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Link Aggregation Control Protocol or LACP is one element of an IEEE specification (802.3ad) that provides guidance on the practice of link aggregation for data connections.
Importantly, LACP typically applies to strategies that bundle individual links of Ethernet connections, and not wireless transfers.
To understand Link Aggregation Control Protocol, it's important to first know what link aggregation is and what it means for networks.
Link aggregation is the practice of bundling individual links on a network to promote better performance outcomes.
The semantics here can vary: insiders might talk about similar practices like port trunking or link bundling in ways that can cloud the particular definition: again, LACP is built on specific protocol revealed in IEEE 802.3ad and elsewhere.
Experts may refer to groups of ports as “link aggregation groups” or label the parts and pieces, including physical ports, in more nuanced ways, which might require some clarification.
First, it provides redundant network activity. Suppose you have a single link, and that link fails. All of a sudden, you have a 100% lack of data connectivity. Your system just cuts off, it “goes dark.”
With link aggregation, on the other hand, you get multiple delivery paths, and the ability to do load-balancing across all of the available links. Now, using the same link for each related packet is still a best practice.
Making sure that all related data packets go through the same individual link solves potential problems with out-of-order packets, and link aggregation has to address this reality.
However, as you might imagine, the bundling of individual links leads to much more durable signal interfaces.
There's also the promise of “graceful degradation” — in other words, failure occurs slowly, and gradually, not all at once.
Instead of “cutting off,” a signal might only initially suffer a small but of degradation, giving the end user or other stakeholders time to react and diagnose the problem and address it.
Various link aggregation configuration guidelines help to optimize how link aggregation protects network data and performance.
With that in mind, LACP promotes the formation of better logical virtual links or bundles that can be handled as one unified whole by an MAC client.
Generally, the bundling offers system designers and administrators new ways of addressing points of failure and recovery capabilities without going to greater extremes.
As part of Link Aggregation Control Protocol practices, engineers identify the aggregated interface, and confirm link status. The identifier value for the virtual local area network will also be included.
As noted by experts, it's important that devices on both ends of the connection support link aggregation in the same ways, so “termination” may also be important.
Systems inherent in the LACP process can also help to handle the out-of-order packet problem: tools referred to as “scheduling algorithms” define packet-to-packet activity to keep things working well.
Although vendor systems provide for this protocol, some open source providers also accommodate the implementation of link aggregation with resources to help support this type of approach.
In general, LACP helps to standardize how link aggregation happens, for more durable Ethernet transmissions.