Can DE bit be used for slowing down the traffic flow rate?

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Nov 10th, 2008
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Hi Folks,

I have a doubt in DE bit in frame-relay cloud. Normally we used to set this bit on the packets which should be dropped in SP cloud before any other data packets of the client.

We use FECN,BECN as well as ECN with WRED to convey the message to remote router to slow down the traffic rate.

Is there any method that remote router sense the increase DE bit and slow down teh application flow rate?

Thanks for replying in advance.


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Joseph W. Doherty Mon, 11/10/2008 - 11:20
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DE bit, I believe, is unique to frame-relay, although recall ATM's CLP bit serves a similar purpose. Neither provides direct feedback for flow control purposes, although dropping the frame/cell/packet may. Either might be explicity set (I believe on some equipment) to indicate lower priority traffic that's intentionally being sent at a rate higher than what's contracted with the cloud vendor.

FECN/BECN can be used on the router with an adaptive rate shaper.

ECN is a host-to-host flow management scheme which isn't really intended to set flow rates on routers. Many host stacks, I believe, don't support it.


If you're having an issue with some heavy bandwidth flows adversely impacting other light bandwidth flows on frame-relay, you might be better served with other QoS features.


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