Specifications

Chapter 1 Introduction Installation and Operation Manual
1-12 Functional Description MPW-1 MP-4100 Ver. 2.0
configured as the destination (outbound) label at the other pseudowire endpoint,
and vice versa.
Each pseudowire is handled in accordance with the user-configured PSN
parameters (see the
PSN Configuration Parameters section), considering the
user-selected pseudowire parameters, and the framing and signaling mode of the
associated internal DS1 port. The processing details for each pseudowire protocol
are presented below.
TDMoPSN Processing
The main functions performed by the packet processor when using the TDMoPSN
mode are as follows:
• In the transmit-to-network direction:
 Processes the data stream received through the internal DS1 port to
generate pseudowires, as specified by the user. When using a framed
mode, the user can specify the timeslots to be transported end-to-end.
To prepare a pseudowire, the packet processor extracts segments from
the continuous data stream for insertion into the pseudowire payload
section.
The size of the pseudowire payload section is specified by the user
(
n × 48 bytes, where n is 1 to 30):
 When operating in a framed mode, the slices are formed by collecting
the appropriate timeslots from consecutive frames until the TDM
payload section of the packet is filled. Timeslot 0 is never included;
timeslot 16 is processed in accordance with the signaling mode.
 When operating in the unframed mode, the slices are formed by
collecting consecutive bytes from the received DS1 stream until the
TDM payload section of the packet is filled.
 Adds the overhead necessary to transmit each slice over the packet
switched network (either UDP/IP or MPLS/ETH), and builds TDMoIP,
respectively TDMoMPLS, packets for transmission to the desired
destination. The resulting packets are encapsulated as TDMoPSN over
Ethernet, and then sent to the Ethernet switching subsystem of the
module.
 When signaling transport is enabled and the pseudowire timeslots are
defined as voice timeslots, the signaling information associated with the
timeslots transported by the pseudowire is also inserted in the packet.
• In the receive-from-network direction:
 The TDMoPSN packets retrieved from the received Ethernet frames are
stored in a packet buffer. Each pseudowire has its own buffer.
The function of this buffer is to enable the packet processor to read the
received packets at the rate of the original data stream of each
pseudowire, and thus eliminate jitter in their arrival times. Therefore, this
buffer is called
jitter buffer .