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Re: hash function over IP address

Cross-posted to 2 groups.

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"Mark" <mark_cruzNOTFORSPAM@hotmail.com> writes:
> First of all, thanks for comments. What I'm trying to solve is to find a way 
> to search in  AVL tree used in IP routing application. Initially a tree's 
> node looked simple:
>
> struct nhlfe_entry
> {
>   u_int32_t nhlfe_ix;
>   u_char opcode;
>   ...
>   struct nhlfe_key key;  /* nexthop key */
> }
>
> /* defines a search key. */
> struct nhlfe_key
> {
>   struct in_addr nh_addr;
>   u_int32_t oif_ix;
>   u_int32_t out_label;
> }
>
> So the search was based on 'struct nhlfe_key'. Now, what I'm trying to add 
> support for multiple next hops, that is I add a linked list in nhlfe_entry:
> struct nhlfe_entry{  u_int32_t nhlfe_ix;  u_char opcode;  ...  struct list 
> *nhkey_list;}where 'struct list' is struct listnode that embeds 'void *data' 
> pointer to caller'sprivate data, and this is 'struct nhlfe_key'.So I'm 
> trying to find the way to generate key based on multiple elements in the 
> list to store/search nodes in the tree.

The simplest solution would be to concatenate all 'next hops' in
order to form a key. A better idea would be to build a so-called radix
search trie based on keys like this. The best online description of
that I found quickly is:

	http://www.cs.hut.fi/Opinnot/T-106.253/k2002/english/extra/digital_search_tree.html

At least the ancient version of this book

	http://www.informit.com/store/product.aspx?isbn=0201314525

I happen to own contains a good description. In contrast to this, the
Wikipedia article completely useless, except as an excellent example
how language can be used to obscure phenomenons instead of explaining
them.

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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

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