Control Packet Format; Table 3: Bfd Control Packet Field Descriptions; Figure 8: Mandatory Frame Format - Alcatel-Lucent 7750 SR OS Configuration Manual

Configuring IP Router Parameters
If multiple BFD sessions exist between two nodes, the BFD discriminator is used to de-multiplex
the BFD control packet to the appropriate BFD session.

Control Packet Format

The BFD control packet has 2 sections, a mandatory section and an optional authentication section.
0
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Vers |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Table 3: BFD Control Packet Field Descriptions

Field
Vers
Diag
H Bit
Page 34
1
Diag |Sta|P|F|C|A|D|R|
My Discriminator
Your Discriminator
Desired Min TX Interval
Required Min RX Interval
Required Min Echo RX Interval

Figure 8: Mandatory Frame Format

The version number of the protocol. The initial protocol version is 0.
A diagnostic code specifying the local system's reason for the last transition of the
session from Up to some other state.
Possible values are:
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
The "I Hear You" bit. This bit is set to 0 if the transmitting system either is not
receiving BFD packets from the remote system, or is in the process of tearing down
the BFD session for some reason. Otherwise, during normal operation, it is set to 1.
7750 SR OS Router Configuration Guide
2
Detect Mult | Length
Description
3
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