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Bidirectional Forwarding Detection
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handshake. At this point, the discriminator values have been exchanged, and the transmit intervals
have been negotiated.
4. The passive system receives the control packet, changes its state to Up. Both systems agree that a
session has been established. However, since both members must send a control packet—that requires
a response—anytime there is a state change or change in a session parameter, the passive system sends
a final response indicating the state change. After this, periodic control packets are exchanged.
Figure 9-2. BFD Three-way Handshake
Session state changes
Figure 9-3
shows how the session state on a system changes based on the status notification it receives
from the remote system. For example, if a session on a system is down, and it receives a Down status
notification from the remote system, the session state on the local system changes to Init.
ACTIVE System
PASSIVE System
Steady Rate of Control Packets
Version: 1
Diag Code: 0 (assumes no previous session)
State:
Down
Flag:
P:1
Detect Multiplier: User-configurable
My Discriminator:
X
( Active System Session ID)
Your Discriminator:
0
Desired Min TX Interval: User-configurable
Required Min RX Interval: User-configurable
Required Min Echo RX Interval: User-configurable
Init State Change
Version: 1
Diag Code: 0 (assumes no previous session)
State:
Init
Flag:
F: 1
Detect Multiplier: User-configurable
My Discriminator:
Y
(Passsive System Session ID)
Your Discriminator:
X
Desired Min TX Interval: User-configurable
Required Min RX Interval: User-configurable
Required Min Echo RX Interval: User-configurable
Transmit Interval: User-configurable
Up State Change
Version: 1
Diag Code: 0 (assumes no previous session)
State:
Up
Flag:
P: 1
Detect Multiplier: User-configurable
My Discriminator:
X
Your Discriminator:
Y
Desired Min TX Interval: User-configurable
Required Min RX Interval: User-configurable
Required Min Echo RX Interval: User-configurable
Version: 1
Diag Code: 0 (assumes no previous session)
State:
Up
Flag:
F: 1
Detect Multiplier: User-configurable
My Discriminator: Y
Your Discriminator: X
Desired Min TX Interval: User-configurable
Required Min RX Interval: User-configurable
Required Min Echo RX Interval: User-configurable
Up State Change
Default Session State: Down
Default Session State: Down
Periodic Control Packet
Version: 1
Diag Code: 0 (assumes no previous session)
State:
Up
Flag:
P: Clear
Detect Multiplier: User-configurable
My Discriminator: X
Your Discriminator: Y
Desired Min TX Interval: User-configurable
Required Min RX Interval: User-configurable
Required Min Echo RX Interval: User-configurable
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Summary of Contents for Force10 E300
Page 1: ...FTOS Configuration Guide FTOS 8 4 2 7 E Series TeraScale C Series S Series S50 S25 ...
Page 32: ...32 w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 132: ...132 802 1X w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 310: ...310 Configuration Replace and Rollback w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 330: ...330 Dynamic Host Configuration Protocol w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 402: ...402 High Availability w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 462: ...462 Interfaces w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 482: ...482 IPv4 Addressing w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 506: ...506 IPv6 Addressing w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 582: ...582 Layer 2 w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 642: ...642 Multicast Source Discovery Protocol w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 662: ...662 Multiple Spanning Tree Protocol w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 690: ...690 Object Tracking w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 754: ...754 PIM Dense Mode w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 784: ...784 PIM Source Specific Mode w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 800: ...800 Power over Ethernet w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 876: ...876 Quality of Service w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 892: ...892 Routing Information Protocol w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 1006: ...1006 Simple Network Management Protocol w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 1018: ...1018 SONET SDH w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 1048: ...1048 Broadcast Storm Control w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 1096: ...1096 Uplink Failure Detection UFD w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 1098: ...1098 Upgrade Procedures w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 1196: ...1196 C Series Debugging and Diagnostics w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 1252: ...1252 Standards Compliance w w w d e l l c o m s u p p o r t d e l l c o m ...
Page 1262: ...1262 Index w w w d e l l c o m s u p p o r t d e l l c o m ...