Dell Force10 S55T S55 Configuration Guide FTOS 8.3.5.3 - Page 369

19 Link Aggregation Control Protoco c e s Link Aggregation Control Protoco is supported on platforms The major sections in the chapter are: • Introduction to Dynamic LAGs and LACP on page 369 • LACP Configuration Tasks on page 371 • Shared LAG State Tracking on page 374 • Configure LACP as Hitless on page 376 • LACP Basic Configuration Example on page 377 Introduction to Dynamic LAGs and LACP A Link Aggregation Group (LAG), referred to as a port channel by FTOS, can provide both load-sharing and port redundancy across line cards. LAGs can be enabled as static or dynamic. The benefits and constraints are basically the same, as described in Port Channel Interfaces on page 294 in Chapter 15, Interfaces. The unique benefit of a dynamic LAG is that its ports can toggle between participating in the LAG or acting as dedicated ports, whereas ports in a static LAG must be specifically removed from the LAG in order to act alone. FTOS uses LACP to create dynamic LAGs. LACP provides a standardized means of exchanging information between two systems (also called Partner Systems) and automatically establishes the LAG between the systems. LACP permits the exchange of messages on a link to allow their LACP instances to: • Reach agreement on the identity of the LAG to which the link belongs. • Move the link to that LAG. • Enable the transmission and reception functions in an orderly manner. The FTOS implementation of LACP is based on the standards specified in the IEEE 802.3: "Carrier sense multiple access with collision detection (CSMA/CD) access method and physical layer specifications." LACP functions by constantly exchanging custom MAC PDUs across LAN Ethernet links. The protocol packets are only exchanged between ports that are configured as LACP capable. Link Aggregation Control Protoco | 369