Configurable Hash Weight to Control Flow Distribution

The operator can use the LAG port hash-weight to further control the flow distribution between LAG ports.

This capability can be especially useful when LAG links on Nokia routers are rate limited by a 3rd party operator providing the connectivity between two sites as shown in the Figure 1:

LAG links 1/1/1 and 1/1/2 are GE
LAG link 1/1/1 is rate limited to 300 Mpbs by a 3rd party transport operator
LAG Link 1/1/2 is rate limited to 500 Mpbs by a 3rd party transport operator

Figure 1. Same Speed LAG with Ports of Different hash-weight

In this context, the operator can configure the LAG to adapt the flow distribution between LAG ports according to the bandwidth restrictions on each port using customized hash-weight values as shown in the following configuration example:

A:Dut-A>config>lag# info
----------------------------------------------
        port 1/1/1 hash-weight 300
        port 1/1/2 hash-weight 500
        no shutdown
----------------------------------------------

The operator can also display the resulting flow-distribution between active LAG ports using the following show command:

A:Dut-A# show lag 3 flow-distribution
===============================================================================
Distribution of allocated flows
===============================================================================
Port                        Bandwidth (Gbps) Hash-weight  Flow-share (%)
-------------------------------------------------------------------------------
1/1/1                       10.000           300          37.50
1/1/2                       10.000           500          62.50
-------------------------------------------------------------------------------
Total operational bandwidth: 20.000
===============================================================================

Note:

hash-weight and same-speed LAG:

If all ports have a hash-weight configured other than port-speed, then the configured value is used and normalized to modify the hashing between LAG ports.
If the LAG ports are all configured to port-speed, or if only some of the ports have a customized hash-weight value, then the system uses a hash weight of 1 for every port in case of same-speed LAG. For mixed-speed LAG, the system uses the port-speed value.