The purposes of traffic engineering are to optimize the performance of network

to make full use of network resource. And along with the exponential growth of internet

the increase of traffic demand imposes new requirement on the performance of optical network. Firstly

the paper briefly introduces the TE mechanism in MPLS network

then emphasizes on the extensions of routing protocol of GMPLS and two different path algorithms

such as online CSPF and offline Desing-Based routing.