What Causes These Spikes in the Bandwidth Graph?

Discussion in 'Tomato Firmware' started by The Doctor, Jan 14, 2009.

  1. The Doctor

    The Doctor LI Guru Member

    I have been running tomato for quite some time on my buffalo WHR-HP-G54, version 1.09 had over a year worth of uptime when I finally upgraded and restarted it. The upgrade was due to the fact that it would sometimes forget to renew the DHCP lease automatically after I upgraded to Verizon FiOS. Version 1.23 has been up and running for about a month, the problem looks to be fixed:)

    Anyway, there does not actually appear to be any problem with the router, it works fine. My current service is Verizon FiOS 20/20, the router is connected directly to the ONT with a cat 5 cable, the coaxial connection is not used, nor is the original ActionTec router supplied by Verizon.

    Back when I was with Comcast, where the connection was only 8/2, the bandwidth graphs were always fairly smooth. With the FiOS connection, they are usually smooth, but when I start moving a lot of data the graphs sometimes gets these huge spikes were choose way up, goes way down, then goes back to the line it was on before. It typically doesn't do this if the combined throughput is under 10 Mb/sec, but almost always does when it gets close to 20, especially if there is a lot of traffic in both directions. Is this an indication the router is close to some kind of internal limit? As I said, there does not appear to be any problem with the connection, it has not had a moment of downtime since I upgraded to 1.23 a month ago. I am just curious about if this means anything.

    Thank you

    Added: the spikes do not show up on a bandwidth graph in eMule, which is usually one of the application using most of the bandwidth. It also does not show up on the bandwidth graph in Windows XP, so I don't believe it actually is showing a huge swing in throughput, I think it is just a display thing.

  2. Planiwa

    Planiwa Network Guru Member

    Looks like a sampling (dis)continuity artifact. It'll be even more interesting if you change Avg from 2x to Off. (You can smooth out the spikes with wider averaging, or disappear them with longer sampling time intervals.) Bonus question: why are the spikes always up, then down?
  3. azeari

    azeari LI Guru Member

    looks like burst bandwidth at work over here (=
  4. bogderpirat

    bogderpirat Network Guru Member

    it's a sinus rhythm. your internet is alive.

  5. Toastman

    Toastman Super Moderator Staff Member Member

    These spikes can be caused by something stopping/slowing down your PC to Router connection temporarily.

    Check for the famous "half-open TCP connections" limit in Windows and increase if necessary by using this patch - raise it to e.g. 500.


    Check also that it is not caused by Windows XP's "Wireless Zero Configuration" service, by using your adapter's own connection software if possible.

    WZC is known to go wandering off looking for other routers to connect to at regular intervals!
  6. szfong

    szfong Network Guru Member

    You have pretty high bandwidth. It's probably malware infested pc's (1 or more) can cause bandwidth graph spikes on such high speeds. It needs to send small messages to an irc channel telling it that it is alive and awaiting instructions (aka Zombies). Try to find the source pc, Linux/BSD based computer don't seem to be as common. When I let others use a windows pc for a while, they get infested pretty quick. Some people will click at whatever windows pop up. Any old (un-updated/patched) windows pc's/server connected to the internet w/o a firewall will get infected within hours, even by doing nothing.
  7. callous

    callous Network Guru Member

    The upward spike is above what is rated for your speed profile, while the downward spike is almost the exact amplitude as the up spike.

    Im guessing it's the throttling by your internet provider. Remove the throttling and your speed will actually go and stay at where the high spike is
  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice