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As I understand it, a "Bonded NIC" has two purposes:

  1. Redundancy in the event of a NIC failure
  2. Additional bandwidth

The former would only protect against an internet connection failure in the event that:

  1. More than one ISPs connection did not fail.
  2. The switches that the bonded NIC connect to did not fail.
  3. All of the server's local NICs included in the bonded NIC did not fail.

As far as providing additional bandwidth to the server (for instance, during a large backup), you could have it connected two different ways, with more than one internet connection, or just a single internet connection.

In the case that there are two internet connections it seems to go without saying that the server would receive more bandwidth, but in the case that both bonded NICs only have one route to follow (though a single internet connection, or only inside the same LAN), does the server still have more bandwidth to use, or is it limited by the maximum amount of bandwidth on the network?

leeand00
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1 Answers1

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Bonded nic works at layer 2 level. There are different type of bonding. Some requires a switch that collaborates with the other end, like LACP. Other do not require any switch configuration (failover, ...).

Therefore bonding provides indeed redundancy, but only up to your switch. It will not provide redundancy at layer 3 (routing). The additional bandwidth is only up to the switch (or connected device).

Redundancy at internet level requires multihoming. So, in your assumption, point 1 (More than one ISPs connection did not fail) is wrong.

The bonded nic are effective, but has nothing to do with internet connection.

Bruno Mairlot
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