18
Installation PTN-4-2/4WEM
Release 01 02/2018
Table 8
Estimated Delay Formulas
Delay
No Hitless Switching
Hitless Switching
P
TDMFramesPerPacket * 125
Path Delay
measured by HiProvision
DP
(JitterBufferSize – P) / 2
DPh
0
2P + MaxNetwPathDel 1087
Total
P + Path Delay + DP + DPh
3.3.4
Estimated Delay Examples
Find some example values below. Fill them out in the formulas to find the estimated total
delay:
TDMFramesPerPacket = 10
Pathdelay (measured by HiProvision) = 500 µs
JitterBufferSize = 4000 µs
MaxNetwPathDelayDiff = 340 µs
Table 9
Estimated Delay (µs) Examples
Delay
No Hitless Switching
Hitless Switching
P
10
* 125 = 1250
Path Delay
500
DP
(
4000
–
1250) / 2 = 1375
DPh
0
2*1250 +
340
+ 1087 = 3927
Total
1250 + 500 + 1375 + 0 =
3125 µs
1250 + 500 + 1375 + 3927 =
7052 µs
3.4
Tuning CES = Tuning TDM Frames/Packet
Tuning the CES is mainly done by tuning the TDM Frames/Packet parameter. Tuning this
parameter is a trade-off between bandwidth and delay. The more bandwidth is consumed
the less the resulting network delay and vice versa. This tuning is application dependent.
Check out whether bandwidth or delay is critical for an application or network. Based on
these findings, bandwidth and delay parameters can be tuned.
Some examples according the information in §3.2 and §3.3:
if bandwidth is not a problem, and a small delay is wanted → 1-6 TDM frames/packet;
if less bandwidth is required and delay is not important → at least 8 TDM frames/packet;
if less bandwidth and a small delay are wanted → 8 .. 10 TDM frames/packet.
