120/5 mbps connection is VERY asymmetric, and implies cable. Cable companies
often prioritize traffic in unusual ways. Even if they don’t, the acks going
upstream for payload coming down could saturate your upstream without uploading
any content at all. I would put limiters on your traffic to make sure that you
stay below saturation upstream and down, allowing any local packet queueing or
prioritization to actually matter. If you saturate your connection, then
you’re letting the upstream provider decide what traffic to throw away.
I have had no problem with bitTorrent behind a PFSense soekris 6501 or on
OpenBSD on the soekris on 25/15 or 50/50 connections. When using OpenBSD I had
traffic control rules to prioritize acks and other <500 byte packets over
larger packets.
And yeah, wireless is evil. Don’t trust performance tests on wireless.
ED.
> On 2015, Dec 20, at 8:14 PM, Freek Dijkstra <[email protected]> wrote:
>
> Hi Thomas,
>
> [...]
>> When I'm part of any kind of p2p "swarm", I can't upload reliably. It's so
>> bad
>> that I've rarely ever seen more than 20KBps per peer, and it's usually
>> between
>> 0 and 10KBps (5KBps is pretty average :o).
>>
>> I did some testing this weekend, and tried out the latest stable pfSense on
>> it
>> (I was running Debian Sid), and things improved a bit. Now I'm using an RT-
>> AC66U
> [....]
>
> First of all, your network setup if not entirely clear. Is your p2p
> client running on your Soekris net6501?
>
> If so, is that wifi network with the Asus RT-AC66U between the Soekris
> and the upstream network?
>
> If not, why do you think the Soekris hardware is responsible for the
> poor network performance?
>
> My first two suspects of bad network performance would be:
>
> 1. Poor wifi. What is the packet loss and jitter (variation in latency)
> between the wifi client and wifi AP? Ideally, this should be about 1 ms
> RTT without much fluctuations, but 3 or 5 ms is usually acceptable too.
> If you see latency over 10 ms, or over 5% packet loss, that is most
> likely the culprit. Look into the location of the wifi, the channels
> used by you and neighbours, etc. If you haven't done so, download a wifi
> scanner to find out which channels are in use, and how strong they are.
> Note that for 2.4 GHz (802.11g, 802.11n), an AP in e.g. channel 5 may
> still interfere with channels 3 thru 7. 5 GHz (802.11n, 802.11ac) has
> less users, but is more susceptible to interference by walls, floors and
> doors.
>
> 2. Network saturation because of the use of UDP-based p2p traffic. TCP
> has a fairly commanding congestion control algorithm, which
> significantly backs-off in case of congestion. A fair portion of p2p
> clients uses UDP, which lacks congestion control, and may continue to
> send traffic. Unfortunately, this often results in higher latency,
> collisions, and ultimately collapse of performance. It certainly pays of
> to configure your p2p client to only use at max 50-75% of your upstream
> bandwidth capacity.
>
> Other sources might be poor TCP congestion control tuning, buffer bloat
> or the opposite (too small buffers), poor Ethernet flow control, poor
> upstream network. Insufficient TCP-offloading in your NIC, or -more
> generally- not powerful enough CPU in your Soekris 6501 would be at the
> bottom of list of suspects.
>
> Hope this works.
>
> Freek
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