OT: Anyone know how to create network latency?!
gtvlusso
Posts: 5,112
Something that we usually try and avoid, but I need to create a latency for a test - need to create some TCP timeouts....
Any ideas - using Linux LDAP and SOAP....
Any ideas - using Linux LDAP and SOAP....
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Can't physically unplug the wires?FCN 9 || FCN 50
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Nope - boxes are in Germany! And that just gives you a disconnect!0
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can you configure the router or switch so that the TCP timeout is so small that it always does before the receipt is passed back to the originator?Whenever I see an adult on a bicycle, I believe in the future of the human race.
H.G. Wells.0 -
Check latency whilst uploading or downloading a number of 100mb files?
Check latency whilst transfering big files to the site in Germany and back?
Check latency whilst throwing an attack on your firewall?
Install a dodgy NIC?1997 Gary Fisher Big Sur
2009 Scott Spark 60
2010 Ghost 5000
2011 Commencal Ramones AL1
2012 Commencal Meta AM10 -
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Adjust MTU size f at least one of the routers on the way. Make it very small.0
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I would recommend re-setting the bipolarity on the transponster, myself.
Failing that - Ctrl, Alt, Delete.Rules are for fools.0 -
Just go for a ride on your bike and the problem will resolve itself0
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Agree with dodgy, if you can ifconfig the local ethernet MTU size that should reflect back to the stack/application as MSS, if you can control the TCP send/receive window size then setting it down will require more acks/line trurn-around0
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Depends how serious a test you need. We ended up renting a 350km spool of fiber to test SAN replication latency over that distance....Roberts Audax - Raleigh Fixie - Thorn Tandem0
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mzm70 wrote:Agree with dodgy, if you can ifconfig the local ethernet MTU size that should reflect back to the stack/application as MSS, if you can control the TCP send/receive window size then setting it down will require more acks/line trurn-around
May screw up my SSH session to a box I have no way of resetting! Was hoping to be able to buffer packets recvd by the NIC....0 -
Reverse polarity, throw the third switch!FCN 5 belt driven fixie for city bits
CAADX 105 beastie for bumpy bits
Litespeed L3 for Strava bits
Smoke me a kipper, I'll be back for breakfast.0 -
Can you put a box in the way?
on linux, run netem which as it suggests...does network emulation..you can mimic latency etc....
OR on FreeBSD....try dummynet...
same thing really.Whenever I see an adult on a bicycle, I believe in the future of the human race.
H.G. Wells.0 -
You can play with "tc" -- the traffic control manager for your network stack. It's probably already available for your distro.
If you need lots (and lots) of control, then I believe you can use iptables to limit it to certain traffic, although the only use I've seen of iptables for latency is to implement QoS to reduce latency on certain kinds of traffic.
Wow, this *is* OT :-)
Edit: Ah, knew I'd seen it before: LagFactory looks to be a useful wrapper around tc, though I've not actually used it.Sometimes parts break. Sometimes you crash. Sometimes it’s your fault.0 -
set network to download 100 torrents0
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setup http://wanem.sourceforge.net/ and use it as your gateway0
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if you have cisco routers each end then an extended ping test with variable sweeping packet sizes, that will lay down a world of hurt on any WAN connection.
If not use a tool like iperf to generate a massive amount of bi directional traffic across the link then run you latency test at the same time, once the network overload is over your session will return to normal.
again with the cisco end to end WAN safe guard yourself by setting the routers to reload 10 mins after your test ends, just in case you kill the devices (unlikely) you can always log back in and cancel the reboot.
As for your SSH sessions you're using screen or byobu aren't you?Rule #5 // Harden The Feck Up.
Rule #9 // If you are out riding in bad weather, it means you are a badass. Period.
Rule #12 // The correct number of bikes to own is n+1.
Rule #42 // A bike race shall never be preceded with a swim and/or followed by a run.0 -
Greg66 wrote:Have you tried turning it off and back on again?
If that doesn't work, try reinstalling Windows and all your applications.
(What? Isn't that the IT department's standard advice?)
ssssh old man, is that nurse I hear? back to bed now you have finger painting in the morning.Rule #5 // Harden The Feck Up.
Rule #9 // If you are out riding in bad weather, it means you are a badass. Period.
Rule #12 // The correct number of bikes to own is n+1.
Rule #42 // A bike race shall never be preceded with a swim and/or followed by a run.0 -
cee wrote:Can you put a box in the way?
on linux, run netem which as it suggests...does network emulation..you can mimic latency etc....
OR on FreeBSD....try dummynet...
+1. netem here and +1 to wot davis said.
Code written to simulate various network failure conditions is the way to go. Other methods are a little... clunky.The above is a post in a forum on the Intertubes, and should be taken with the appropriate amount of seriousness.0