Configuring LAG Hash

LAG-Hash is used to describe the load-balancing algorithm used for distributing traffic across the links within a port channel. This algorithm plays a crucial role in determining the distribution of traffic evenly among the member links of the port channel.

APB uses the CRC2 for NVIDIA ASIC and CRC32_LO for Broadcom ASIC for load-balancing traffic across a port channel.

Reference

Command	lag-hash seed <int seed_value>
Description	seed value 0 - 4294967295
Parameters	integer seed value
Mode	CONFIG

pbnoscli# configure terminal 
pbnoscli(config)# lag-hash 
  seed                  seed configuration
pbnoscli(config)# lag-hash seed 
  <seed_val>            seed value 0..4294967295
pbnoscli(config)# lag-hash seed 429496723
pbnoscli(config)# 

You can verify the configuration by using the command(s) below:

pbnoscli# show lag-hash config 
===================================================
LAG Hash Parameters
===================================================
Hash Algorithm : CRC2
Symmetric Hash : Enabled
SEED Value     : 429496723
pbnoscli# 

Dynamic LAG Hash settings (NVIDIA)

This feature provides the support to configure the lag hash fields of outer and inner packet fields. This allows the user to choose the Load Balancing methods say only Inner 5-tuple / Inner 3-Tuple / Outer+Inner 5 Tuple.

Hash Fields

• L2: Source MAC, Destination Mac

• IPv4: Source IP, Destination IP, Protocol, L4 Source Port, L4 Destination Port

• IPv6: Source IP, Destination IP, Next Header

This is a global configuration command which applies hash fields to all existing ethernet, port-channel and breakout interfaces.

pbnoscli# configure terminal
pbnoscli(config)# lag-hash fields [outer-mac] [outer-ip] [outer-port] [outer-proto] [inner-mac] [inner-ip] [inner-port] [inner-proto]
pbnoscli(config)# no lag-hash fields 
pbnoscli# show lag-hash config
<Configured params>

• Existing traffic will be modified according to the updated hash fields.

• The system shall automatically update the existing LAG hash fields when new breakout interfaces are created

Remove LAG hash fields before creating a port-channel and reapply them afterward Hash field configurations must be restored and applied correctly after save and reboot.