Throughput jaringan yang sebenarnya

mendapatkan speed optimum untuk networking memang tidak mudah tetapi apakah benar bottleneck terdapat pada network. Misalnya jaringan suatu kantor menggunakan jaringan tipe gigabit. artinya


GigE = 1000 Megabits/sec = 125MB/sec

bagaimana mengukur kecepatan real dari bandwidth kita ?

gunakan iperf
install sebagai server iperf -s
test sebagai client iperf -c

hasilnya kayak berikut

------------------------------------------------------------
Client connecting to 192.168.0.130, TCP port 5001
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[  3] local 192.168.0.132 port 37378 connected with 192.168.0.130 port 5001
[  3]  0.0-10.0 sec  1.02 GBytes    880 Mbits/sec

artinya kecepatan throughput adalah 880 Mb/s = 110 MB/s

kondisi diatas adalah kondisi ideal hanya simulasi melalui network.

Didalam aplikasi yang real hal ini jarang ditemui sampai mencapai nilai demikian sebab banyak hal yang mempengaruhi. antara lain

• Speed of Hard Drive [if your hard drive can only read/write at 30MB/sec consistently, the highest theoretical network throughput would be 240Mbps [about a quarter of GigE's theoretical maximum ] 100MB+/sec Hard Drive read speeds are generally only found in server class hard drives and/or drive arrays.
  
  
• Application Performance
  Windows File Sharing [with the exception of Windows 2008 and Windows Vista native environments] was not optimized for high bandwidth operation. Windows XP is simply not capable of performing Gigabit speed file transfers out of the box when using the SMB protocol. The next generation of the SMB protocol [SMB 2.0] which has been implemented in Windows 2008 Server and Windows Vista is capable of utilizing the potential of the bandwidth available in Gigabit networks.
  
  Testing for Gigabit Bottlenecks
  One of the best ways of benchmarking Gigabit network performance is to test the network while eliminating as many client based bottlenecks as possible. Using a tool that does not need to read/write from the Hard Drive is recommended. One such tool IPERF has been shown to work reliably in benchmarking performance. Many members of this forum have seen 900+ Mpbs [90% of Gigabit throughput ] between two hosts on the same network [using consumer grade Gigabit switches and laptops and or PCs with integrated [on motherboard] Gigabit adapters.
  
  
• Bad Cable
  
  
• PCI Bus Speed
  If your gigabit network card is on a normal 33mhz/32-bit PCI slot

taken from episteme.arstechnica.com

Cara menghitung throughput bandwidth

data sebesar 30 MB
HD sata = 1.5 Gb/s = 187.5 MB/s

baca dari hd 187.5 MB/s = 0.16 s

transfer 30 / 110 = 0.3 s

tulis e hd 187.5 MB/s = 0.16 s

waktu yang dibutuhkan memindahan data adalah 0.62 detik untuk 30 MB
kecepatan teoritical untuk transfer antar komputer dengan hd sata menggunakan gigabit ethernet adalah 48 MB/s