Dell PowerConnect 7048P User Manual - Page 820

Figure 28-1. LAG Configuration Wiring Closet Switch LAG 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 7000 Series 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 7000 Series 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 loss of link. This provides a 820 Configuring Link Aggregation