XENPAK Modules: the XENPAK is an early 10Gbps pluggable optical transceiver developed based on the XENPAK Multi-source Agreement (MSA) which was instigated by Agilent Technologies and Agere Systems. XENPAK modules dimensions are 121 x 36 x 18 mm (the biggest in 10G fiber transceiver modules) weigh approximately 200-300g and include a dual SC fiber interface. A wide range of XENPAK modules are available, operating with copper line, multimode optical fiber line and single mode optical fiber line. A typical copper XENPAK module (such as Cisco’s XENPAK-10GB-CX4) max span is 15 meters. Some examples of multimode XENPAK modules include Cisco’s XENPAK-10GB-LX4, XENPAK-10GB-LRM and XENPAK-10GB-SR, these modules use both 50/125 and 62.5/125 micron multimode fiber and their working distance max is up to 300 meters. Typical single mode XENPAK modules are Cisco’s XENPAK-10GB-LR, XENPAK-10GB-LR, XENPAK-10GB-ER, XENPAK-10GB-ZR; these transceivers operate with 9/125 micron single mode optical fiber and their working distance range from 10km to 80km max.