The increased use of 40G client and network interfaces has driven new Protocol and Performance verification. This session will review 40G Client interface testing using SONET/SDH/OTN protocols over NRZ optical interfaces, as well as network testing of OTN and Ethernet over OTN using DPSK and DQPSK optical interfaces. Introductory discussions on various levels of protocol analysis, traffic generation, BER testing, point to point testing and through mode testing will be covered.