Re: hash function over IP address

Path	csiph.com!usenet.pasdenom.info!weretis.net!feeder1.news.weretis.net!feeder.erje.net!news-1.dfn.de!news.dfn.de!fu-berlin.de!uni-berlin.de!individual.net!not-for-mail
From	Rainer Weikusat <rweikusat@mssgmbh.com>
Newsgroups	comp.programming, comp.unix.programmer
Subject	Re: hash function over IP address
Date	Mon, 09 Apr 2012 15:54:28 +0100
Lines	39
Message-ID	<87obr1gdln.fsf@sapphire.mobileactivedefense.com> (permalink)
References	<jliber$ocn$1@speranza.aioe.org> <jlir5m$dd8$1@dont-email.me> <jlk3um$pog$1@speranza.aioe.org> <87bon65l7n.fsf@sapphire.mobileactivedefense.com> <jlkb2b$d5f$1@speranza.aioe.org> <87ehs0g7nn.fsf@sapphire.mobileactivedefense.com> <jluq9v$fig$1@speranza.aioe.org>
Mime-Version	1.0
Content-Type	text/plain; charset=us-ascii
X-Trace	individual.net 35CQiGDkf1PaE0QM23dCjgsCkGz+FbcWnFkGeITXWFn3GjCE4=
Cancel-Lock	sha1:AL3GNB3MMov3KyDh4/xelyQfFCw= sha1:Zf3wfQhDPeoWZPDu7Xaj1S0Vr1g=
User-Agent	Gnus/5.11 (Gnus v5.11) Emacs/22.2 (gnu/linux)
Xref	csiph.com comp.programming:1451 comp.unix.programmer:2393

Cross-posted to 2 groups.

Show key headers only | View raw

"Mark" <mark_cruzNOTFORSPAM@hotmail.com> writes:
> "Rainer Weikusat" <rweikusat@mssgmbh.com> wrote in message 
> news:87ehs0g7nn.fsf@sapphire.mobileactivedefense.com...
>>> Number of next hops is variable, thus anyway it would require to delete 
>>> the
>>> node and re-insert it back with a new key generated, right? (that's not 
>>> an
>>> issue though). How would you suggest to concatenate 32-bit long unsigned
>>> integers, in what form -- convert to strings, concatenate and use such
>>> string as a key?
>>
>> I would consolidate each pair into a 64-bit integer, using 0 in place
>> of a possibly-missing 'second 32-bit number' and then do 'string
>> comparions' on 64-bit integer strings of some length. Whether I would
>> rather store an explicit length together with such a string or use a
>> (64-bit) null terminator would depend on the actual circumstances.
>
> Thanks, this looks reasonable, however I don't understand what do you mean 
> by "each pair"? For instance, given three next hops:
>
> 10.10.10.1
> 20.20.20.1
> 30.30.30.1
>
> this would yield in two 64-bit values:
>
> 10.10.10.1_20.20.20.1
> 30.30.30.1_0.0.0.0

Using another notataion: The three IPv4 addresses

0x0a0a0a01
0x14141401
0x1e1e1e01

would yield the two 64-bit values

0x0a0a0a0114141401
0x1e1e1e0100000000

Back to comp.programming | Previous | Next — Previous in thread | Next in thread | Find similar

Thread

hash function over IP address "Mark" <mark_cruzNOTFORSPAM@hotmail.com> - 2012-04-04 16:37 -0400
  Re: hash function over IP address Barry Margolin <barmar@alum.mit.edu> - 2012-04-04 16:49 -0400
    Re: hash function over IP address China Blue Water Navy <chine.bleu@yahoo.com> - 2012-04-04 14:02 -0700
    Re: hash function over IP address "Mark" <mark_cruzNOTFORSPAM@hotmail.com> - 2012-04-04 17:21 -0400
      Re: hash function over IP address Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2012-04-04 14:47 -0700
  Re: hash function over IP address Ben Pfaff <blp@cs.stanford.edu> - 2012-04-04 14:40 -0700
    Re: hash function over IP address Rainer Weikusat <rweikusat@mssgmbh.com> - 2012-04-04 22:52 +0100
      Re: hash function over IP address blp@cs.stanford.edu (Ben Pfaff) - 2012-04-04 15:35 -0700
        Re: hash function over IP address Rainer Weikusat <rweikusat@mssgmbh.com> - 2012-04-05 12:08 +0100
          Re: hash function over IP address blp@cs.stanford.edu (Ben Pfaff) - 2012-04-05 07:42 -0700
            Re: hash function over IP address Rainer Weikusat <rweikusat@mssgmbh.com> - 2012-04-05 16:29 +0100
          Re: hash function over IP address Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2012-04-05 10:05 -0700
            Re: hash function over IP address Rainer Weikusat <rweikusat@mssgmbh.com> - 2012-04-05 18:12 +0100
              Re: hash function over IP address Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2012-04-05 10:23 -0700
                Re: hash function over IP address Rainer Weikusat <rweikusat@mssgmbh.com> - 2012-04-05 18:34 +0100
                Re: hash function over IP address Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2012-04-05 11:11 -0700
                Re: hash function over IP address Rainer Weikusat <rweikusat@mssgmbh.com> - 2012-04-05 19:34 +0100
                Re: hash function over IP address Rainer Weikusat <rweikusat@mssgmbh.com> - 2012-04-05 19:38 +0100
                Re: hash function over IP address Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2012-04-05 12:18 -0700
            Re: hash function over IP address scott@slp53.sl.home (Scott Lurndal) - 2012-04-05 18:45 +0000
              Re: hash function over IP address "Mark" <mark_cruzNOTFORSPAM@hotmail.com> - 2012-04-05 15:02 -0400
  Re: hash function over IP address Rick Jones <rick.jones2@hp.com> - 2012-04-04 23:18 +0000
  Re: hash function over IP address William Ahern <william@wilbur.25thandClement.com> - 2012-04-04 16:57 -0700
  Re: hash function over IP address Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-04-04 21:05 -0400
    Re: hash function over IP address Barry Margolin <barmar@alum.mit.edu> - 2012-04-04 22:52 -0400
      Re: hash function over IP address Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-04-05 08:46 -0400
    Re: hash function over IP address "Mark" <mark_cruzNOTFORSPAM@hotmail.com> - 2012-04-05 08:42 -0400
      Re: hash function over IP address Rainer Weikusat <rweikusat@mssgmbh.com> - 2012-04-05 15:04 +0100
        Re: hash function over IP address "Mark" <mark_cruzNOTFORSPAM@hotmail.com> - 2012-04-05 10:43 -0400
          Re: hash function over IP address Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-04-05 22:24 -0400
          Re: hash function over IP address Rainer Weikusat <rweikusat@mssgmbh.com> - 2012-04-06 17:13 +0100
            Re: hash function over IP address Rainer Weikusat <rweikusat@mssgmbh.com> - 2012-04-06 17:21 +0100
            Re: hash function over IP address "Mark" <mark_cruzNOTFORSPAM@hotmail.com> - 2012-04-09 10:04 -0400
              Re: hash function over IP address Rainer Weikusat <rweikusat@mssgmbh.com> - 2012-04-09 15:54 +0100
  Re: hash function over IP address BGB <cr88192@hotmail.com> - 2012-04-04 20:21 -0700
  Re: hash function over IP address Udit Gangwani <uditg22@gmail.com> - 2012-04-05 00:26 -0700
  Re: hash function over IP address Rainer Weikusat <rweikusat@mssgmbh.com> - 2012-04-05 12:15 +0100
    Re: hash function over IP address Barry Margolin <barmar@alum.mit.edu> - 2012-04-05 07:52 -0400

csiph-web