4-8
Cisco ONS 15454 SONET/SDH ML-Series Multilayer Ethernet Card Software Feature and Configuration Guide, R4.0
78-15224-02
Chapter 4 Configuring Interfaces
POS on the ML-Series card
POS on the ML-Series card
Packet over SONET/SDH (POS) is a high-speed method of transporting IP traffic between two points.
This technology combines the Point-to-Point Protocol (PPP) with SONET and Synchronous Digital
Hierarchy (SDH) interfaces. SONET is an octet-synchronous multiplex scheme defined by the American
National Standards Institute (ANSI) standard (T1.105.1988) for optical digital transmission, and SDH
is the European Telecommunications Standards Institute (ETSI) equivalent.
ML-Series SONET/SDH transmission rates
SONET transmission rates are integral multiples of 51.840 Mbps. The transmission multiples in
Table 4-1 are supported.
SONET Frame Fundamentals
SONET is a Layer 1 protocol that uses a layered architecture. Figure 4-1 on page 4-9 shows SONET’s
three layers: section, line, and path. The section overhead (SOH) and line overhead (LOH) form the
transport overhead (TOH), while the path overhead (POH) and actual payload (referred to as payload
capacity) form the synchronous payload envelope (SPE). Each layer adds a number of overhead bytes to
the SONET frame.
Table 4-1 Transmission Multiples Supported by ML-Series Cards
Topology Supported Sizes
Circuits terminated by two ML-Series cards STS-1, STS-3c, STS-6c, STS-9c, STS-12c, and STS-24c
(SONET) or VC4, VC4-2c, VC4-3c, VC4-4c, and
VC4-8c (SDH)
Circuits terminated by G-Series card and
ML-Series card
STS-1, STS-3c, STS-6c, STS-9c, STS-12c (SONET) or
VC4, VC4-2c, VC4-3c, VC4-4c, and VC4-8c (SDH)
Circuits terminated by ML-Series card and
External POS device
STS-3c and STS-12c (SONET) or VC4-2c and VC4-3c
(SDH)
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