RINA - scott whaps at the nanog hornets nest :-)

George Bonser gbonser at seven.com
Sun Nov 7 01:54:40 CST 2010



> 
> Oh, come on. Get real. The world TCP speed record is 10GE right now,
> it'll
> go higher as soon as there are higher interface speeds to be had.

You can buy 100G right now.  I also believe there are some 40G
available, too.

Also, check this:

http://media.caltech.edu/press_releases/13216

That was in 2008.  

 
> I can easily get 100 megabit/s long-distance between two linux boxes
> without tweaking the settings much.

Until you drop a packet.  I can get 100 Megabits/sec with UDP without
tweaking it at all.  Getting 100Meg/sec San Francisco to London is a
challenge over a typical Internet path (i.e. not a dedicated leased
path).

> Or they might tweak some other TCP settings and get 30 meg/s with
> existing
> 1500 MTU. It's WAY easier to tweak existing TCP than trying to get the
> whole network to go to a higher MTU. We do 4470 internally and on
> peering
> links where the other end agrees, but getting it to work all the way
to
> the end customer isn't really easy.

I guess you didn't read the links earlier.  It has nothing to do with
stack tweaks.  The moment you lose a single packet, you are toast.  And
there is a limit to how much you can buffer because at some point it
becomes difficult to locate a packet to resend.  *If* you have a perfect
path, sure, but that is generally not available, particularly to APAC.

> But in a transition some end systems will have 9000 MTU and some parts
> of
> the network will have smaller, so then you get problems.

Which is no different than end systems that have 9000 today.  A lot of
networks run jumbo frames internally now. Maybe a lot more than you
realize.  When you are using NFS and iSCSI and other things like
database queries that return large output, large MTUs save you a lot of
packets. NFS reads in 8K chunks, that can easily fit in a 9000 byte
packets.  It is more common in enterprise and academic networks that you
might be aware.





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