TransparentTrafficShaper

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Introduction

This example shows how to configure a transparent traffic shaper. The transparent traffic shaper is essentially a bridge that is able to differentiate and prioritize traffic that passes through it.

Consider the following network layout:

Transparent-shaper.png

We will configure one queue limiting the total throughput to the client and three sub-queues that limit HTTP, P2P and all other traffic separately.

Quick Start for Impatient

Configuration snippet from the MikroTik router:

/ interface bridge 
add name="bridge1"
/ interface bridge port 
add interface=ether2 bridge=bridge1 
add interface=ether3 bridge=bridge1 
/ interface bridge settings
set use-ip-firewall=yes

/ ip firewall mangle 
add chain=prerouting protocol=tcp dst-port=80 action=mark-connection \
    new-connection-mark=http_conn passthrough=yes
add chain=prerouting connection-mark=http_conn action=mark-packet \
    new-packet-mark=http passthrough=no
add chain=prerouting p2p=all-p2p action=mark-connection \
    new-connection-mark=p2p_conn passthrough=yes
add chain=prerouting connection-mark=p2p_conn action=mark-packet \
    new-packet-mark=p2p passthrough=no
add chain=prerouting action=mark-connection new-connection-mark=other_conn \
    passthrough=yes
add chain=prerouting connection-mark=other_conn action=mark-packet \
    new-packet-mark=other passthrough=no

/ queue simple 
add name="main" target-addresses=10.0.0.12/32 max-limit=256000/512000
add name="http" parent=main packet-marks=http max-limit=240000/500000 priority=1
add name="p2p" parent=main packet-marks=p2p max-limit=64000/64000 priority=8
add name="other" parent=main packet-marks=other max-limit=128000/128000 priority=4

Explanation

Each piece of code is followed by the explanation of what it actually does.

Bridge

/ interface bridge 
add name="bridge1"
/ interface bridge port 
add interface=ether2 bridge=bridge1 
add interface=ether3 bridge=bridge1

We create a new bridge interface and assign two ethernet interfaces to it. Thus the prospective traffic shaper will be completely transparent to the client.

V3

/ interface bridge settings
set use-ip-firewall=yes

Bridged packets behavior is changed on RouterOS v3. Use command to make bridged packets go trough 'ip firewall', by default bridged traffic is not going over 'ip firewall'.

Mangle

/ ip firewall mangle 
add chain=prerouting protocol=tcp dst-port=80 action=mark-connection \
    new-connection-mark=http_conn passthrough=yes
add chain=prerouting connection-mark=http_conn action=mark-packet \
    new-packet-mark=http passthrough=no

All traffic destined to TCP port 80 is likely to be HTTP traffic and therefore is being marked with the packet mark http. Note, that the first rule has passthrough=yes while the second one has passthrough=no. (You can obtain additional information about mangle at http://www.mikrotik.com/docs/ros/2.9/ip/mangle)

/ ip firewall mangle 
add chain=prerouting p2p=all-p2p action=mark-connection \
    new-connection-mark=p2p_conn passthrough=yes
add chain=prerouting connection-mark=p2p_conn action=mark-packet \
    new-packet-mark=p2p passthrough=no
add chain=prerouting action=mark-connection new-connection-mark=other_conn \
    passthrough=yes
add chain=prerouting connection-mark=other_conn action=mark-packet \
    new-packet-mark=other passthrough=no

Same as above, P2P traffic is marked with the packet mark p2p and all other traffic is marked with the packet mark other.

Queues

/ queue simple 
add name="main" target-addresses=10.0.0.12/32 max-limit=256000/512000

We create a queue that limits all the traffic going to/from the client (specified by the target-address) to 256k/512k.

/ queue simple 
add name="http" parent=main packet-marks=http max-limit=240000/500000 priority=1
add name="p2p" parent=main packet-marks=p2p max-limit=64000/64000 priority=8
add name="other" parent=main packet-marks=other max-limit=128000/128000 priority=4

All sub-queues have the main queue as the parent, thus the aggregate data rate could not exceed limits specified in the main queue. Note, that http queue has higher priority than other queues, meaning that HTTP downloads are prioritized.