Hi,
In traditional interconnection networking, switches are interconnected through GE or 10GE interfaces. Through the continuous growth of the business, this method of device interconnection will have great limitations:
Potential service interruption: The device may be out of managed from the network due to the interruption of the only interconnection, causing the service carried by the connected device to be interrupted;
Link congestion: The growth of a large number of services has caused insufficient interconnection bandwidth, resulting in a large number of packet dropping, and serious response to user experience;
The equipment is replaced too quickly, and the use cost is huge: The investment in the replacement of equipment and hardware equipment has soared in order to adapt to the large increase in business;
Partial problems can be solved by increasing the number of interconnections, and STP blocks the potential network loop, but it is not a long-term solution in the end.
Figure 1: Due to the STP blocking mechanism multi links cannot increase the interconnection bandwidth either
Ethernet link aggregation, also called Eth-Trunk, bundles multiple physical links into a logical link to increase link bandwidth. The bundled links back up each other, increasing reliability.
Figure 2: Link aggregation can effectively use all links
Advantages of link aggregation:
Increased bandwidth: The bandwidth of the link aggregation interface is the sum of the bandwidth of member interfaces.
Higher reliability: When an active link fails, traffic on this active link moves to another active link, improving the reliability of the link aggregation interface.
Load balancing: In a link aggregation group (LAG), traffic is load-balanced among active link members.
To establish link aggregation, we have two methods: manual link aggregation and LACP mode link aggregation.
Manual link aggregation
The Eth-trunk creating and adding member links should be performed by the administrator manually. In this mode, LACP is not required. When the aggregated link is operating normally, all links are active links and participate in data forwarding. If one active link fails, traffic is load-balanced among the remaining active links.
For the manual mode link aggregation, it is easy to do the configuration, on the contrary, manual mode cannot detect the link disconnections.
LACP mode link aggregation:
LACP provides a standard negotiation mechanism for a switching device so that the switching device can automatically form and start the aggregated link according to its configuration. LACP is responsible for maintaining the link status after the aggregated link is formed and adjusting or removing the aggregated link when the link aggregation condition is changed. When the aggregated link is operating normally, only some links are active links. All active links participate in data forwarding. If an active link fails, the system selects one of the inactive links to be the active link, ensuring the number of links participating in data forwarding remains unchanged.
Similarly, the LACP mode also has disadvantages, that is, the LACP protocol consumes a certain amount of link bandwidth.
This is all of this chapter. We will introduce manual link aggregation and LACP mode link aggregation in detail for you in the following chapters, and present you with related configurations and result checks.
