.