The IP Layer 4 load-balancing option includes the TCP/UDP source and destination port numbers in addition to the source and destination IP addresses in per-flow hashing of IP packets. By including the Layer 4 information, a source address/destination address default hash flow can be subdivided into multiple finer-granularity flows if the ports used between a source address and destination address vary.
Layer 4 load balancing is configured at the system level using the config>system>l4-load-balancing command. It can also be configured at the router interface level or the service interface level (IES and VPRN). Configuration at the router interface or service interface level overrides the system-level configuration for the specified interface or service.
For LSR LDP ECMP, Layer 4 load balancing is configured using the lbl-ip-l4-teid option in the lsr-load-balancing command at the system level or router interface level. Configuration at the router interface level overrides the system-level configuration for the specified interface.
Layer 4 load balancing can also be configured at the service level for Epipe and VPLS services. Layer 4 load balancing at the service level is not impacted by Layer 4 load balancing at the system, router interface, or service interface levels.