Adaptive Frame Relay Traffic Shapping

Unanswered Question
Mar 31st, 2009

If I have 10 locations having a single T1 which are PVC's and two locations which are DS3's PVC and at 10Mb. By using Adaptive Frame Relay Traffic Shapping, would I be able to, when congestion is high between the two sites with the 10Mb link, reallocate some bandwidth from the other sites to increase the capacity to over 10 MB?

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Mohamed Sobair Tue, 03/31/2009 - 12:43


Its been very long time, I have had almost similar type of question on my previous exam but in different way.

The Frame-relay Adaptive shaping command allows DTEs to respond to BECN and FECN messages sets at the frame-relay header. When the link is congested and becn bit set, the speed is decreased to the CIR value configured, therefore, it would allow dor dynamic bandwidth relocation between sites.



Mohamed Sobair Tue, 03/31/2009 - 13:06

I didnt test it, but theoratically it should if all FR DTEs enabled for(Adaptive Shaping).



mattesong Tue, 03/31/2009 - 13:07

okay thank you. it would be fesible to assume we could get greater than a 10 MB throughput between site A and site B by reallocating some bandwidth from the other sites?

Mohamed Sobair Tue, 03/31/2009 - 13:32

As I said, I didnt test it, I've been merely pointing at what the (Adaptive shaping) command does in Frame-relay.

theoratically , its fesible to assume that.



Joseph W. Doherty Tue, 03/31/2009 - 17:17

If you have asymetrical bandwidths, if supported, suggest you shape larger to conform with slower link's capacity. E.g. on DS3 or 10 Mbps, shape outbound PVC to T1, it that's what's on the other side of PVC.

As to using BECNs, you first need, I believe, to echo the FECNs, and then you can dynamically "safely" use bandwidth between CIR and link capacity.


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