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From solprovi...@apache.org
Subject Re: [users@httpd] hardware for proxy
Date Thu, 11 Sep 2008 16:52:06 GMT
On 9/11/08, Matus UHLAR - fantomas <uhlar@fantomas.sk> wrote:
> > On 9/10/08, Matus UHLAR - fantomas <uhlar@fantomas.sk> wrote:
>  > > On 09.09.08 21:23, solprovider@apache.org wrote:
>  > >  > 5000 reqs/sec @ 20 KB/req = 100 MB/sec = 1Gbps.  One gigabit network1
>  > >  it's even 800, not 1000 Mbits per second...
>  > >  Matus UHLAR - fantomas, uhlar@fantomas.sk ; http://www.fantomas.sk/
>  > Rough conversion (from the old days) was:
>  > 1 byte of data
>  > = 8 bits on disk
>  > = 10 bits of network traffic
> this was also correct in modem times. I don't think that network
>  (http/tcp/ip) headers cause that big overhead now :) Yes, it depends on size
>  of average requests... However we should count that into average size of
>  request...

Network overhead is difficult to estimate.  IPv4 adds 32-36 bytes per
packet; IPv6 adds 60-64 bytes per packet.  Packet size has a large
effect --  smaller packets require more packets with more protocol
overhead ; larger packets waste more space in the final packet.  Then
add non-data packets e.g. ACKs.  My 25% overhead (2 bits overhead per
8 bits data) has produced reasonable estimates.

>  > = 13 bits of encrypted (SSL) network traffic
> Interesting, I guess that mostly applies to SSL handshake overhead. I don't
>  have the numbers but I guess encrypted text should not be much bigger than
>  non-encrypted.

I once read that encryption added 20-30%.  Modern streaming encryption
seems more efficient, but adds handshake overhead per transmission.
Again, my 30% overhead has produced reasonable working estimates.

>  Does somebody have the data?
> Matus UHLAR - fantomas, uhlar@fantomas.sk ; http://www.fantomas.sk/

Ditto.  I would like better estimates, or at least more details to
support my current calculations.

solprovider

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