VMG1312-B10A: QoS

The ZyXEL VMG1312 has QoS enabled by default with a set of default rules giving priorities to various protocols.

Initial findings show that the default settings may not ideal.

The affect of disabling QoS

Here we are running a backup job, an rsync (over ssh). Just after 7am QoS is disabled for around 30 minutes. The latency (blue) immediatly jumps up to an average of 350ms. It was less than 20ms with QoS enabled.

Standard QoS enabled, then disabled, then enabled

Problems with default settings

With the default settings, running an rsync over ssh backup, kills DNS lookups completely! SSH has a higher priority than DNS, and with all the SSH traffic DNS lookups can't get a word in edgeways.

AA Default Settings

We set the QoS be simply based on packet size. We deactivate the various default Classes and Queues and rely on the setting to let small packets jump the queue. This typically gives VoIP, DNS and other 'real time' protocols priority. This is similar to the way that the core routers at the AAISP side work.

QoS setting as set by AAISP, simply based on packet size

QoS on our CQM Monitoring

Graph showing affect of enabling the 'Packet Length' QoS. When disabled, high latency and slight packetloss. Once enabled, online activity was unaffected by the 10Mb/s upload.

Customer Feedback

We welcome any customer feedback as to these QoS settings. We're happy for customers to modify their config if they would like, but these settings would get overwritten if a config is ever send from the AAISP side to the router.