Juniper JUNOSE 11.1.X MULTICAST ROUTING, Руководство по настройке

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host1(config-route-map)# set admission-bandwidth adaptive
host1(config-route-map)# set qos-bandwidth adaptive
host1(config-route-map)# end
In this example, any stream with an (S,G) that matches the sdtv access list performs
adaptive bandwidth detection for admission control and QoS adjustment.
A rate measurement mechanism runs on the ingress line card that polls the forwarding
controller (FC) to obtain statistics for each mroute. This mechanism then reports the
rate measurement to the SRP to update the bandwidth map. By computing the
average bandwidth over a relatively short sampling period (T1; 5 seconds), the
measurement approximates the peak bandwidth of the multicast stream.
As an example, assume that a new mroute (S1, G1) is added to the interface controller
(IC) at time t0.
Figure 1: Example of Adaptive IPv4 Multicast Bandwidth Detection
To calculate the measured bandwidth of a stream, the router uses the following
equation:
R = (N
t+5
– N
t
) / 5
Where
R = Calculated bandwidth of the stream during each sampling interval
N
t
= Bytes measured at the start of each sampling period (t seconds)
N
t+5
= Bytes measured at the end of each sampling period (t+5 seconds)
NOTE: When the mroute is first installed in the FC (at t = 0), R
0
is undetermined.
For multicast admission control no joins are admitted until the first bandwidth
measurement is computed (that is, for admission control, R0 is considered to be
infinite). Similarly, no QoS adjustment occurs until the first bandwidth measurement
is computed (that is, for QoS adjustment, R0 is considered to be zero [0]).
Using the previous graph as a reference, the first bandwidth rate (R1
0
) and at time
t
5
(N
5
) and the bytes received values are subtracted and divided by the sampling
12 ■
Defining a Multicast Bandwidth Map
JUNOSe 11.1.x Multicast Routing Configuration Guide