Alcatel-Lucent 7450 ESS Series, Руководство по настройке

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Page 50 7450 ESS OS Router Configuration Guide
Control Packet Format
The BFD control packet has 2 sections, a mandatory section and an optional authentication section.
0 1 2 3
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 | Diag |Sta|P|F|C|A|D|R| Detect Mult | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| My Discriminator |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Your Discriminator |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Desired Min TX Interval |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Required Min RX Interval |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Required Min Echo RX Interval |
Figure 9: Mandatory Frame Format
Table 4: BFD Control Packet Field Descriptions
Field Description
Vers The version number of the protocol. The initial protocol version is 0.
Diag 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
D Bit The “demand mode” bit. (Not supported)
P Bit The poll bit. If set, the transmitting system is requesting verification of connectiv-
ity, or of a parameter change.
F Bit The final bit. If set, the transmitting system is responding to a received BFD control
packet that had the poll (P) bit set.
Rsvd Reserved bits. These bits must be zero on transmit and ignored on receipt.