In einer eMail vom 02.03.2010 13:19:47 Westeuropäische Normalzeit schreibt hannu.fli...@nsn.com:
Hello Heiner, Here are some data bits from the compact routing view: Shortest path routing is incompressible (lower = upper bound): Omega(n log n). yes. There are a set of compact routing universal algorithms that "compresses" routing table to O(n^1/2) (upper bound) with the cost of increasing the worst case stretch to 3 [1,2] . Yuk. I am in favor of inflating (rather than compressing) the (TARA-) routing tables (with multiple spares) so that next hop lookup can be done by either one or three table offsets. Wrt stretch: This term makes only sense, if your solution has to live with stretch 3 and might be happy by avoiding stretch 17. But we should definitely shoot for stretch 1, i.e. have a lot of shortest paths and ,yes, also a plenty of detours. Universal in this context means that nothing is assumed about the graph topology. If you can assume, such as power law distribution for the Internet there are a scheme offering routing table scaling of O[(log n)^2][3]. (here log is log base 2). All of them reduce the routing table size as you can see. See above. I can afford to inflate them. Now, would these schemes be applied to the core BGP to reduce the table size. I do not think so. That's because the BGP works, and fixing something that works is not practical at least cost wise. But these schemes could be used for to limit the growth in the routing system that routes based on the end point identities. Please see my proposal on that part, if you care. It is not only TARA, but with TARA and with quite a few more routing algorithms, routing technology can soar to a new level of perfection. A whole generation of young students could spin the wheel of progress for some decades just as "we" did, based on the current but awfully bad paradigms, for quite a while. Heiner By the way, I would be very much interested to read the TARA specification that you have been referring several years already. Best regards Hannu [1] Krioukov D., kc claffy, K. Fall, and A. Brady. On compact routing for the Internet. ACM SIGCOMM Computer Communication Review (CCR), 37(3), 2007. [2] I. Abraham, C. Gavoille, A. Goldberg, D. Malkhi. "Routing in Networks with Low Doubling Dimensions", Proceedings of the 26th IEEE International Conference on Distributed Computing Systems, p.75, July 04-07, 2006 [3] S. Carmi, R. Cohen, and D. Dolev. "Searching complex networks efficiently with minimal information". Europhysics Letters, 74(6), 2006. >-----Original Message----- >From: rrg-boun...@irtf.org [mailto:rrg-boun...@irtf.org] On >Behalf Of ext Brian E Carpenter >Sent: Tuesday, March 02, 2010 02:06 >To: heinerhum...@aol.com >Cc: nar...@us.ibm.com; rrg@irtf.org >Subject: Re: [rrg] draft-narten-radir-problem-statement-05.txt > >On 2010-03-02 12:36, heinerhum...@aol.com wrote: >... >> Statement: Neither LISP nor any of all the other submitted >solutions >> do reduce the number of routes >> - not even by the number 1. > >IMHO the issue is not to reduce the number of routes but to >limit their growth. At the moment they seem to be limited >loosely like the square root of the size of the Internet, and >our goal is presumably to limit them more strongly than that >-- log(N) would be lovely. > >There is a lot of speculation in this, but since the pressure >towards route de-aggregation seems to come mainly from PI >addressing and the demand for multihoming, a solution that >enables PA aggregation seems certain to limit growth, compared >to doing nothing. There are a number of solutions in the list >that appear to do this. > > Brian > >_______________________________________________ >rrg mailing list >rrg@irtf.org >http://www.irtf.org/mailman/listinfo/rrg >
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