Packet Redundancy Overview
The packet protection feature increases circuit quality and reliability in IP networks that have significant packet loss.
With this feature, each circuit has IP packet redundancy to enable error-free transmission of packets. The packet protector creates and transmits duplicate packets to the IP network. The receiving CTP device processes the redundant packets.
You can set up the packet protector to create and transmit one-for-one duplicate packets to the IP network or to create and transmit duplicate XOR packets. Creating and transmitting one-for-one duplicate packets uses 100% additional bandwidth. Creating and transmitting duplicate XOR packets uses only 50% additional bandwidth.
To use this feature, you configure packet protection on CTP, SAToP, VComp, or CESoPSN bundles. You can specify whether each end of the connection sends and receives duplicate packets, and you can specify the type of duplicate packet.
Setting Buffer Sizes When You Use Cloned XOR Packets
When you use cloned XOR packets, you must set your buffer sizes so that they are large enough to accommodate three packets. You can use the following formula to determine the correct buffer size:
3/[circuit speed/(8 * packet size)]OR((circuit speed / packet size)/8)=packets per secondFor example, a circuit with a speed of 9.6 kbps and 32-byte packets needs a minimum buffer set point that is greater than 80 ms:
(9600/32)/8=37.5 packets per second1/37.5 = 26.67 ms * 3 = 80 ms