ZL50120 Zarlink, ZL50120 Datasheet - Page 53

• Manufacturer Part Number: ZL50120
• Description: 32 / 64 / 128 Channel CESoP Processors
• Manufacturer: Zarlink

6.4.1.1
Packets are assembled sequentially, with each channel placed into the packet as it arrives at the TDM
Interface. A fixed order of channels is maintained (see Figure 18), with channel 0 placed before channel 1,
which is placed before channel 2. It is this order that allows the packet to be correctly disassembled at the far
end. A context must contain only unique channel numbers. As such a context that contains the same channel
from different streams, for example channel 1 from stream 2 and channel 1 from stream 3, would not be
permitted.
Each packet contains one or more frames of TDM data, in sequential order. This groups the selected channels
for the first frame, followed by the same set of channels for the subsequent frame, and so on.
6.4.2
In unstructured mode, the payload is not split by defined frames or timeslots, so the packet consists of a continuous
stream of data. Each packet consists of a number of octets, as shown in Figure 19. The number of octets in a
packet need not be an integer number of frames. A typical value for N may be 192, as defined in the IETF PWE3
standard."
For example, consider mapping the unstructured data of a 25 timeslot DS0 stream. The data for each T1 frame
would normally consist of 193 bits, 192 data bits and 1 framing bit. If the payload consists of 24 octets it will be 1 bit
short of a complete frames worth of data, if the payload consists of 25 octets it will be 7 bits over a complete frames
worth of data. NOTE: No alignment of the octets with the T1 framing structure can be assumed.
N octets of data from unstructured stream
NOTE: No frame or channel alignment
Unstructured Payload Operation
Payload Order
S tre a m 0
S tre a m 1
S tre a m 2
S tre a m 3
Figure 19 - ZL50115/16/17/18/19/20 Packet Format - Unstructured Mode
C h a n n e l 0
C h a n n e l 0
C h a n n e l 0
C h a n n e l 0
Figure 18 - Channel Order for Packet Formation
Header
ZL50115/16/17/18/19/20
C h a n n e l 1
C h a n n e l 1
C h a n n e l 1
C h a n n e l 1
(if required to meet minimum payload size)
Zarlink Semiconductor Inc.
(added by Packet Transmit)
(added by Protocol Engine)
Ethernet Header
Network Layers
Static Padding
C h a n n e l 2
C h a n n e l 2
C h a n n e l 2
C h a n n e l 2
Ethernet FCS
C h a n n e l A s se m b ly O rd e r
Upper layers
53
Octet N
Octet 1
Octet 2
may include VLAN tagging
e.g. IPv4, IPv6, MPLS
e.g. UDP, L2TP, RTP,
TDM Payload
(constructed by Payload Assembler)
46 to 1500 bytes
may also be placed in the
packet header
CESoPSN, SAToP
C h a n n e l 3 1
C h a n n e l 3 1
C h a n n e l 3 1
C h a n n e l 3 1
Data Sheet