Why You Should Use IPMP

Different factors can cause an interface to become unusable. Commonly, an IP interface can fail. Or, an interface might be switched offline for hardware maintenance. In such cases, without an IPMP group, the system can no longer be contacted by using any of the IP addresses that are associated with that unusable interface. Additionally, existing connections that use those IP addresses are disrupted.

With IPMP, one or more IP interfaces can be configured into an IPMP group. The group functions like an IP interface with data addresses to send or receive network traffic. If an underlying interface in the group fails, the data addresses are redistributed among the remaining underlying active interfaces in the group. Thus, the group maintains network connectivity despite an interface failure. With IPMP, network connectivity is always available, provided that a minimum of one interface is usable for the group.

Additionally, IPMP improves overall network performance by automatically spreading out outbound network traffic across the set of interfaces in the IPMP group. This process is called outbound load spreading. The system also indirectly controls inbound load spreading by performing source address selection for packets whose IP source address was not specified by the application. However, if an application has explicitly chosen an IP source address, then the system does not vary that source address.