Hello everyone,
This post describes the concept of IEEE 802.3ad and the differences between IEEE 802.3ad and EtherChannel.
What is IEEE 802.3ad?
IEEE 802.3ad is a standard method for performing link aggregation. Conceptually, gathering multiple Ethernet adapters into a single virtual adapter has the same function as "EtherChannel" and can provide higher bandwidth to prevent failure. For example, ent0 and ent1 can be aggregated into an IEEE 802.3ad link aggregation called ent3; then interface en3 is configured with an IP address. The system considers these aggregated adapters as one adapter. Therefore, their IP can be configured like on any Ethernet adapter.
IEEE 802.3ad VS Ethernet channel
Like "Ethernet Channel", IEEE 802.3ad also needs the support of a switch. However, unlike "Ethernet Channel", the switch does not need to be manually configured to understand which ports belong to the same aggregation.
The advantage of using IEEE 802.3ad "Link Aggregation" instead of "Ether Channel" is that it automatically creates link aggregation in the switch, and it allows you to use a switch that supports the IEEE 802.3ad standard but does not support "Ether Channel".
In IEEE 802.3ad, "Link Aggregation Control Protocol" (LACP) automatically informs the switch which ports should be aggregated. After IEEE 802.3ad aggregation is configured, the Link Aggregation Control Protocol Data Unit (LACPDU) will be exchanged between the server and the switch. LACP will notify the switch that the adapter configured in the aggregation should be considered as an adapter on the switch without user intervention.
Although the IEEE 802.3ad specification does not allow users to choose which adapters to aggregate, the AIX implementation allows users to choose adapters. According to the rules of the protocol, LACP completely decides which adapters should be grouped together (by using similar link speeds and dual settings to make a link aggregation of all the adapters). This prevents you from deciding which adapters should be used stand-alone and which adapters should be clustered together. However, AIX implements control over how the adapter is used, and it never creates links arbitrarily. This is very important for managing adapters.
To be able to aggregate adapters (that is, the switch will allow them to belong to the same aggregation), their line speeds must be the same (for example, all 100 Mbps or 1 Gbps), and they must all be full-duplex. If you try to group together adapters with different line speeds or different full-duplex modes, you can successfully create an aggregation on AIX, but the switch may not group these adapters together. If the switch does not successfully cluster the adapters together, you may notice a decrease in network performance.
According to the IEEE 802.3ad specification, data packets destined for the same IP address will all be sent through the same adapter. Therefore, when operating in 8023ad mode, the information package will always be distributed according to the standard (Standard) mode, but not according to the round-robin mode.
The backup adapter function is available for IEEE 802.3ad "Link Aggregation", just like "Ether Channel". The backup adapter does not need to be connected to an IEEE 802.3ad-enabled switch, but if it is already connected, the backup adapter will still comply with IEEE 802.3ad LACP.
If the switch supports "Ether Channel" but not IEEE 802.3ad, you can also configure "IEEE 802.3ad Link Aggregation". In that case, you must manually configure the port as an "Ether Channel" on the switch (just like a regular "Ether Channel" has been created). After the mode is set to 8023ad, the aggregation will work with switches that have "Ether Channel" enabled and IEEE 802.3ad enabled.
That is all I want to share with you!
