Latency, TCP ACKs and upload needs

Tony Finch dot at
Wed Apr 20 16:12:36 UTC 2016

Leo Bicknell <bicknell at> wrote:
> 1460 byte payloads down, maybe 64 byte acks on the return, and with SACK
> which is widely deployed an ACK every 2-4 packets.  You would see about
> 2,140 packets/sec downstream (25Mbps/1460), and perhaps send 1070 ACKs
> back upstream, at 64 bytes each, or about 68Kbps.  Well under the 1Mbps
> upstream bandwidth.

Note that with delayed ACKs (RFC 1122) there is an ACK for every other
packet; SACK should do better than that.

f.anthony.n.finch  <dot at>  -  I xn--zr8h punycode
Humber, Thames: Northwest, veering north or northeast, 4 or 5. Slight or
moderate. Fair. Good.

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