Port trunk features and operation

The switches covered in this guide offer these options for port trunking:

LACP: IEEE 802.3ad—Trunk group operation using LACP
Trunk: Non-Protocol—Trunk group operation using the "trunk" option

Up to 60 trunk groups are supported on the switches. The actual maximum depends on the number of ports available on the switch and the number of links in each trunk. (Using the link aggregation control protocol—LACP—option, you can include standby trunked ports in addition to the maximum of eight actively trunking ports.) The trunks do not have to be the same size; For example, 100 two-port trunks and 11 eight-port trunks are supported.


	NOTE: LACP requires full-duplex (FDx) links of the same media type (10/100Base-T, 100FX, and so on) and the same speed, and enforces speed and duplex conformance across a trunk group. For most installations, HP Switch recommends that you leave the port Mode settings at `Auto` (the default). LACP also operates with `Auto-10`, `Auto-100`, and `Auto-1000 (if negotiation selects FDx)`, and `10FDx`, `100FDx`, and `1000FDx` settings. (The 10-gigabit ports available for some switch models allow only the `Auto` setting.)

Fault tolerance

If a link in a port trunk fails, the switch redistributes traffic originally destined for that link to the remaining links in the trunk. The trunk remains operable as long as there is at least one link in operation. If a link is restored, that link is automatically included in the traffic distribution again. The LACP option also offers a standby link capability, which enables you to keep links in reserve for service if one or more of the original active links fails. (See Trunk group operation using LACP.)

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