H3C LS-3100-52P-OVS-H3 Operation Manual - page 824
1-4
Dynamic BFD parameter changes
After a BFD session is established, both ends can negotiate the related BFD parameters, such as the
minimum transmit interval, minimum receive interval, initialization mode, and packet authentication
mode. After that, both ends use the negotiated parameters, without affecting the current session state.
Authentication modes
BFD provides the following authentication methods:
z
Simple: Plain text authentication
z
MD5: MD5 (Message Digest 5) authentication
z
SHA1: SHA1 (Secure Hash Algorithm 1) authentication
BFD Packet Format
As illustrated in
Figure 1-3
, BFD control packets use UDP and port number 3784.
Figure 1-3 BFD control packet format
z
Vers: Protocol version. The protocol version is 1.
z
Diag: This bit indicates the reason for the last transition of the local protocol from up to some other
state.
Table 1-1
lists the states.
Table 1-1 Diag bit values
Diag
Description
0 No
Diagnostic
1
Control Detection Time Expired
2
Echo Function Failed
3
Neighbor Signaled Session Down
4
Forwarding Pane Reset
5 Path
Down
6
Concatenated Path Down
7 Administratively
Down
8~31
Reserved for future use
z
State (Sta): Current BFD session state. Its value can be 0 for AdminDown, 1 for Down, 2 for Init,
and 3 for Up.