We have 2 internet connections coming in to our building - neither are great (2 different routers from different providers). Are there technologies in Network Switches to support active switching or load balancing across the two connections? I know this maybe standard but I am not familiar with the names of the protocols to do this.

What we want to achieve is for the switch to automatically send data down connection A if connection B if it is not performing well, and vise-versa. Equally if both connections are performing for the load to be split between both connections? Crucially though, for it to do this without manual intervention all the time. And lastly if we can also set what type of traffic should be prioritised and/or by the device on the network (so for example people cabled computers take precedence over mobile phones).

I'm sure this is common knowledge but I need to start somewhere. Searching on Google just gives lot of manuals to various switches but I need that basic understanding first, so anything which could aid that learning would be helpful.

2 Answers 2


Yes, there are devices which can load balance and/or provide fail-over, but specific product and resource recommendations are explicitly off-topic here.

You will want to be very careful about load balancing. You will get out-of-order packet delivery and asymmetric routing, which can cause problems and actually slow your Internet speed. This will also break NAT unless you have a public IPv4 address which both ISPs will route. Getting your own block of IPv4 addresses can be costly, and it requires both ISPs to cooperate.

While it sounds like a good idea on the surface, this is not something you should attempt unless you really know what you are doing.

  • Interesting, thanks for the advice. Not looking for specific products so don't worry. Is it common practice to use fixed routing - so to be able to get data from ports 1-12 to use Connection A and 13-24 to use Connection B?
    – tim.baker
    Apr 21, 2016 at 16:13
  • Depending on the device and software, you could load balance flows instead of packets. This avoids some of the problems.
    – Ron Maupin
    Apr 21, 2016 at 16:16

If you are using Cisco router with both Internet connections coming in to the same router you could:

  1. Configure both WAN interfaces
  2. Configure IP SLA
  3. Map SLA to track object
  4. Add 2X default routes matching the separate track objects removing the route if it does not meet the required criteria of the SLA probe.

The SLA functions in Cisco IOS allow you to track: (From Cisco Website) •Connection loss


•Round-trip time threshold

•Average jitter threshold

•One-way packet loss

•One-way jitter

•One-way mean opinion score (MOS)

•One-way latency

So you could essentially have both WAN interfaces active whilst removing a route if it is performing badly.


  • Further to my response: If you need to lower the priority of people using mobile devices via wifi for example. You would generally need to configure QOS. Some APs allow you to tag all incoming packets with a DSCP value. When the packet from that AP reaches the router it inspects it and can set a priority based on the DSCP value set. This does need an engineer to configure as it gets quite complex. Apr 22, 2016 at 1:57

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