Link Aggregation; Chapter 17 Link Aggregation; Link Aggregation Overview; Dynamic Link Aggregation - ZyXEL Communications XS3800-28 User Manual

This chapter shows you how to logically aggregate physical links to form one logical, higher-bandwidth
link.

17.1 Link Aggregation Overview

Link aggregation (trunking) is the grouping of physical ports into one logical higher-capacity link. You
may want to trunk ports if for example, it is cheaper to use multiple lower-speed links than to under-utilize
a high-speed, but more costly, single-port link.
However, the more ports you aggregate then the fewer available ports you have. A trunk group is one
logical link containing multiple ports.
The beginning port of each trunk group must be physically connected to form a trunk group.
The Switch supports both static and dynamic link aggregation.
Note: In a properly planned network, it is recommended to implement static link aggregation
only. This ensures increased network stability and control over the trunk groups on your
Switch.
See Section 17.6 on page 204

17.2 Dynamic Link Aggregation

The Switch adheres to the IEEE 802.3ad standard for static and dynamic (LACP) port trunking.
The Switch supports the link aggregation IEEE802.3ad standard. This standard describes the Link
Aggregation Control Protocol (LACP), which is a protocol that dynamically creates and manages trunk
groups.
When you enable LACP link aggregation on a port, the port can automatically negotiate with the ports
at the remote end of a link to establish trunk groups. LACP also allows port redundancy, that is, if an
operational port fails, then one of the "standby" ports become operational without user intervention.
Please note that:
• You must connect all ports point-to-point to the same Ethernet switch and configure the ports for
LACP trunking.
• LACP only works on full-duplex links.
• All ports in the same trunk group must have the same media type, speed, duplex mode and flow
control settings.

Link Aggregation

for a static port trunking example.
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