Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.os.linux.networking > #3442

Re: number of simultaneous tcp/ip connections on 32 bit linux

Show all headers | View raw

Hi Gargi,

g918273l@gmail.com wrote:

> I have a specific question on implementing a load balancer or a TCP/IP
> server program that does TCP/IP.
> 
> Since port number is 16 bits, there are a max of only 65536 ports on a
> single Linux box at any given time.  And TCP/IP needs a port number to
> talk to the outside world.  
> 1) when a client establishes a connection, an ephemeral port number
>    is chosen.  
> 2) when a server listening on a socket accepts a connection, a port 
>    number is assigned.
> 
> So in my understanding at any given time only maximum 65536 TCP/IP
> connections can exist on a given machine.

No. As pointed out elsewhere, only 65536 different services may be
differentiated. A TCP connection is identified by source-IP, source-port
(choosen "randomly" by client, different for multiple connections to
same server port), server-IP, desintation-port.

> So how is it that some or most load balancers claim 200,000 or more
> concurrent connections?
> 
> Can someone please explain that?

A service, e.g. running on port 80, is able to receive many, many
connections on the same port.

> Also regarding load balancers, once a load balancer has forwarded a
> request to one of the servers behind it, can the load balancer somehow
> pass some information to it, that will help the server to respond back
> to the originating client directly to avoid the latency of sending
> back the response via the load balancer?

I'm not aware of a way to achieve this on network level, because even if
you use DNAT, the packets still need to go back via load balancer since
it needs to re-write the sender address of the server's response.

There might be application level solutions (like redirecting from
www.yourdomein.com to www1...www4.yourdomain.com). On network level you
somehow need to keep the client's "illusion" that it's talking to one
server.

I'm no load balancing expert though and happy to learn something new.
:-)

Jamma.

-- 
"What we nourish flourishes." - "Was wir nähren erblüht."

www.tisc.de

Back to comp.os.linux.networking | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

number of simultaneous tcp/ip connections on 32 bit linux g918273l@gmail.com - 2015-07-27 14:44 -0700
  Re: number of simultaneous tcp/ip connections on 32 bit linux Richard Kettlewell <rjk@greenend.org.uk> - 2015-07-27 23:11 +0100
    Re: number of simultaneous tcp/ip connections on 32 bit linux Bob Martin <bob.martin@excite.com> - 2015-07-28 08:04 +0100
      Re: number of simultaneous tcp/ip connections on 32 bit linux floyd@apaflo.com (Floyd L. Davidson) - 2015-07-27 23:32 -0800
        Re: number of simultaneous tcp/ip connections on 32 bit linux Richard Kettlewell <rjk@greenend.org.uk> - 2015-07-28 09:19 +0100
  Re: number of simultaneous tcp/ip connections on 32 bit linux Jorgen Grahn <grahn+nntp@snipabacken.se> - 2015-07-28 09:15 +0000
    Re: number of simultaneous tcp/ip connections on 32 bit linux Denis Corbin <news@dm3c.org> - 2015-07-28 18:29 +0200
      Re: number of simultaneous tcp/ip connections on 32 bit linux Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2015-07-28 12:51 -0400
        Re: number of simultaneous tcp/ip connections on 32 bit linux Denis Corbin <news@dm3c.org> - 2015-07-28 23:27 +0200
          Re: number of simultaneous tcp/ip connections on 32 bit linux Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2015-07-28 18:27 -0400
            Re: number of simultaneous tcp/ip connections on 32 bit linux Denis Corbin <news@dm3c.org> - 2015-07-29 09:18 +0200
  Re: number of simultaneous tcp/ip connections on 32 bit linux Jamma Tino Schwarze <jamma-usenet@tisc.de> - 2015-08-06 10:12 +0000
    Re: number of simultaneous tcp/ip connections on 32 bit linux JT <JT-reply-only@newsgroup.nl> - 2015-08-06 13:31 +0200
      Re: number of simultaneous tcp/ip connections on 32 bit linux Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2015-08-06 17:40 +0000
      Re: number of simultaneous tcp/ip connections on 32 bit linux Rick Jones <rick.jones2@hp.com> - 2015-08-06 17:04 +0000
      Re: number of simultaneous tcp/ip connections on 32 bit linux Jamma Tino Schwarze <jamma-usenet@tisc.de> - 2015-08-26 13:31 +0000
        Re: number of simultaneous tcp/ip connections on 32 bit linux Richard Kettlewell <rjk@greenend.org.uk> - 2015-08-26 18:33 +0100
          Re: number of simultaneous tcp/ip connections on 32 bit linux Jamma Tino Schwarze <jamma-usenet@tisc.de> - 2015-08-27 14:06 +0000
  Re: number of simultaneous tcp/ip connections on 32 bit linux Dumpsdrive Drive <fromdrive@gmail.com> - 2015-12-19 06:37 -0800

csiph-web