E-Cpos - HP HSR6800 Configuration Manual

Tributary unit (TU) and tributary unit group (TUG)—TU is the information structure that provides
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adaptation between higher-order paths and lower-order paths. TUG is a set of one or more TUs
whose locations are fixed in higher-order VC payload.
• Administrative unit (AU) and administrative unit group (AUG)—AU is the information structure that
provides adaptation between the higher-order path layer and the multiplex section layer. AUG is a
set of one or more AUs whose locations are fixed in the STM-N payload.
Optical carrier (OC)—OC is a series of physical protocols (including OC- 1 , OC-3, and so on)
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defined for optical transmission over an SONET network. The number in an OC level corresponds
to a rate for STS frames. The base rate is 51.84 Mbps (OC- 1 ), the rate of OC-3 is 155.52 Mbps, and
so on.

E-CPOS

The low-speed tributary signals multiplexed to form an SDH signal are called channels. A channelized
POS (CPOS) interface makes full use of SDH to provide precise bandwidth division, reduce the number
of low-speed physical interfaces on devices, enhance their aggregation capacity, and improve the
access capacity of dedicated lines.
The basic functions of enhanced CPOS (E-CPOS) interfaces and CPOS interfaces are the same but their
port rate hierarchies and channelization levels are different. For more information, see
operating mode of an E-CPOS
Channelized and unchannelized
A channelized POS interface uses the low-speed tributary signals of STM-N to transmit multiple
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streams of data independent of one another over an optical fiber. Each data stream shares
separate bandwidth and has its own start point, end point, and monitoring policy. They are called
channels.
An unchannelized POS interface uses all STM-N signals to transmit a stream of data over an optical
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fiber. The transmitted data has the same identifier, start point, and end point, and is regulated by
the same monitoring policy.
When multiple streams of low-speed signals are to be transmitted, channelization can make better use of
bandwidth. When a single high-speed stream of data is to be transmitted, the unchannelized mode is
recommended.
Operating modes of E-CPOS interfaces
An E-CPOS interface can operate in channelized mode or concatenated mode:
In channelized mode, a higher-order STM-N frame is regarded as being formed by four lower-order
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STM-N frames through time-division multiplexing. A higher-order STM-N frame will be
demultiplexed into multiple lower-order STM-N frames for processing.
In concatenated mode, STM-N frames are processed without being demultiplexed.
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E-CPOS interface application scenario
E-CPOS is used to enhance the capability of a device in low-speed access aggregation. STM- 1 E-CPOS
is especially suitable for aggregating E3/T3 channels. As shown in
agencies and enterprises use low-end and mid-range routers to access transmission networks through
E3/T3 leased lines. Users who require bandwidth between E3 and T3, for a data center for example,
lease multiple E3/T3 lines. The bandwidth of all these users is aggregated to one or more CPOS
interfaces through the transmission network, and then connected to a high-end router where the low-end
routers are uniquely identified by timeslots.
interface/channel."
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