Circuit Emulation Parameters; Circuit Emulation Modes; Absolute Mode Option; Payload Size - Alcatel-Lucent 7750 SR Manual

Circuit Emulation Parameters

Circuit Emulation Modes

All channels on the CES CMA/MDA are supported as circuits to be emulated across the packet
network. Structure aware mode is supported for n*64 kbps channel groups in DS1 and E1 carriers.
Fragmentation is not supported for circuit emulation packets (structured or unstructured).
For DS1 and E1 unstructured circuits, the framing can be set to unframed. When channel group 1
is created on an unframed DS1 or E1, it is automatically configured to contain all 24 or 32
channels respectively.
N*64 kbps circuit emulation supports basic and Channel Associated Signaling (CAS) options for
timeslots 1-31 (channels 2-32) on E1 carriers and channels 1-24 on DS1 carriers. CAS in-band is
supported, therefore no separate pseudowire support for CAS is provided. CAS option can be
enabled or disabled for all channel groups on a given DS1 or E1. If CAS operation is enabled,
timeslot 16 (channel 17) cannot be included in the channel group on E1 carriers. CCS operation is
not supported.

Absolute Mode Option

For all circuit emulation channels except those with differential clock sources, RTP headers in
absolute mode can be optionally enabled (off by default). For circuit emulation channels which
use differential clock sources, this configuration is blocked. All channel groups on a given DS1 or
E1 can be configured for the same mode of operation.
When enabled for absolute mode operation, an RTP header will be inserted. On transmit, the CES
IWF will insert an incrementing (by 1 for each packet) timestamp into the packets. All other fields
will be set to zero. The RTP header will be ignored on receipt. This mode is enabled for
interoperability purposes only for devices which require an RTP header to be present.

Payload Size

For DS3, E3, DS1 and E1 circuit emulation, the payload size can be configurable in number of
octets. The default values for this parameter are shown in
be set to a multiple of 32 octets and minimally be 64 octets.
7750 SR OS Services Guide
Virtual Leased Line Services
Table 7. Unstructured payload sizes can
Page 189