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Chapter 6 IP security and VPN
300868-G
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Monitor Mode – The monitor mode does not initiate a connection and is not
considered to be activity against a dial-up interface’s idle timeout. This mode
does not keep a connection active.
In monitor mode, if the specified interface is not active the ping does not
occur. Also, in the case of an IPsec interface, if the interface used to reach the
corresponding remote gateway is not active, then the ping does not occur. If
an IPsec interface is specified and no response is received for three
consecutive pings, the tunnel information is destroyed and is rebuilt as
required by normal VPN activity.
If the ping fails for three consecutive times, the interface is brought down, but
is not disabled from further activity. This is normally used for IPsec interfaces
because the ping failure indicates that the IPsec tunnel is no longer operating
properly. If this happens, any active IPsec tunnels are destroyed and are
rebuilt as required by normal activity.
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Control Mode – The control mode is useful for maintaining permanent
connections, switching to a backup interface when a primary interface
becomes unavailable and the primary interface does not have a reliable
indication of its availability or both.
For example, in xDSL and cable modem environments, the Instant Internet
interface that connects to the Internet is usually an Ethernet interface, and that
interface is always active as long as the link exists between Instant Internet
and the xDSL or cable modem. A ping in control mode always attempts to use
the specified interface (even if it is considered inactive for normal use), and if
three consecutive responses are not received, the interface is made inactive (if
an IPsec interface is used, any associated tunnels are destroyed). The ping
continues to transmit on the interface, even while it is unavailable for normal
traffic. After responses are received, the interface is made available again.
Note:
A monitor ping is considered to be activity on the CES but is not
considered to be activity against Instant Internet’s dial-up timeout.
Therefore, Instant Internet is free to drop the line. After the line is
dropped, the monitor ping disables the connection. The CES idle timeout
disables the other end of the connection.
Note:
The control mode initiates a connection and is considered as
activity. A control mode ping attempts to keep the path to the destination
active at all times.
Содержание 400
Страница 16: ...16 Contents 300868 G ...
Страница 22: ...22 Figures 300868 G ...
Страница 24: ...24 Tables 300868 G ...
Страница 92: ...92 Chapter 2 User access administration 300868 G ...
Страница 114: ...114 Chapter 3 Internet activity logging 300868 G ...
Страница 166: ...166 Chapter 5 Advanced IP configuration 300868 G ...
Страница 200: ...200 Chapter 6 IP security and VPN 300868 G ...
Страница 256: ...256 Chapter 8 Advanced communications configuration 300868 G ...
Страница 302: ...302 Chapter 10 Instant Internet unit configuration support and diagnostics 300868 G ...
Страница 314: ...314 Appendix A Troubleshooting and error messages 300868 G ...
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