RAD Data comm IPmux-16 Ethernet Throughput Unframed E1, Frame Overhead Packets Throughput

IPmux-16Installation and Operation Manual Chapter 1 Introduction

Ethernet Throughput

Configuring the TDM bytes per frame (TDM bytes/frame) parameter, per bundle configuration, can reduce Ethernet throughput (bandwidth or traffic travelling through the Ethernet). This parameter controls the number of TDM bytes encapsulated in one frame. The TDM bytes/frame parameter can be configured to nX48 bytes where n is an integer between 1 and 8. Configuring TDM bytes/frame to a higher value reduces the IP/Ethernet overhead segment of the total packet and thus can significantly reduce the total Ethernet throughput.

On the other hand, packetization delay and intrinsic packet delay variation (PDVT) are increased and this contributes to a higher end-to-end delay. This effect can be small and negligible when a full E1 (or many timeslots) are transferred but can be very significant when few E1/T1 timeslots are transferred. In this case, the packetization delay and the intrinsic PDV when configuring a large value of TDM bytes / frame can be very large and may exceed the maximum PDVT (jitter) buffer on the receiving end. The tables below show the throughput as a function of the TDM bytes/frame configuration for a full E1 and a full T1.

Table 1-3. Ethernet Throughput – Unframed E1

TDM	Frame	Overhead	Overhead	Packets	Throughput
bytes/frame	Length	(bytes)	(%)	(per	(Mbps)
	(bytes)			second)
48	94	46	96	5447	4.1
96	142	46	48	2724	3.1
144	190	46	32	1816	2.76
192	238	46	24	1362	2.6
240	286	46	19	1089	2.5
288	334	46	16	908	2.43
336	382	46	14	778	2.38
384	430	46	12	681	2.34

Functional Description 1-13