RAD Data comm IPmux-11 operation manual Data, Packet Delay Variation

Installation and Operation Manual Chapter 1 Introduction

Table 1-4. TDMoMPLS Frame Structure

	Field Length (Bytes)	Field
	7	Preamble
ETH	1	SFD
	6	Destination MAC Address
Layer
	6	Source MAC Address
LLC	2	Type
Layer	20	Outer label
	3	EXP
	1	Stacking bit
MPLS	8	TTL
Layer	20	Inner label
	3	EXP
	1	Stacking bit
Data	8	TTL
Layer ...		Payload
ETH	4	CRC
Layer

Packet Delay Variation

Note: IEEE 802.1p&Q VLAN Tagging (additional 4 bytes if enabled)

The inner label field is used to transfer a destination bundle number.

Packets are transmitted at set intervals. Packet Delay Variation is the maximum deviation from the nominal time the packets are expected to arrive at the far end device. IPmux-11 has a buffer that compensates for the deviation from the expected packet arrival time to prevent IPmux-11 buffers from emptying out or overflowing.

Packet Delay Variation is an important network parameter. Large PDV (exceeding the jitter buffer configuration) will cause receive buffer underflows and errors at the TDM level (see Figure 1-9).

To compensate for large PDV, configure the PDVT (jitter) buffer to a higher value.

Packets Leaving IPmux-11

t

Packets Arriving

PDV

Figure 1-9. Packet Delay Variation

t

IPmux-11 Ver. 2.00 Functional Description 1-11