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North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: exponential route prefix growth, was: Re: The Cidr Report
John Todd wrote: > > Take a look at: > > http://www.fox-den.com/routes/ > > This is a plot of routes v. paths on a router that peers with or at > least sees the tables from a few large upstreams. Please ignore the > large gaps in the chart where I <ahem> did some configuration that > was contrary to the correct functioning of my statistics collection. > This is a crude measurement, but it's useful for trending. I'm sure > someone at CAIDA has done better research than my stupid-simple MRTG > graphs, but I haven't seen theirs mentioned yet so I'll throw my $.02 > in first. > > What is interesting in the growth difference between the two growth > patterns. An interesting trend shows; there is a much larger > increase in the number of paths than in the number of routes. I > would assume that this indicates a growth in the interweaving of > networks, or at least the interweaving of transit providing > relationships. I suspect the interweaving of interconnections is > growing at a similar rate, but proof of this is invisible with only a > few BGP perspectives. > I don't see that, at least in RELATIVE growth. In your "Yearly" graph, number of routes at start = 64 K, number at end = 84 K, ratio = 1.31 number of paths at start = 192 K number at end = 252 K, ratio = 1.31 so both have grown by ~ 31 % in the last year. I don't see how this shows that networks are changing - wouldn't the naive model be growth in routes is proportional to growth in paths, which is what these data show ? I am not saying that the networks aren't getting more interweaved - just that I don't see how these graphs support that belief. Regards Marshall Eubanks > > Perhaps the more vital piece of information in this discussion is not > the sudden growth of routes, but the growth of paths. The > de-aggregation of routes (though I have done no research to prove > this) seems to me simply a response to redundancy/load distribution > issues introduced by current route selection algorithms. I think > we're identifying one of the symptoms, but not the root cause of the > growth in routes. * It seems that we should be saying that there is > a growth in paths, not _just_ routes, and path growth with current > implementation methodologies and reasoning implies route growth. * > > We come back to "BGP only works the way most people expect it to in a > multi-home situation when you de-aggregate a route from one of your > upstreams and announce it all the time to all your peers." Yes, > there are many other reasons that one would de-aggregate and > re-announce either back into the primary with the aggregate or > others; however, I think that the (obvious) basic reasoning for the > bulk of path/route announcements is redundancy and load sharing. > > The demand for "always on" backup ("announce all the time even in > directions in which you pad the path") and cost efficiency ("we're > paying for that second line, so we'd better get some use out of it") > lead to increase in paths that need to be visible, and thus routes > that need to be visible. > > Why in the last year has this been so large? You've got me there, > but I'll take a swing at it. Probably something to do with the > collapsing prices of bandwidth, the dispersion of BGP know-how (or > the "how to set up BGP for your enterprise for dummies" books/FAQs, > at least,) and the sudden expectation that all Internet traffic is > mission-critical and mustmustmust always be available. The bubble of > hype is finally moving down the hose and causing operational issues > such as this. > > It's the nature of the beast; as complexity grows... complexity > grows. So how does this get solved? The complex solutions of > multi-provider NAT are possible, but practically impossible in a > business environment where FUD rules the day. This is really a > matter best discussed after at least 6 hours of deep thought, which > is about 5:55 short of what has occurred for this message. :) > > JT T.M. Eubanks Multicast Technologies, Inc. 10301 Democracy Lane, Suite 410 Fairfax, Virginia 22030 Phone : 703-293-9624 Fax : 703-293-9609 e-mail : [email protected] http://www.on-the-i.com http://www.buzzwaves.com
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