Lacp Multiplexing - Alcatel-Lucent 7750 Configuration Manual

Interface Configuration

LACP Multiplexing

The 7750 SR supports two modes of multiplexing RX/TX control for LACP: coupled and
independent.
In coupled mode (default), both RX and TX are enabled or disabled at the same time whenever a
port is added or removed from a LAG group.
In independent mode, RX is first enabled when a link state is UP. LACP sends an indication to the
far-end that it is ready to receive traffic. Upon the reception of this indication, the far-end system
can enable TX. Therefore, in independent RX/TX control, LACP adds a link into a LAG only
when it detects that the other end is ready to receive traffic. This minimizes traffic loss that might
occur in coupled mode if a port is added into a LAG before notifying the far-end system or before
the far-end system is ready to receive traffic. Similarly, on link removals from LAG, LACP turns
off the distributing and collecting bit and informs the far-end about the state change. This allows
the far-end side to stop sending traffic as soon as possible.
Independent control provides for lossless operation for unicast traffic in most scenarios when
adding new members to a LAG or when removing members from a LAG. It also reduces loss for
multicast and broadcast traffic. When adding a port to LAG in a high scaled deployment, and that
port is the first to be added to the LAG on that forwarding complex, it is recommended to first shut
down the port, add the port to the LAG, and then re-enable the port after a short delay to allow for
forwarding to be reprogrammed. This procedure minimizes outages.
Note that independent and coupled mode are interoperable (i.e. connected systems can have either
mode set).
7750 SR Interface Configuration Guide Page 111