You can use per-packet load sharing to evenly distribute data traffic in an IP network over multiple equal-cost connections.
Per-packet load sharing allows the router to send successive data packets over paths on a packet-by-packet basis rather than
on a per-flow basis.
Using per-packet load sharing can result in out-of-order packets. Packets for a given pair of source-destination hosts might
take different paths and arrive at the destination out of order. Make sure you understand the implications of out-of-order
packets to your network and applications. Per-packet load sharing is not appropriate for all networks. Per-flow load sharing
ensures packets always arrive in the order that they were sent.
Per-packet load sharing uses the round-robin method to determine
which path each packet takes to the destination. With per-packet
load sharing enabled on interfaces, the router sends one packet for
destination1 over the first path, the second packet for (the same)
destination1 over the second path, and so on. Per-packet load
sharing ensures balancing over multiple links.
Use per-packet load sharing to ensure that a path for a single
source-destination pair does not get overloaded. If most of the
traffic passing through parallel links is for a single pair,
per-destination load sharing will overload a single link while
other links will have very little traffic. Enabling per-packet load
sharing allows you to use alternate paths to the same busy
Per-packet load sharing on an interface overrides the global load-sharing configuration.
You configure per-packet load sharing on the input interface. This configuration determines the output interface that Cisco
NX-OS chooses for the packet.
For example, if you have ECMP paths on two output interfaces, Cisco NX-OS uses the following load-sharing methods for input
packets on Ethernet 1/1:
The configurations for the other interfaces have no effect on the load-sharing method used for Ethernet 1/1 in this example.