Specifications

Design Consideration for a VoFR Network 13

Figure 8. 2212 HQ Information Rate and Time

Table 6 gives the fragmentation size recommendations from Nuera.

Table 6. Nuera Recommendations for Line Speed and Fragmentation Size

2.5.1 The Rule of Thumb for Defining Tc Value

The rule of thumb for defining the Tc value is as follows:

Tc = Number of Frame packing times the interval of voice frame generation

Table 7. Example of Rule of Thumb to Define Tc Value

Line Speed Fragmentation size

64 kbps 64 bytes

128 kbps 128 bytes

256 kbps 256 bytes

512 kbps 512 bytes

Evocator Frame packing Tc Value

E-CELP 1 30 (Minimum Tc is 30)

E-CELP 2 30

E-CELP 3 45

E-CELP 4 60

E-CELP 5 75

1.5Mbps

64kbps

CIR=16kbps

Time

Information Rate

CIR monitor

enable

CIR monitor

disable

CIR=16

12%inclease

CIR monitor : enable

MIR=Line Speed=1.5bps

CIR monitor: disable

BECN=1

25% decrease

25% of CIR=4kbps

2212 HQ

IBM 2212

2212 HQ Information Rate and Time

BECN=0

MIR=(Bc+Be)/Tc=64Kbps