Understanding ECMP Path Selection and Load Balancing

NetVisor supports a number of technologies for traffic load balancing and path redundancy, such as LAG and vLAG.

For Layer 3 designs, NetVisor OS supports standard routing protocols such as OSPF and BGP. When multiple next hops exist, NetVisor OS employs ECMP (Equal-Cost Multi-Path) routing to choose amongst the available paths for traffic load balancing and redundancy.

In order to perform path selection in hardware, ECMP uses a high-performance technology called packet field hashing.

What that means is that the hardware extracts a number of packet fields and with them performs a special calculation to generate a hardware index. Such index is then used to select a next hop for an ECMP routing decision. Up to 16 next hops are supported for load balancing by the hardware-based hashing function.