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Download throttle on a 3120

Hi all,

Believe it or not, I'd like to throttle download speed on a 3120 router!

Here's the issue... This 3120 is the "cental" router of a SMB. We're installing a new IP PBX connected to a SIP provider. They're connected to a 100/100 mbits fiber Internet connection.

eth 0/1 : WAN access - Fiber 100/100 mbits connection

int vlan 1 : Customer' LAN

int vlan 11 : VoIP vlan

int vlan 74 : Interface to a SIP Provider' SBC

Internet connection is SO fast, the small 3120 CPU often reach 100% (NAT, stateful firewall, etc.)... I have routing issues/delay/jitter between VoIP vlan and SBC vlan. This is very bad for voice quality. To me, this is not a QoS issue, but a CPU issue.

I mentioned to the customer that a 3120 may be a little too "small" for him. He told me he don't need 100 mbits of Internet... 30 would be enough for his needs. ISP told me they can't throttle bandwidth on their side.

This is 100/100 or nothing.

To my best knowledge "traffic-shape rate" is related to upload bandwitdh.

So, Is there a way to throttle download bandwitdh?

Thank you for your help!

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Re: Download throttle on a 3120


Thank you for asking this question in the support community.  From the information you've provided, it sounds like you may have the incorrect NetVanta unit for this application.  My recommendation would be to contact ADTRAN applications engineers for assistance with selection of products for your network design and application.  However, in the meantime, you can use the traffic-shape rate <value> command to limit the output bandwidth (and due to TCP windowing, it should reduce the input as well).  Also, verify that the Quality of Service (QoS) is setup properly for the VoIP.  Here is the Configuring QOS in AOS for reference.

Do not hesitate to reply to this post with any additional information or questions.  I will be happy to assist you in any way I can.


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Re: Download throttle on a 3120


I went ahead and flagged this post as "Assumed Answered." If any of the responses on this thread assisted you, please mark them as Correct or Helpful as the case may be with the applicable buttons. This will make them visible and help other members of the community find solutions more easily. If you still need assistance, we would be more than happy to continue working with you on this - just let us know in a reply.