Loop in AS macro

Shane Kerr (shane at ripe.net) on January 10:
> Gilles, Wilfried, and all,
> 
> This is not a bug, or even an inconsistency.  Consider the following
> as-macro objects:
> 
>   as-macro: AS-X
>   members:  AS-Y, AS123
> 
>   as-macro: AS-Y
>   members:  AS-X, AS456, AS789
> 
> In this case, AS-X and AS-Y both expand to the same aut-num objects:
> AS123, AS456, and AS789.  However, they may have different maintainers,
> contacts, descriptions, and so on.  In RPSL, many more kinds of loops are
> possible as well, in as-set, route-set, and filter-set objects.

RPSL defines semantics when loops exist. However, it does not promote
them, or prohibit additional restrictions by the registry operators
not to have loops.

> 
> External software that deals with the set objects needs to do loop
> detection in order to prevent infinite loops.  For as-set objects (which
> are as-macro objects in RIPE-181), this is fairly easy:  keep a list or
> hash of the AS sets expanded, and don't expand them again.  For route-set
> and filter-set objects it is not quite so easy.  If you need help with
> these, you can send me and e-mail and I can explain the techniques that
> I've used for these objects.
> 
> Shane Kerr <shane at ripe.net>
> Database Software Engineer
> RIPE NCC
> +31 20 535 4427
> 
> p.s.  This is actually a feature, not an bug.  :)
> 
> p.p.s.  It has been argued (by me) that RPSL allows objects that are
> logically impossible, but the RFC authors don't seem to think so!
> 
> On Wed, 10 Jan 2001, Wilfried Woeber, UniVie/ACOnet wrote:
> 
> >   Hi Gilles,
> >   
> >   I guess we wouldn't be able to check against those accidents at the time
> >   of a DB _update_...
> >   
> >   But checking the RR internal _data_ consistency could maybe become part
> >   of the RIS (or similar) project?
> >   
> >   Henk, any comments?
> >   
> >   An interesting aside: I guess similar problems could occur with
> >   RPSL-based RRs?
> >   
> >   -WW
> >  _________________________________:_____________________________________
> >   Wilfried Woeber                 : e-mail: Woeber at CC.UniVie.ac.at
> >   UniVie Computer Center - ACOnet : Tel: +43 1 4277 - 140 33
> >   Universitaetsstrasse 7          : Fax: +43 1 4277 - 9 140
> >   A-1010 Vienna, Austria, Europe  : RIPE-DB: WW144, PGP keyID 0xF0ACB369
> >  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~:~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > 
> > To: staff at ip.tele.dk, peering at tli.de, ip-oper at tli.de, admin-c at tli.de
> > CC: farrache at cc.in2p3.fr, db-wg at ripe.net, routing-wg at ripe.net
> > Subject: Loop in AS macro
> > Date: Wed, 10 Jan 2001 10:28:15 +0100
> > From: Gilles Farrache <farrache at cc.in2p3.fr>
> > 
> > Dear database managers,
> > 
> > I notice a loop in the followings AS-MACRO, in fact  AS-TELEDANMARKINTERNATIONAL
> > is calling AS-TLI which is calling AS-TELEDK which is calling AS-TELEDANMARKINTERNATIONAL.
> > (and all that make that our automatic filter generation tool fails)
> > 
> > Could you correct those macro and will the Ripe database management provide any 
> > control on that kind of loop ?
> > 
> > Gilles 
> > 
> > as-macro:    AS-TELEDANMARKINTERNATIONAL
> > descr:       Tele Danmark customers outside Denmark
> > as-list:     AS1902 AS12461
> > as-list:     AS8881 AS-KOMTEL
> > as-list:     AS13194 AS-BITE
> > as-list:     AS6709
> > as-list:     AS8650 AS-TLI
> > as-list:     AS8542
> > as-list:     AS12294 AS-TSUA AS6807 AS8349 AS12788 AS12837 AS12872 AS13249 AS15386 AS15497 AS15929 AS16007
> > as-list:     AS12546
> > as-list:     AS15389
> > tech-c:      AS5071-RIPE
> > admin-c:     AS5071-RIPE
> > notify:      staff at ip.tele.dk
> > notify:      peering at tli.de
> > mnt-by:      AS3292-MNT
> > changed:     jesper at skriver.dk 20001103
> > changed:     toba at tdk.dk 20001117
> > changed:     tee at tdk.dk 20001123
> > changed:     jesper at skriver.dk 20001228
> > changed:     jesper at skriver.dk 20010109
> > source:      RIPE
> > 
> > as-macro:    AS-TLI
> > descr:       Talkline GmbH, Internet Division
> > descr:       List of ASes according to Talkline Internet (AS8650)
> > descr:       and customers
> > as-list:     AS5605
> > as-list:     AS6783
> > as-list:     AS8650
> > as-list:     AS8881
> > as-list:     AS12461
> > as-list:     AS12546
> > as-list:     AS-TELEDK
> > as-list:     AS-GLOBAL
> > tech-c:      TLIP1-RIPE
> > admin-c:     TLIP1-RIPE
> > notify:      peering at tli.de
> > mnt-by:      TALKLINE-MNT
> > changed:     thomas at tli.de 19990923
> > changed:     thomas at tli.de 19991020
> > changed:     thomas at tli.de 19991025
> > changed:     thomas at tli.de 20001023
> > changed:     thomas at tli.de 20001025
> > source:      RIPE
> > 
> > as-macro:    AS-TELEDK
> > descr:       Tele Danmark and Tele Danmark customers
> > as-list:     AS-TELEDANMARKDANISH
> > as-list:     AS-TELEDANMARKINTERNATIONAL
> > as-list:     AS-BELBONEMEMBERS
> > as-list:     AS-GLOBAL
> > tech-c:      AS5071-RIPE
> > admin-c:     AS5071-RIPE
> > notify:      staff at ip.tele.dk
> > notify:      peering at tli.de
> > mnt-by:      AS3292-MNT
> > changed:     jesper at skriver.dk 19990922
> > changed:     jesper at skriver.dk 19991019
> > changed:     jesper at skriver.dk 19991025
> > changed:     jesper at skriver.dk 19991210
> > changed:     toba at tdk.dk 20000903
> > source:      RIPE
> > --------------------------------------------------------------------------------
> > 
> 
> 


Cengiz

-- 
Cengiz Alaettinoglu           Packet Design Inc.