The ip cef loadsharing algorithm original command will cause a router to be prone to Cisco Express Forwarding (CEF) polarization, which occurs when multiple routers in sequence use the same loadbalancing mechanism.
The ip cef loadsharing algorithm original command configures CEF to load balance based only on the source and destination. Universal mode improves on the original CEF loadbalancing algorithm by using a source, a destination, and a 32bit Universal ID as a hashing seed. Because each router uses a different Universal ID, each router will produce different hashing values, thereby avoiding CEF polarization by enabling each router to load balance differently. Universal mode is enabled by default or by issuing the ip cef loadsharing algorithm universal command. Because universal mode is enabled by default, the no ip cef loadsharing algorithm command enables universal mode, thereby avoiding CEF polarization.
The ip cef loadsharing algorithm tunnel command avoids CEF polarization. The tunnelmode algorithm uses an improved universalmode algorithm that works well in environments with a small number of source and destination pairs, which often occurs with tunnels.
The ip cef loadsharing algorithm includeports source destination command avoids CEF polarization. This command configures CEF to not only use the universal loadbalancing algorithm but also to consider Layer 4 source and destination port information.