Network Card User Manual

CHAPTER
20-1
Ethernet Card Software Feature and Configuration Guide, R7.2
January 2009
20
POS on ONS Ethernet Cards
This chapter describes packet-over-SONET/SDH (POS) and its implementation on ONS Ethernet cards.
This chapter contains the following major sections:
• POS Overview, page 20-1
• POS Interoperability, page 20-2
• POS Encapsulation Types, page 20-4
• POS Framing Modes, page 20-7
• POS Characteristics of Specific ONS Ethernet Cards, page 20-7
• Ethernet Clocking Versus SONET/SDH Clocking, page 20-11
POS Overview
Unlike Asynchronous Transfer Mode (ATM) and Frame Relay, Ethernet was not originally designed for
interfacing with SONET/SDH. Ethernet data packets need to be framed and encapsulated into a
SONET/SDH frame for transport across the SONET/SDH network. This framing and encapsulation
process is known as POS.