Lacp With No Link Partner - Cisco 220 Series Smart Plus Administration Manual

Port Management
Configuring Link Aggregation
Cisco 220 Series Smart Plus Switches Administration Guide Release 1.0.0.x
A dynamic LAG can have up to 16 Ethernet ports of the same type. Up to eight
ports can be active, and up to eight ports can be in standby mode. When there are
more than eight ports in the dynamic LAG, the switch on the controlling end of the
link uses port priorities to determine which ports are bundled into the LAG and
which ports are put in hot-standby mode. Port priorities on the other device (the
non-controlling end of the link) are ignored.
The additional rules are additional rules used to select the active or standby ports
in a dynamic LACP:
• Any link operating at a different speed from the highest-speed active
member or operating at half-duplex is made standby. All the active ports in
a dynamic LAG operate at the same baud rate.
• If the port LACP priority of the link is lower than that of the currently-active
link members, and the number of active members is already at the
maximum number, the link is made inactive, and placed in standby mode.

LACP With No Link Partner

LACP With No Link Partner
In order for LACP to create a LAG, the ports on both link ends should be
configured for LACP, meaning that the ports send LACP PDUs and handle received
PDUs.
However, there are cases when one link partner is temporarily not configured for
LACP. One example for such case is when the link partner is on a device, which is
in the process of receiving its configuration using the auto-config protocol. This
device's ports are not yet configured to LACP. If the LAG link cannot come up, the
device cannot ever become configured. A similar case occurs with dual-NIC
network-boot computers (e.g. PXE), which receive their LAG configuration only
after they bootup.
When several LACP-configured ports are configured, and the link comes up in one
or more ports but there are no LACP responses from the link partner for those
ports, the first port that had link up is added to the LACP LAG and becomes active
(the other ports become non-candidates). In this way, the neighbor device can, for
example, get its IP Address using DHCP and get its configuration using
autoconfiguration.
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