Modern TCP stacks have become efficient at dealing with latency by adding TCP Window Scaling and Selective Acknowledgements. However, TCP is still vulnerable to packet loss and this has a drastic impact on network performance. Where WAN performance is limited by the negative effects of packet loss and re-transmissions, Packet Loss Recovery can be configured.
![device-configure-systemsettings-optimizationsettings-packetlossrecovery-3](http://wanos.co/docs/wp-content/uploads/2020/12/device-configure-systemsettings-optimizationsettings-packetlossrecovery-3.png)
![systemsettings-optimizationsettings-optimizationsettings-plr](http://wanos.co/docs/wp-content/uploads/2016/04/v41_systemsettings-optimizationsettings-optimizationsettings-plr.png)
Why Packet Loss is important?
- Loss has a severe impact on TCP performance: For example TCP throughput over a 100 Mbps link is limited to 1 Mbps at 80 ms and 2% loss.
- More businesses are connecting their offices via low cost VPN links. These typically have 1% loss rate, which is 10 times higher than MPLS links.
- SLA’s provide a false sense of security. A 3+% loss for an hour a day means providers can still meet a very low monthly average loss rate SLA.
- Packet Loss is higher in emerging and developing countries. On average 2% or more.
The Packet Loss Recovery field indicates the level of aggressiveness. Level 2 (Conservative) is the default and recommended setting. Levels can be increased for higher latency links.
Starting in version 4, Peers are automatically detected and configured with Packet Loss Recovery enabled.
![device-reports-peerstatus-plr-enabled](http://wanos.co/docs/wp-content/uploads/2020/12/device-reports-peerstatus-plr-enabled.png)
![device-reports-peerstatus-plr-disabled](http://wanos.co/docs/wp-content/uploads/2016/04/device-reports-peerstatus-plr-disabled.png)
![network-peerstatus1](http://wanos.co/docs/wp-content/uploads/2016/04/v41_network-peerstatus1.png)
![network-peerstatus2](http://wanos.co/docs/wp-content/uploads/2016/04/v41_network-peerstatus2.png)
Under PLR field, Streaming means that Packet Loss Recovery is enabled. Stateless means Packet Loss Recovery is disabled. Packet Loss Recovery (PLR) can be disabled/enabled by navigating the Web User Interface > Configure > System Settings > Optimization Settings.
Information for Wanos version 3
To enable Packet Loss Recovery, configure a Multisite first then change Packet Loss Recovery field in Configure > System Settings > Optimization Settings.
Sample Scenario
- Network/Mask: 192.168.1.0/27
- Wanos-HQ: 192.168.1.16
- Wanos-Branch: 192.168.1.17
- Packet Loss Recovery: 1 (default)
Screenshot of Add Site template found in Configure > MultiSite
Screenshot of a MultiSite rule added in Wanos-HQ
Screenshot of a MultiSite rule added in Wanos-Branch
Check the status of Packet Loss Recovery by navigating to Network > Peer Status.