MAINTAINING QUALITY OF PACKET TRAFFIC IN OPTICAL NETWORK WHEN A FAILURE OF AN OPTICAL LINK OCCURS

摘要

Interworking of optical protection in an optical network and IP-layer protection in the Internet is achieved by configuring optical links to form a part of a ring network and by arranging different protection types for different links. Each optical link is provided with an appropriate protection level corresponding to the nature of Internet traffic being transmitted over the link. The highest pro-tection level is achieved with 1+1 protection. The optical layer can offer this protection for high priority Internet traffic that does not tolerate delay. The middle and the low protection level are achieved with 1:1 protection. The low protection level of a link does not guarantee uninterrupted transmission of the Internet traffic, in case of link failure caused by a fiber cut. Optical signaling at the optical layer takes care of protection wherein the IP-layer does not know when protection actions are carried out. At the IP layer different quality-of-service parameters are assigned to the optical links of different priority. Then routers create different routing tables for different quality-of-service classes.