Significant dense Packet over SONET (POS) deployments exist despite the overwhelming industry trend toward Ethernet. Operators are looking for POS-like operations, administration, and maintenance (OAM) functions at Ethernet price points with technologies such as OTN G.709 encapsulation. Some operators have traditional transponder systems that can operate only in OC-768 and OTU-3 modes. In addition, bandwidth growth is leading all markets, including data center operators, to move to 40 Gigabit Ethernet in the aggregation layer to handle growth in the data center. The Cisco CRS 4-Port 40GE LAN/OTN Interface Module addresses both these needs. The 4-port 40GE module in OTN mode with multirate serial C Form-Factor Pluggable (CFP) Fiber with Scrambled Encoding (FR) optics addresses the requirements for POS such as OAM functions at Ethernet prices, and the 4-port 40GE module in LAN mode with CFP Long-Reach (LR) or CFP Short-Reach (SR) optics provides a dense 40 Gigabit Ethernet solution for data centers and 10 Gigabit Ethernet aggregation.