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LFN with small receive window capture wanted

asked 2018-06-18 11:39:19 +0000

NJL gravatar image

Is anyone willing to share a capture of communication across a Long Fat Network (LFN) i.e. high bandwidth with high delay, where the receiver is using a receive window too small to fully utilize the bandwidth?

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answered 2018-06-19 08:19:45 +0000

updated 2018-06-19 08:24:40 +0000

Hi,

see a couple of synthetic samples attached (NTttcp utility, Win10 <--> Win10):

100Mbps 100ms RTT 32kRWIN

100Mbps 100ms RTT 64kRWIN

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Thanks!

How did you create that? Did you also synthesize the latency and bandwidth and if so how?

NJL gravatar imageNJL ( 2018-06-19 10:31:11 +0000 )edit

In this particular case I've used the next setup

100 Mbps are actual NIC speeds whereas latency was injected by Network Emulator For Windows installed on receiver side and bound to corresponding NIC. NTttcp utility has been used for traffic generating and receiver window size controlling.

A bit "hand made" design, not industrial-grade WAN emulator, so you have to consider you can't get microsecond-level precision, but it's good for learning principles of how TCP works.

Packet_vlad gravatar imagePacket_vlad ( 2018-06-19 11:25:41 +0000 )edit

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Asked: 2018-06-18 11:39:19 +0000

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Last updated: Jun 19