3Com 3C63311 Reference Guide - Page 18

6 CHAPTER 1: SYSTEM DESCRIPTION The following optional modules are available for use with the PathBuilder S310: n The two-port CBR module services traffic generated by your existing PBXs, channels, T1/E1 multiplexers, CSU/DSUs, and video conferencing devices. The CBR module consists of one V.35/RS-449 and one T1-DSX or E1 interface, which support both structured and unstructured services, in accordance with the ATM Forum's Circuit Emulation Service (CES) specifications. The CBR module provides a smooth migration from legacy CBR service (PBX/voice/video) to ATM service. It also supports all relevant ATM and T1/E1 standards, ensuring easy integration of existing equipment into new ATM networks. n The one-port Voice Compression module (VCM) is similar in function to the CBR module, but it employs compression algorithms that allow more voice calls to be placed through the same bandwidth. The VCM's T1-DSX/E1 interface connects to a PBX trunk, which may use CAS or CCS signaling. Its 24/31 DSO channels can carry individual voice, fax, modem, or data connections. You can also bundle multiple DSOs to provide connections for high-rate applications such as video conference or multiple-link PPP. For CCS, a DSO is used as an ISDN D-channel for carrying signal messages. Figure 2 shows the PathBuilder S310, with the optional CBR module installed in expansion slot 7 and the Voice Compression module in slot 8. Figure 2 PathBuilder S310 WAN Access Switch Video/Audio Codec PBX PBX V.35/ RS-449/ RS-530/ X.21 RS-366 T1-DSX/E1 T1-DSX/E1 RS-232 10BASE-T NMS Console LAN V.35/ RS-449/ RS-530/ X.21 Router T1/E1