Re: 50000 connections and gigabit speeds

[[e-mail] (Rob Warnock)]

[e-mail] says:
+---------------
| > > It is highly unlikely that one would want to run 
| > > 50,000 tcp connections at gigabit speeds (you would need a 
| > > lot of buffer space).                                    
|
| Why not? The gigabit speed would just decrease the network latency time, 
| wouldn't it? Then you could get the same transaction rate on the host with
| fewer networks. The buffer space needed would not go up. I am interested in
| a transaction environment only, not doing 50,000 file transfers at the same
| time.
+---------------

Then you are going to be mightily disappointed in gigabit networks. Except
for some few cases of mongo-gram transactions in low-diameter LANs, you will
not find gigabit networks decreasing latency much. Consider: An 800 mile T3
link (through two routers) is about 25 ms [as reported by [e-mail],
now [e-mail]]. That latency will not lessen (and it probably will even
even go up a bit) if you run over an OC-12 ATM link (622 Mb/s). Unless each
separate "transaction" is *huge* [which creates error & flow control problems],
an increase in link speed beyond double-digit megabits/sec will not buy you
much of anything.

Even in a LAN, increases in link speed give disappointingly small decreases
in latency. Just ask anybody about NFS over Ethernet versus over FDDI...

Gigabits are for blasting files, not transactions [unless you have 50,000
outstanding transactions or something]....


-Rob

-----
Rob Warnock, MS-9U/510		[e-mail]
Silicon Graphics, Inc.		[phone]
2011 N. Shoreline Blvd.
Mountain View, CA  94043