Link Aggregation


  • In houses that have several devices connected through ethernet you are going to need a switch to extend the router's ethernet ports, and not being able to set up LAG to connect the switch to the router can become a bottleneck when wifi and ethernet devices start streaming to each other (e.g., think steam link). This is especially true if you add a NAS to the mix.

    Most routers (and definitely all routers in this price range) have the option to set up Link Aggregation.


  • @Alejandro-Armelles-Bello said in Link Aggregation:

    Most routers (and definitely all routers in this price range) have the option to set up Link Aggregation.

    Please forgive my ignorance, but I thought the primary reason for link aggregation was to double ISP data rate to the LAN, not to perform performance on the LAN itself. Can't you just run an EN cable from one of the router's LAN ports to an unmanaged switch?

    Again, calling me a "novice" is being complimentary, but I'm here to learn.


  • This post is deleted!

  • @jsrnephdoc No need to apologize, we are all learning here.

    LAG allows you to use several ethernet cables to connect two devices. It is not limited to connecting a modem to a router.

    So, yes, in my scenario you have to run a cable from the router to the switch. But any communication between the two will be limited to 1Gbps. Link aggregation allows to connect and utilize two cables to send the data between the router and switch (thus effectively giving you a ~2Gbps connection between them).

    E.g., You have a NAS that is using LAG to connect to the switch (that gives the NAS an effective bandwidth of ~2Gbps to the switch, most NAS have this feature). Now three wireless devices are trying to access it through the router (the router is your AP for all the wifi devices in the house). Since the router is connected to the switch through a single 1Gbps connexion, the three wireless devices will not be able to pull data at a rate higher, on aggregate, of 1Gbps, even if the NAS is capable of more.
    Another example can be having an Xbox, a computer, and an OTA receiver connected to the switch and all trying to stream something (games, recordings, etc.) to several wifi devices. The connection between the router and the switch will be a bottleneck. Each wired device has a bandwidth of 1 Gbps to the switch (so in theory they could, in aggregate, use up to 3Gbps when communicated to the wireless devices), but without LAG they will have to share the 1 Gbps limit when reaching devices connected to the router. LAG will give you a 2 Gbps connection (still less than the potential 3 Gbps they could use, but 100% more than you get with a single cable).

    I am using LAG with two ports as an example, which is what most routers allow. Certain devices actually allow to bond 3 or more ports.



  • @Alejandro-Armelles-Bello , thanks SO much for that lucid explanation. I still have one question, however. I'm familiar only with the Alien router. It's limited to 1 gbit/sec input from the WAN (has only 1 EN WAN port), so using two of its LAN ports to the same EN switch will increase LAN traffic only if the switch also supports multi-cable connections to individual clients, but of course won't permit more than 1 gbit/sec to a client device through the router from the internet because that's limited by the Alien's single WAN port.

    My Netgear CM1200NAS cable modem would support 2 gbit/sec WAN traffic if the Alien had two WAN ports, but that's a hardware limitation of the router. Is it possible that as data rate needs expand we might see a next generation Alien that supports bonding of two WAN ports, AND bonding of two LAN ports, AND is capable of extending the life of the routers we now own by using our current Aliens as MESH devices. A corollary inference (more a statement than a question, because I never even considered this previously), is that my brand new house that I don't even own yet but which is now all "wrapped up" (drywall on the studs, paint on the drywall), in which I had star topology EN run throughout the house, is ALREADY obsolete as far as some homeowners with NAS storage and enormous gaming data appetites would be concerned?

    The mantra for the "Rich Housewives of the [name your favorite upscale city]"generation has singularly been "you can never be too rich or too thin." So far as network traffic capacity is concerned, however, it sounds as though that's turned on its head, to "you can never be too rich or too fat" (or perhaps the appropriate adjective is "capacious."


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