Tripp Lite NGI-M05-C1, Руководство пользователя, Страница: 121 / 254

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6.6. Dual Homing
Dual Homing, a network topology in which a device is connected to the network by the
way of two independent access points (points of attachment). One access point is
considered as a primary connection while other is standby. The standby access point is
getting activated once primary connection fails.
How Dual-Homing Works?
Let us assume that both the primary and secondary connections are connected to
Internet by means of different ways. For example, primary connection is connected to a
physical network whereas the secondary one is attached to a wireless network. When
dual homing feature is enabling, by default through primary connection the device will
get connect to Internet at the same time the secondary connection will be shutdown. If
the port or all the ports of primary connection are link-down then the device will
replace its primary connection by the secondary one to connect with the Internet. If in
any situation the secondary connection also link-down, device will do nothing.
Secondary connection only works when primary connection is getting disconnect.
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Dual Homing LPT Mode vs. Dual Homing :
The following figure is represented a ring connectivity between Switch-1, Switch-2 and
Switch-3. In the discussed scenario, the Dual Homing LPT mode is enabled in the Switch-
2 and Dual Homing is enabled in the Switch-3. Based on the mechanism of Dual Homing,
the Secondary port of the Switch-3 will be shutdown which ensures a loop free ring
connectivity.
Consider the scenario, if the source port between the Switch-2 and Switch-1 is link down,
then the Destination port will automatically shutdown by the Dual Homing LPT mode.
When the Switch-3 detects the Primary port gets link down, it will enable its Secondary
port for continuing the communication. As a result, the hosts connected to the Switch-3
still can communicate with the hosts of Switch-1 without any interruption.