Figure 28-1. LAG Configuration
Wiring Closet Switch
Data Center Switch
LAGs can be configured on stand-alone or stacked switches. In a stack of
switches, the LAG can consist of ports on a single unit or across multiple
stack members. When a LAG members span different units across a stack,
and a unit fails, the remaining LAG members on the functional units
continue to handle traffic for the LAG.
Why Are Link Aggregation Groups Necessary?
The primary purpose of LAGs is to increase the overall bandwidth between
two switches. This is accomplished by effectively aggregating multiple ports
together that act as a single, logical connection between the two switches.
LAGs also provide redundancy. If a link fails, traffic is automatically
redistributed across the remaining links.
What Is the Difference Between Static and Dynamic Link Aggregation?
Link aggregation can be configured as either dynamic or static. Dynamic
configuration is supported using the IEEE 802.3ad standard, which is known
as Link Aggregation Control Protocol (LACP). Static configuration is used
when connecting a PowerConnect M6220/M6348/M8024/M8024-k switch to
an external Gigabit Ethernet switch that does not support LACP.
One advantage of LACP is that the protocol enables the switch to confirm
that the external switch is also configured for link aggregation. When using
static configuration, a cabling or configuration mistake involving the M6220,
M6348, M8024, and M8024-k switch or the external switch could go
undetected and thus cause undesirable network behavior. Both static and
dynamic LAGs (via LACP) can detect physical link failures within the LAG
and continue forwarding traffic through the other connected links within that
same LAG. LACP can also detect switch or port failures that do not result in
Configuring Link Aggregation