Cisco Systems IPMUX-1E Pdvt Jitter Buffer, Pdvt Buffer Effect on Delay, Should be 6 ms

IPmux-1/1EInstallation and Operation Manual Chapter 1 Introduction

Packets Leaving IPmux-1 t

Packets Arriving

t

PDV

Figure 1-17. Packet Delay Variation

PDVT (Jitter) Buffer

IPmux-1 is equipped with a Packet DVT (Delay Variation Tolerance) buffer. The PDVT buffer or jitter buffer is filled by the incoming IP packets and emptied out to fill the TDM stream. The buffer begins to empty out only after it is half full in order to compensate for packet starvation from the Ethernet side. The time it takes for half of the buffer to empty out is the maximum DVT time. Delay Variation Tolerance is configurable. The PDVT (jitter) buffer is designed to compensate for packet delay variation caused by the network + intrinsic PDV.

It supports a delay variation of up to 300 ms for E1 or T1 in static or dynamic CAS modes, and up to 127 ms in CESoIP mode.

PDVT Buffer Effect on Delay

The PDVT buffer is on the TDM path; it adds to the total end-to-end delay (see delay calculation, below).

Intrinsic PDV in Static Mode

If TDM bytes/frame is greater than 48, there is an intrinsic delay variation (intrinsic PDV). The intrinsic PDV introduced by the module is a function of n>1 in TDM bytes/frame configuration as follows:

I.PDV (ms) = [(n-1) x 1000) / (frames per second ⋅ n]

where n =	Configured TDM bytes/frame	(n = 1 to 8).
	48
To configure jitter buffer depth:

The estimated or measured PDV introduced by the network + intrinsic PDV (if it exists) introduced by the module as a result of configuring the

TDM bytes / frame > 48.

Note	For a bundle that contains a few timeslots (i.e. 1 to 3) the minimal jitter buffer
	should be 6 ms.

Functional Description 1-19