Quanta Cloud Technology QuantaMesh QNOS5, Configuration Manual

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QNOS software support configuration of hashing algorithms for each Port-channel interface. The hashing
algorithm is used to distribute traffic load among the physical ports of the Port-channel while preserving the
per-flow packet order.
The hashing algorithm uses various packet attributes to determine the outgoing physical port. The switch
supports the following set of packet attributes to be used for hash computation:

Source MAC, VLAN, EtherType, and incoming port.

Destination MAC, VLAN, EtherType, and incoming port.

Source IP and Source TCP/UDP port numbers.

Destination IP and Destination TCP/UDP port numbers.

Source/Destination MAC, VLAN, EtherType, and incoming port.

Source/Destination IP and Source/Destination TCP/UDP port numbers.

Enhanced hashing mode
Enhanced hashing mode has following advantages:

MODULO-N operation based on the number of ports in the Port-channel.

Packet attributes selection based on the packet type. For L2 packets, Source and Destination
MAC address are used for hash computation. For IP packets, Source IP, Destination IP address,
TCP/UDP ports are used.

Non-Unicast traffic and Unicast traffic is hashed using a common hash algorithm.

Excellent load balancing performance.
3.3.2.1. Resilient Hasing
Resilient Hashing (RH) is a feature on QNOS switches that introduces an extra level of indirection between
the hash value and the selected output port for a layer-2 Port-channel or a layer-3 ECMP route. In a typical
non-RH configuration, the output port can change for all flows when the number of ports changes, even if
the flow was on a port that was not affected. This can cause degraded performance due to frame reordering.
With RH, the hash value is used to index into a table of ports. If a port goes down, then only the entries that
use that port are rewritten. Other ports are left untouched and, therefore, do not suffer degraded
performance.
Resilient hashing is globally enabled on switch ports by default. It can be globally enabled (or disabled) in
Global Config mode using the
(no) port-channel resilient-hashing command for Port-channels or the (no) ip
resilient-hashing command for ECMP routes. The new setting takes effect after a system reboot.
3.3.2.2. Hash Prediction with ECMP and Port-channel
The Hash Prediction feature provides a utility to predict how packets will be forwarded over a Port-channel or
to the next- hop device when Equal-Cost Multipath (ECMP) is the destination. Given the Port-channel
method, ingress physical port, and values of various packet fields, the utility predicts an egress physical port
for the packet.