QoS Elastix 5

Implement QoS on Elastix 5

If you need QoS on your Elastix 5 system, this step-by-step guide shows how to create a rule for iptables that tags all traffic from the machine with a higher QoS so as to ensure traffic is given priority.

Step 1: Making sure your QoS rules are applied permanently to Elastix 5

By default, your Elastix 5 system will NOT save any rules applied at runtime. This can however be resolved by adding the iptables-persistent package to your installation as follows:

apt-get install iptables-persistent

This will create a new file in “/etc/iptabes/rules.v4” that will be loaded at each system and service restart.

Step 2: Create a Rule to Tag All Traffice Originating From This Machine

Run the following commands at the command prompt:

iptables -t mangle -A OUTPUT -p udp -j DSCP –set-dscp 56
iptables -t mangle -A OUTPUT -p tcp -j DSCP –set-dscp 56

Step 3: Checking QoS is Applied to Outbound Traffic

Use tcpdump to create a network capture file for you to examine using Wireshark on some other computer:

tcpdump -s 0 -w 247-check-dscp.pcap

Download this file onto your PC and open it with Wireshark. You can check that outbound traffic is indeed being tagged with the correct DSCP value:
Wireshark QoS on Elastix 5

Step 4: Make Sure the Changes are Saved Permanently

Run the following commands at the command prompt:

iptables-save >/etc/iptables/rules.v4

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