Rate oscillations when trying to rate limit

  • Hi,

    I have just signed up to an online backup service and have many GB to upload. I am sitting on a 65/16Mbit link so have reasonable bandwidth and when I'm uploading, the backup server will let me saturate my 16Mbit up. I have been trying to manage this traffic over the past few days to lower the priority of this data transfer so I can guarantee all other traffic is being serviced first. I have tried a number of methods including rate limiting, PRIQ and HSFC but cannot get the behaviour I want. In all cases, once I set a limit below the 16Mbit limit for my link, what I can only describe as "network oscillation" sets in with any queues alternately filling and emptying and the network meter on my PC oscillating from sending close to 0 bytes per second one minute to 16Mbits/sec the next (it really is that quick and the network meter looks like an amplitude modulated sine wave). The rate achieved is also always significantly lower than I expect. If I use PRIQ (which is what I think I really want - the link can use the complete bandwidth if nothing else needs it) I get an average bitrate to the backup server of approximately half my upload link. If I remove the queues, I'm straight back up to 16Mbit/sec. and the rest of the network (half a dozen other machines) is absolutely fine.

    I'm running a 2.1 beta but I don't expect this has anything to do with it as the behaviour is so consistent I would expect it to have been seen on any installation.

    Anyone with any ideas?

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