Prioritize ACK frames over traffic in ADSL environment

RouterOS General
1

Hello, i seem to have a situation where ack packets are being dropped by the adsl modem.
The connection is 12MB/573kbps, but whenever there is upload traffic going on, the inbound speed fluctuates wildly, from 3 to 7, and no more than 7mbps.

There is a bridged RB750 between the modem and the network, but i can’t change the modem configuration, nor i can make the mikrotik to be the gateway.


I need a way to limit the upload traffic, prioritizing those ack’s somehow.


Has anyone dealt with this situation before? How did you managed to get a usable connection?


Regards!

2

I mangle tcp packets with the ack flag set and size < 64, then put those high up in my queue tree, which has an upload bandwidth slightly lower than the actual speed so as to avoid drops/buffering by the modem.

Try this on:

/ip firewall mangle
add action=mark-packet chain=forward new-packet-mark=ack-mark out-interface=eth1 packet-size=0-64 passthrough=no protocol=tcp tcp-flags=ack

/queue tree
add max-limit=550k name=upload-q parent=eth1
add name=ack packet-mark=ack-mark parent=upload-q priority=1