RAD Data comm TDMoIP Gateway IPmux-16 - Manual (Page 21)

IPmux-16 Installation and Operation Manual Chapter 1 Introduction
Functional Description 1-13
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
bytes/frame Frame
Length
(bytes) Overhead
(bytes) Overhead
(%) Packets
(per
second) Throughput
(Mbps)
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