Bandwidth Reservation for Multicast Traffic

Unanswered Question
Apr 26th, 2010

Hi all,

I have a scenario where I have around 45Meg of multicast traffic going from SW1 to SW3 across the OC-3 link. This OC-3 link is shared with Data traffic also. The network scenario is like this:

Multicast Traffic --->Cisco 3750{Gig1/0/2}-------(OC-3)--------{Gig1/0/1}Cisco 3750{Gig1/0/2}---------{Gig1/0/1}Cisco 3750{Gig1/0/2}------ Multicast Receiver

                                     SW1                                                            SW2                                                SW3

Now, during congestion of OC-3 link, i need to gurantee 45Meg of multicast traffic across the OC-3. Its ok to drop Data traffic during congestion.

How can i achieve this? Any suggestion is appreciated.

I have this problem too.
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Giuseppe Larosa Tue, 04/27/2010 - 02:10

Hello DMalla,

if you had routers you could use modular QoS and CBWFQ to provide resources to multicast traffic

you have C3750 so all you have is SRR on C3750 ports.

In this case you can dedicate a queue to multicast traffic but you need to mark multicast traffic on input interfaces

input marking is supported.

You must ensure that data traffic has never the same settings in order to have unicast data traffic in another queue.

then on outbound you need to combine commands to perform

a) shaping to 155 Mbps outbound

srr-queue bandwidth limit weight1


configuring the SRR queues and Weighted Tail Drop thresholds to provide resources to the multicast traffic class

Here, you configure weights so what counts are the ratio between these weights.


Hope to help



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