Bufferbloat

[Christmas themed thank]

I only just found out about Bufferbloat.

When you're downloading/uploading, if your ping skyrockets and then when the download/upload finishes, it goes back to normal, you've got Bufferbloat.

QOS in the Gargoyle firmware didn't help (even though it is designed to reduce the ping when downloading/uploading) so I installed OpenWRT on my TP-Link WDR3600, after researching the issue. I also installed the SQM QoS package. It turns out I didn't really need the package as OpenWRT reduces bufferbloat so much anyway. I'm sure the package helps a bit however.

So if you're having issues with the ping when downloading, see if your router supports OpenWRT.

 

[Steveocee]

This is expected behaviour though. If you're hammering the bandwidth downstream then ping takes a backseat.

Either limit your download speeds or put up with a small increase in ping time whilst the download finishes.

 

[Caged]

It also can't be cured by just changing settings on the router at the end of it.

 

[Christmas themed thank]

I suggest you have a read of this - it explains very nicely why this works and keeps the pings very low when downloading.

 

[Steveocee]

I suggest you have a read of this - it explains very nicely why this works and keeps the pings very low when downloading.

I've had a bit of a skim through that and in short it's just queue management. It doesn't mean you can carry on downloading full boar whilst reducing ping times, that simply ISN'T possible.

It is just packet scheduling and whilst capping your download speeds off so as not to saturate the bandwidth, in short your pings will stay the same but your download will come down that little bit slower. There isn't a cure for maxxing your bandwidth other than buying more bandwidth.

I apply similar simple queue management to my guest network constantly so that guests won't ever impact me (only have 20/1 so upload is precious).

 

[Steveocee]

No idea how I multi posted.

 

[Christmas themed thank]

I'd say the 500Kb hit in order to keep the ping times low when downloading is worth it, wouldn't you?

 

[Steveocee]

I'd say the 500Kb hit in order to keep the ping times low when downloading is worth it, wouldn't you?

Depends on how much bandwidth you have. I currently have 20/1 and I give guests a whopping 5/256.

I'm yet to extend my queue tree so it prioritises my traffic over the guest network so I can squash them harder if I need to.

**Also looking at ways of getting more bandwidth.

 

[Tephnos]

Had that on my 488kbp/s upload on my ADSL connection.

Anger.

 

[Rabtech]

Correct me if I'm wrong but it isn't bufferbloat as such - just not enough resources for what you are doing and not reducing the maximum upload enough depending on your download speed.

I've found that ISP supplied routers are of course budget ones, can simply only 'handle' a limited amount of connections at once i.e. they don't have the CPU/ram resources available to manage what you are trying to do, so packets get queued/dropped and latency rises steeply due to timeouts and retransmit requests.

Tuning your connection settings if it's P2P software you are using should improve things massively. High end routers can easily handle thousands of simultaneous connections, the N56U upwards are famous for it for example.

 

[Christmas themed thank]

It is bufferbloat - most consumer modems aren't optimised to reduce it so you have to get your router setup to overcome it.

Essentially your modem is sending data too quickly and so it has to be buffered - that's the delay you get.

 

[Orcvader]

I had this on my ADSL connection. Moving to FTTC even using the same HH3 made it a lot less noticable.