f T-MPLS (Transport MPLS) and PBB- TE (Provider Backbone Bridging-Traffic Engineering) which offers connection oriented layer 2 services. T-MPLS has been replaced by MPLS-TP (MPLS Transport Profile) which is a joint standardization effort between the ITU-T and the IETF and is under development. ITU-T ceased work on T-MPLS in December 2008, in favor of MPLS-TP standardization. MPLS-TP activity was established after IETF raised concerns over T-MPLS technology, mainly about its incompatibility with the already established Transmission Networks IP/MPLS. The most important difference between T-MPLS and MPLS-TP is that MPLS-TP defines separate OAM mechanism. On the other side of the coin, the IEEE, originator of the first Ethernet standard has spent a tremendous number of hours to evolve it into a connection-oriented technology to make it suitable for carriers. As the demand for data services started to appear in the late twentieth century, IEEE refocused its attention towards Ethernet. The work from IEEE came in the form of various standards. Starting from Media Access Control Bridging (IEEE 802.1D), Virtual Local Area Network (IEEE 802.1Q) and Provider Bridging (IEEE 802.1d), and then towards Provider Backbone Bridging (IEEE 802.1ah), and finally towards its connection oriented variant PBB-Traffic Engineering (IEEE 802.1AQay). PBB-TE builds upon the previous standards to provide a network solution designed specifically for carrier class transport networks. 7.4.2.3.4 Key Standards Table 7.5 further shows a list of key standards for Carrier Ethernet. 7.4.2.3.5 Evolution Towards CE The evolution towards CE is shown in Figure 7.18. The CE standardization process started in early 2000 with the completion of RFC 3031 MPLS in January 2001. The PBB-TE was standardized in 2009 while MPLS-TP specifications are expected in 2010/2011. 7.4.2.3.6 Carrier Ethernet Technologies The two dominant technologies for Carrier Ethernet are MPLS-TP and PBB-TE. MPLS-TP is a joint standardization effort between the ITU-T and the IETF; as state