Bind dual NICs in Linux for load balancing and failure protection

In this article, the implementation of dual-Nic binding in Linux is to use two NICs to virtualize a single NIC. the aggregated device looks like a separate Ethernet interface device. Generally speaking, two NICs are used.

In this article, the dual-Nic binding implementation in Linux is to use two NICs to virtualize a single NIC. the aggregated device looks like a separate Ethernet interface device, in general, two NICs have the same IP address, and parallel links are aggregated into a logical link. In fact, this technology already exists in Sun and Cisco, known as Trunking and Etherchannel technology. it is also used in Linux 2.4.x kernel, known as bonding. The earliest application of bonding technology was on the cluster beowulf, designed to improve data transmission between cluster nodes. Next we will discuss the principles of bonding. what is bonding? it should start with the promisc mode of the NIC. We know that, under normal circumstances, the network adapter only receives the target hardware Address (MAC Address) as its own Mac Ethernet frame, and filters out all other data frames to reduce the burden on the driver. However, the NIC also supports another mode called hybrid promisc, which can receive all frames on the network. for example, tcpdump runs in this mode. Bonding also runs in this mode, and modifies the mac address in the driver, changing the Mac address of the two NICs to the same, can receive data frames of a specific mac. Then, the data frame is sent to the bond driver for processing.

In fact, in linux, it is very simple to bind a dual network card to a single network card. you only need a few steps to complete the configuration. let's try it together. First of all, let's give a brief introduction to the experiment environment:

Operating system: RedHat Enterprise linux 4.0

Prerequisites: the chipset model is the same, and the NIC should have its own independent BIOS chip.