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JunosE 11.3.x Multicast Routing Configuration Guide
152
NOTE: When the mroute is first installed in the FC (at t = 0), R
undetermined. For multicast admission control no joins are admitted until
the first bandwidth measurement is computed (that is, for admission control,
R
is considered to be infinite). Similarly, no QoS adjustment occurs until the
0
first bandwidth measurement is computed (that is, for QoS adjustment, R
is considered to be zero [0]).
Using the earlier graph as a reference, the first bandwidth rate (R1
and the bytes received values are subtracted and divided by the time period T
the average rate. This process is repeated every sampling interval, T
R2, R3, and so on.
The first two sampling interval calculations would look like the following:
R
= (N
- N
)/5
1
5
0
R
= (N
- N
)/5
2
#+5
#
The router maintains a history of bandwidth measurements (H) for each mroute, up to
a maximum of M measurements. The actual rate, R, reported to the SRP is the maximum
rate measured in those H samples.
In order to minimize the IC to SRP traffic generated by the rate measurements, the IC
reports a bandwidth change only when a newly computed rate (R#) differs from the
current rate by a specified threshold. When R
to R
. A rate update occurs whenever a newly calculated rate (R) differs from R
1
least a threshold value (specified as a percentage, P) of the measured peak bandwidth.
This calculation would look like the following:
R = Rt, if and only if the absolute value of (R - Rt) > P * R.
The values assigned to variables associated with this algorithm are as shown in Table 9
on page 152.
Table 9: Adaptive Mode Algorithm Values
Variable
Value
Units
T1
5
Seconds
T2
0
Seconds
H
12
Samples
M
12
Samples
is computed at time t = 5 seconds, R is set
s
Description
Sampling period; the time in which a sample is taken
Sampling interval; zero (0) seconds indicates continuous
sampling
Number of history samples over which to compute
measurement
Maximum number of samples maintained in history
Copyright © 2010, Juniper Networks, Inc.
is
0
0
) and at time t
(N
)
0
5
5
to yield
1
, to yield rates R1,
2
by at
1
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