How do routers combine WAN and LAN traffic (packet data over wifi and ethernet)?

Question

In my office, we have a leased line connection which is shared by some 20 users over wi-fi. This causes congestion on the router's end, resulting in slow speed due to high packet drops (and consequent resends).

If someone uses the internet over a lan cable now, his internet also gets substantially reduced.

I have been trying to read up on this, but haven't come across anything substantial as to why the performance of the LAN cable should get affected.

Everyone (in office) seems to be under the impression that if we are on LAN ethernet cables, the network congestion doesn't affect it unless you hit the capacity of the medium itself, and hence, the speed should be okay over the cable.

My guess is, since all is TCP/IP data, the packet drop because of the wifi is significantly affecting the ability of the router to keep serving packets over ethernet as well (Packets dropped over wifi means router has to resend them, and hence it's queue for resending items is significantly high)

So my question is, how does a typical router handle wifi and ethernet packets togather? Do they both get sent through common queue(s) etc? References to diagrams for visualization would be a big help.

Also, what is the specific term for this kind of multiplexing? I have been googling for hours but I can't find much relevant information.

Answer 1

This causes congestion on the router's end,

Likely no. It causes congestion in the air. Wif frequencies have very limited bandwidth.

Everyone (in office) seems to be under the impression that if we are on LAN ethernet cables, the network congestion doesn't affect it unless you hit the capacity of the medium itself, and hence, the speed should be okay over the cable.

Everyone in the office is right. Modern gigabit ethernet is 1gb full duplex PER CABLE - ports do not collide. Air is neither full duplex on a frequency (you can not send and receive at the same time) nor per cable.

My guess is, since all is TCP/IP data, the packet drop because of the wifi is significantly affecting the ability of the router to keep serving packets over ethernet as well

Let me forulate it non-diplomatic. For a professional admin (only those should be on this board) you are terrifically ignorant how a network works. No, it does not affect the router. The router sends IP packets to MAC addresses and whether they get lost on the WIFI or not on the cable does not affect each other.

Until you overload the external line with all the resends necessary, or the CPU / Memory of the router, in which case you got a wonderfully cheap router that should never be used in an office like this.

how does a typical router handle wifi and ethernet packets togather?

I would say it does not, as the TYPICAL router does not have WIFI. Those mostly are cheap consumer grade end usnits or small office setups - most routers wont know wifi.

If it does - it is just another switch, so to say. The router routes packets to destination IP Addresses and then on the lower medium to MAC addesses.

Do they both get sent through common queue(s) etc?

IMplementation detail. How many cylinders does a car have? Are there only 4? Always? Cheap reouters will ahve few queues. Better ones have one per port - wifi being one port, as is every cable - or even software configurable ones.

You can see WIFI as one ethernet broadcast domain. Every LAN port is one, too.

I have been googling for hours but I can't find much relevant information.

Try some really basic introduction. You mix up a lot of stuff becuase you basically have no clue how a network operates physically.

Basically - only people with no understanding or trying t be super cheap ty to run an ofice of 30 people over wifi. Wifi is terribly compared to cable. It is good for conferences, meeting rooms, the tablet etc (light users), but I would not run workstations on it. Not if "getting work done" is the goal.