NT UDP problem

NTDEV
1

Hello,

I have a LAN emulation NDIS mac driver for a 155 Mbps ATM card on windows
NT. I am returning the link speed as 155Mbps for OID_GEN_LINK_SPEED. But
ttcp (-u)application, when used to transmit UDP packets of size greater
than MTU shows the transmit rate of 250 Mbps.

I would like to know why the link speed is being exceeded? Is there any
other place in which we give the link spped information? This doesn’t
happen for other drivers; for e.g in case of 100 Mbps ethernet driver, the
application shows transmit rate of 85 Mbps.

Regards,
Vinay.

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2

> ttcp (-u)application, when used to transmit UDP packets of size greater

than MTU shows the transmit rate of 250 Mbps.

I would like to know why the link speed is being exceeded? Is there any

UDP has no throttling or flow control, and allows the app to generate too many frames.
NDIS queues in the entrance to NdisSend will drop some of them then - again allowed by UDP.

Max

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