Hi!
I'm using a Netgear centria as an internet router, and I found out today that I was not reaching the ISP promoted bandwidth speed.
Of course I thought this was just one of those "Pay for 1000, get 100" things ISPs usually do when going popular, but unfortunately for me, I switched over the internet cable from the ISP to a computer under gigabit link and this effectively seems to be some sort of limitation on my router or misconfiguration.
Even though Netgear advertised this product to have all gigabit links, including Internet port as well, I literally get exactly 100 Mbps numbers on all the testing tools available out there.
As I mention before, I thought this value was too rounded to be HW limitation on my end, but the computer tests don't lie.
I went ahead and run a couple of iperf against the internal bridged part of the lan, all going through gigabit interfaces of course, and I found this really strange thing that is totally consistent across tests:
root@centria:~# iperf -s
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 85.3 KByte (default)
------------------------------------------------------------
[ ID] Interval Transfer Bandwidth
[ 4] 0.0-10.1 sec 313 MBytes 261 Mbits/sec
[ 4] 0.0-10.1 sec 328 MBytes 273 Mbits/sec
[ 4] 0.0-10.1 sec 327 MBytes 271 Mbits/sec
root@centria:~# iperf -c remote
------------------------------------------------------------
Client connecting to remote, TCP port 5001
TCP window size: 74.4 KByte (default)
------------------------------------------------------------
[ ID] Interval Transfer Bandwidth
[ 3] 0.0-10.0 sec 65.8 MBytes 55.1 Mbits/sec
[ 3] 0.0-10.0 sec 66.0 MBytes 55.3 Mbits/sec
[ 3] 0.0-10.0 sec 66.1 MBytes 55.4 Mbits/sec
As you can see, there's a difference in performance on incoming and outgoing traffic of 5 times. I suspect this is also related to my main problem, which is paying 3 times more than I'm actually getting.
I did switch on hw and sw flow offload, with observable difference but not that significant. It went from 100mbps to 112mbps when using hw one.
I'm pending a test on using a port on the internal vswitch as incoming internet port to double check this is not some misbehaving on the internet port, but I kind of doubt it's going to change a thing.
Any ideas what parameters I could tune to fix this?
