Unanswered Question
Apr 30th, 2009

Suppose we have 10 mb link on fast0/1 and we have configured the port to 256 KB..Will the router send or recive load more than 256 KB i.e up to 10MB.

I have this problem too.
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Joseph W. Doherty Thu, 04/30/2009 - 05:01

Much depends on what you mean by "we have configured the port to 256 KB".

If Etherent interface is configured for 10 Mbps, each frame will be sent at 10 Mbps. There are QoS settings on various devices to drop or delay frames/packets such that the average bandwidth utilization is less than link capacity.

irfan_1505 Thu, 04/30/2009 - 05:10

Confused...i just want say that i am upload file from this interface and the file size is 10 MB..and i open a bandwidth gauge then what it will show me utilization of 10 Mb or 256 Kb..I mean say will it transfer 10 MB Load or will transfer 256 ...256.. can Bandwidth command create any impact on load..??

Laurent Aubert Thu, 04/30/2009 - 05:34


It's not because you have a local 10M interface that you have 10M available between you and your FTP server. There are many links in the middle which may not be able to provide 10M. It depends also of the performance of the hosts to transmit as well.

That's why TCP has congestion avoidance and retransmission mechanism, so it can adapt its transmit rate to the network availability.

Also, the Bw showed by your application usually doesn't take into account the L4/L3 and L2 overhead so it's normal to have a smaller value than the actual Bw you are using from a network point of view.



Joseph W. Doherty Thu, 04/30/2009 - 05:38

The bandwidth command setting on an interface doesn't usually have direct control over transmission rate of the interface. However, it could have indirect control if, for instance, a percentage based shaper or policer was applied.

As to bandwidth guages and file upload, many factors apply. Everything from bits to bytes, Ethernet overhead, protocol effciency, host capacity, MTU, etc.

Laurent Aubert Thu, 04/30/2009 - 05:04


If you mean you are policing this port to 256 Kbps in and out then it depends of your exceed-action configuration. If you drop any exceeding traffic then 256 Kbps is your max Bw available.

Let me know if I misunderstood your question



irfan_1505 Thu, 04/30/2009 - 06:02

it means the BW command is no realation to load, if i am using 10 MB link and i configured the port to 256 KB then i am able to trasmission rate more than 256 KB..means i will not get any packet drops beyond 256 KB..Am i right..?


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