Ericsson Cradlepoint endpoints use spillover load balancing, which balances modem usage based on available bandwidth. These endpoints do not perform aggregate or channel-bonded load balancing, meaning they do not sum the bandwidth of attached modems, and combined bandwidth will not appear in online speed tests.
How Spillover Load Balancing Works
Bandwidth-Based Allocation
Each modem connected to the endpoint is assigned a bandwidth value. For example:
Modem A: 1 Mbps available bandwidth
Modem B: 2 Mbps available bandwidth
When a client device initiates an IP connection:
The endpoint checks the available bandwidth of all modems.
The connection is assigned to the modem with the most available bandwidth (e.g., Modem B).
Dynamic Bandwidth Updates After a connection is made, the remaining bandwidth of the selected modem is recalculated. New connections are similarly assigned to the modem with the most available bandwidth at the time. Modem A will only be used if its available bandwidth exceeds Modem B’s.
Uneven Modem Usage Modems may not be utilized evenly, especially when there is a large difference in available bandwidth. For example:
If Modem B is a 4G modem and Modem A is a 3G modem, Modem A may see minimal usage.
Protocols like BitTorrent, which generate numerous IP connections, can utilize both modems effectively.
Limitations
A modem with two SIM slots can only connect to one SIM card at a time, preventing load balancing between SIM cards within the same modem. Load balancing between two SIM cards requires two separate cellular modems.
For details on all available load balancing algorithms, see Load Balancing Algorithms.