Configurable per Slot Link Aggregation Group (LAG) Member Port Distribution

Previously, ExtremeXOS switches would always distribute to all active members in a link aggregation group (LAG). This enhancement provides two options for specifying 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.

Local Slot Distribution

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 chassis or SummitStack hardware configurations, the “local-slot” distribution mode may reduce the switching latency of some flows distributed to a LAG.

Distribution Port Lists

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.

Supported Platforms

  • Summit X430, X440, X450-G2, X460, X460-G2, X480, X670, X670-G2, X770 series switches in stacks
  • BlackDiamond X8 and 8000 series switches


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.

Changed CLI Commands

Changes are underlined.

enable sharing master_port grouping member_port_list {algorithm [address-based {L2 | L3 | L3_L4 | custom} | port-based]} {distribution-mode [all | local-slot | portlists]} {lacp | health-check}

configure sharing master_port distribution-mode [all| local-slot | port-lists]

configure sharing master_port slot slot distributionlist [port_list | add port_list | delete [port_list] | all]]

The show sharing and show ports port_list sharing commands now display the distribution mode for a LAG under the “Flag” column:

Distribution Mode Flags:

A - All: Distribute to all members

L - Local: Distribute to members local to ingress slot

P - Port Lists: Distribute to per-slot configurable subset of members

The show sharing and show ports port_list sharing commands now display the configured distribution mode and distribution port lists for LAGs:

show {ports port_list} sharing {distribution configuration}

Config Distribution Distribution
Master Mode Lists
1:1 Port Lists Slot 1: 1:1-10, 1:15
Slot 5: 1:11-22
1:25 Local Slot Slot 1: 1:25
Slot 5: 1:26
5:1 Port Lists
5:10 All Slot 1: 5:11
Slot 5: 5:10