It sounds like the sender has a buffer bloat issue. I see the same thing
with bittorrent and tcp. If I rate limit my 150mb connection to 100mb, I
will see about 30-40mb of retransmissions, for a total of ~135mb of
ingress. Even though I limit only to 100mb.

If I trace route the offending senders, I always see a 3000ms+ ping 1-2
hops before I reach them.

Tcp treats the buffer bloat as packet loss, flooding the receiver.

On Dec 9, 2016 1:20 PM, "George Amanakis" <g_amanakis@yahoo.com> wrote:

> Dear All,
>
> regarding the issue about WAN ingress rate with many concurrent TCP
> downloads, it seems that all the excess ingress rate on the WAN interface
> are TCP retransmission packets (Wireshark). After the latest commit 78ff814
> in cobalt, ping times while using TCP BitTorrent improved from ~1000ms to
> ~300ms (concurrent connections 55). If I reduce the concurrent connections
> to 30 I get ping times lower than 70ms.
>
> Best regards,
> George
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