Rather than distribute to all active members in a LAG (Link Aggregation Group), you have two options to specify a subset of the active member ports as eligible for distribution on a per slot basis: “local slot distribution” and “distribution port lists”. The specific choice of configuration is described in the command line syntax as a distribution-mode. The choice of distribution mode is configurable per LAG. You may dynamically switch between distribution modes using the configure sharing distribution-mode command.
The “local-slot” distribution mode restricts distribution of unicast packets to the active LAG members on the same slot where the packet was received. If no active LAG members are present on the slot where the packet was received, all active LAG member ports are included in the distribution algorithm. The “local-slot” distribution mode is useful for reducing the fabric bandwidth load of a switch. Reducing fabric bandwidth may be especially important for a SummitStack, which has significantly less fabric (inter-slot) bandwidth available in comparison to chassis switches. In many SummitStack hardware configurations, the “local-slot” distribution mode may reduce the switching latency of some flows distributed to a LAG.
The “port-lists” distribution mode configures one or more LAG member ports to be eligible for unicast LAG distribution on each slot in a switch. If a slot does not have a distribution port list configured or if none of the configured member ports is active in the LAG, all active member ports are eligible for unicast distribution. The use of the “port-lists” distribution mode should be taken into consideration when adding ports to a LAG with the configure sharing command. Any newly added port on a LAG is not available for unicast distribution unless it is also added to the distribution port list of at least one slot.
The distribution modes affect only the distribution of known unicast packets on a LAG. Non-unicast packets are distributed among all active members of a LAG.
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