A54-3002-027
• Rev B
13
APCON, Inc.
Bypass Switch TAP/Aggregator User Manual
Chapter 2 Introduction
The failback action for the Bypass TAP occurs within 10 seconds of detecting the absence of
heartbeat packets returning from the module or loss of Link.
♦
Heartbeat operation
To determine when the Bypass TAP switches into Bypass mode, the blade inserts heartbeat
packets into the network traffic going to the network tool from both directions. These packets
are generated internally and inserted into the data stream.
The blade monitors the returning network traffic from the tool for the heartbeat packets.
If a user-specified number of packets fail to return within a specified interval, the blade
assumes a failover Condition has occurred and switches from Monitor to Bypass mode.
In the above diagram, network traffic entering the blade from Network ports (A1N1 and A1N2)
have heartbeat packets inserted into the data streams. If the user-specified number of
heartbeat packets do not return from either direction in the specified interval, the blade
assumes a failover Condition has occurred and switches from Monitor to Bypass mode, thus
bypassing the network tool.
♦
Load-Balanced Group Configuration
In a Load Balanced Group (LBG) configuration, a network outage would result in all of the
traffic bypassing the Bypass TAP, just as occurs in a non-LBG configuration. The advantage in
an LBG configuration is that if a loss of an in-line monitoring tool occurs, traffic destined for
NOTE
When no power is applied to the Bypass TAP, the blade is in Bypass mode.
Therefore, if the blade loses power, it switches to Bypass mode so the user does
not lose network traffic.
