Identifies the fields that are used to select ECMP routes and load-sharing group ports.
| L3 | Uses only Layer 3 IP addresses to select ECMP routes and load-sharing ports. |
| L3_L4 | Uses Layer 3 IP addresses and Layer4 TCP/UDP port numbers, if present, to select ECMP routes and load-sharing ports. |
L3_L4.
This command configures the criteria used to select ECMP routes and load-sharing group ports.
For ECMP routes, the configured criteria selects the next hop gateway. The L3 option uses only the source and destination IP addresses to select the next hop gateway. The L3_L4 option uses the Layer4 TCP or UDP port and the source and destination IP addresses to select the next hop gateway.
For load-sharing groups (link aggregation groups), the configured criteria selects the load-sharing group port. The load-sharing groups can be configured to use the following address-based algorithms:
This command affects all the load-sharing groups that use either the L3 or L3_L4 link aggregation algorithm. If the L3 option is specified, all the load-sharing groups that are configured with either the L3 or the L3_L4 address-based link aggregation algorithm use just the Layer 3 IP addresses for the egress port selection. Similarly if the L3_L4 option is specified, all the load-sharing groups that are configured with either L3 or L3_L4 address-based link aggregation algorithm use the Layer 3 IP addresses and Layer4 port number for the egress port selection.
Selecting the L3 option over L3_L4 can be useful in a network where IP fragments are present, since only the first fragment contains the Layer4 TCP or UDP port number. If the L3 option is selected, all IP fragments in a given TCP or UDP session use the same ECMP gateway or load-sharing group port, potentially avoiding inefficient packet reordering by the destination. If IP fragments are not prevalent, better traffic distribution can be achieved by selecting L3_L4.
To display the forwarding sharing feature configuration, enter the command: show forwarding configuration
The following example modifies the sharing selection criteria to use just the Layer 3 IP addresses:
configure forwarding sharing L3
The following example modified the sharing selection criteria to use the Layer 3 and Layer 4 information:
configure forwarding sharing L3_L4
This command was first available in ExtremeXOS 11.6.4.
This command is available only on the BlackDiamond X8 series switches, BlackDiamond 8800 series switch, SummitStack, and the Summit family of switches.
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