Proxy to parent but only for big files is possible ?

RouterOS General
1

Hello guys !
Can somebody help me with this situation:
I want to transparent proxy big http downloads to parent proxy but for now without succes:
Here is what I try for now:
This mangle is working for qos …

/ip firewall mangle
add action=mark-packet chain=prerouting comment=\
    "QoS_6 (big-files) supose download files" connection-bytes=1000000-0 \
    disabled=no in-interface=wan1 new-packet-mark=QoS_6_Down passthrough=no \
    protocol=tcp src-port=80,443

This is nat redirection for web proxy:

/ip firewall nat
add action=redirect chain=dstnat comment=\
    "transparent proxy - hotspot net for big files" disabled=no dst-port=80 \
    in-interface=hotspot packet-mark=QoS_6_Down protocol=tcp src-address=\
    192.168.3.0/24 to-ports=3130
add action=redirect chain=dstnat comment="transparent proxy - hotspot net" \
    disabled=no dst-port=80 in-interface=hotspot protocol=tcp src-address=\
    192.168.3.0/24 to-ports=3130

When I use this and watch out bytes (or packet) is growning in secound rule but not in first one .
Proxy is up and running fine also parent is up (squid) and cashe everything … right now is all go via proxy. But I want to somehow mangle only big files and via nat rule redirect to proxy local then parent … or maybe direct to parent …
Can somebody help me with this situation?
Thanks!

2

NAT rules work only for initial packet of connection - you should know the file size before DST-NAT, which is impossible

also, proxy do not have any kind of ‘file size’ matcher. so the only thing you can do is to add direct access rules ( http://wiki.mikrotik.com/wiki/Manual:IP/Proxy#Direct_Access ), so that some files were using parent proxy (like *.rar, *.zip, *mp3, etc), and the rest were requested directly by router