Configuring Cem Parameters - Cisco ASR 1000 Series Software Configuration Manual

Configuring the Circuit Emulation over Packet Shared Port Adapter

Configuring CEM Parameters

The following sections describe the parameters you can configure for CEM circuits.
Note The CEM parameters at the local and remote ends of a CEM circuit must match; otherwise, the pseudowire
between the local and remote PE routers will not come up.
Configuring Payload Size (Optional)
To specify the number of bytes encapsulated into a single IP packet, use the pay-load size command. The
size argument specifies the number of bytes in the payload of each packet. The range is from 32 to 1313 bytes.
Default payload sizes for an unstructured CEM channel are as follows:
• E1 = 248 bytes
• T1 = 192 bytes
• DS0 = 32 bytes
• T3/E3 = 1024 bytes
Default payload sizes for a structured CEM channel depend on the number of time slots that constitute the
channel. Payload size (L in bytes), number of time slots (N), and packetization delay (D in milliseconds) have
the following relationship: L = 8*N*D. The default payload size is selected in such a way that the packetization
delay is always 1 millisecond. For example, a structured CEM channel of 16xDS0 has a default payload size
of 128 bytes.
The payload size must be an integer of the multiple of the number of time slots for structured CEM channels.
Setting the Dejitter Buffer Size
To specify the size of the dejitter buffer used to compensate for the network filter, use the dejitter-buffer
size command. The configured dejitter buffer size is converted from milliseconds to packets and rounded up
to the next integral number of packets. Use the size argument to specify the size of the buffer, in milliseconds.
The range is from 1 to 500 ms; the default is 5 ms.
Setting the Idle Pattern (Optional)
To specify the idle pattern, use the [no] idle-pattern pattern1 command. The payload of each lost CESoPSN
data packet must be replaced with the equivalent amount of the replacement data. The range for pattern is
from 0x0 to 0xFF; the default idle pattern is 0xFF.
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Cisco ASR 1000 Series Aggregation Services Routers SIP and SPA Software Configuration Guide, Cisco IOS XE
Configuring CEM Parameters
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