The Packet-Over-SONET OC3 port adapter PA-POS-OC3MM provides OC-3 physical layer interface for packet-based traffic. This OC-3 interface is fully compatible with SONET and Synchronous Digital Hierarchy (SDH) network facilities and is compliant with RFC 1619, "PPP over SONET/SDH, " and RFC 1662, "PPP in HDLC-like Framing." The Packet-Over-SONET specification is primarily concerned with the use of the PPP encapsulation over SONET/SDH links.The PA-POS-OC3 interface provides a direct connection between the supported router or switch platform and external networks. You must use the appropriate optical fiber cables to connect the PA-POS-OC3 with an external OC-3 network.