Specifications

68 IBM Voice Over Frame Relay Perform Guide
Figure 37. The Problem of Tc=1 sec with VOFR and Tc=45 msec with VOFR
• Tc = 45 msec
• CIR = 16 kbps
• Bc = 720 bits
•Be=0
• Line speed = 64 kbps
With this setup voice frames are generated at very short intervals like 45 ms (for
example, with frame packing = 3) and this works fine without discarding any
frames.
See “Performance Tuning, and Monitoring” on page 157 in detail.
4.1.7 Maximum Information Rate (MIR)
The maximum information rate is the maximum data rate at which the router
transmits for a VC. If the CIR monitoring feature is enabled and CIR and Bc are
nonzero, the maximum information rate is calculated using CIR, Bc, and Be as
follows:
(Bc + Be) per Tc interval
If the CIR monitoring feature is enabled and CIR and Bc are configured equal to
0, the maximum information rate is equal to the excess burst size (Be) per
second.
If the CIR monitoring feature is not enabled the maximum information rate is
equal to the line speed.
4.1.8 Minimum Information Rate
The minimum information rate (IR) is the minimum data rate for a VC that the
router throttles down to when it is notified of congestion. You set the minimum IR
as a percentage of CIR using the
set ir-adjustment configuration command. It
can be dynamically changed using the
set ir-adjustment console command. If
you configure CIR equal to 0, the minimum IR is 1500 bps.
0 250
1000
64000
bit
Discard Voice frame 750msec
Voice
Voice &
Data
msec
0 250
1000
64000
bit
Discard Voice frame 750msec
Every 45msec Voice Frame generated(Frame packing=3)
Voice
Voice &
Data
msec
64000
bit
45 18013590
0ms
Every 45msec Voice Frame generated(Frame packing=3)
Voice
Voice&
Data