Analyzing the effec/veness of the CIDR Report. Stephen Woodrow MIT CSAIL

Transcription

1 Analyzing the effec/veness of the CIDR Report Stephen Woodrow MIT CSAIL

2 Outline History of the CIDR Report Analy/cal approach Results Observa/ons about the Report Conclusions 2

3 What this talk is and is not This is specifically about the CIDR Report in the context of deaggrega/on Deaggrega/on and its causes have been considered before: RAS Inconvenient Prefix, NANOG 50 CiUadini et al. Evolu/on of Internet Address Space Deaggrega/on: Myths and Reality, IEEE JSAC October 2010 ripe- 399 RIPE WG on Route Aggrega/on 3

4 History of the CIDR Report Ini/ally a tool to promote CIDR aggrega/on following BGP4 deployment in early- mid 1990s Earliest top 10 list on IETF CIDRD list in 1994 Appeared on NANOG list in September 1996, and soon evolved into its current format Ini/ally launched by Tony Bates & Philip Smith, later transi/oning to Geoff Huston in

5 Ini/ally successful? Down and to the right [April- July 1994] cp://cp.ied.org/ied- online- proceedings/94jul/area.and.wg.reports/ops/cidrd/cidrd.bates.slides.ps 5

6 Why did it (presumably) work? Providing informa/on to the clueless Social forces Shame and reputa/on Peer pressure The CIDR Police (NANOG 27) 6

7 Is the CIDR Report s/ll effec/ve? Not anymore, but it worked $N years ago from several people I spoke to Doesn t mauer; Rou/ng table growth isn t a problem anymore, thanks to Moore s law No longer needed to promote classful- to- classless transi/on No empirical study? 7

8 Defining effec/ve Hypothesis: If the CIDR Report works, it should encourage aggrega/on in order to reduce one s ranking. Thus: Does an AS improve its aggrega1on behavior a4er appearing on the CIDR Report? Aggrega/on behavior in terms of: Deaggrega/on factor (netsnow/netsaggr) Aggregable prefixes (netgain) 8

9 Measuring AS behavior Archived CIDR Reports are not sufficient Rela/ve ranking dropping off top 30 is ambiguous: did AS improve, or did others become worse? Re- implemen/ng the CIDR Report Data: Route Views RIBs Preprocess to canonicalize AS_PATH Mark prefix aggregable if any RV peer can aggregate Some differences, but generally consistent 9

10 Measuring change in AS behavior Aggregable Prefixes First appearance (t=0) t+30 days t+60 t+90 t+180 t+365 t+547 t+720 t CIDR Report Rank Date 10

11 Measuring change in AS behavior Locate each AS first appearance on the Report Sample at various periods acer appearance Establish control group of ASes Same number as in treatment group Randomly selected from ASes never appearing Must adver/se at least 10 prefixes Must be visible for full sampling period 11

12 Measures of deaggrega/on Deaggrega/on factor (DF) actual number of prefixes adver/sed by an AS minimum number of prefixes required for AS rou/ng policy netgain the number of prefixes adver/sed by an AS that could be withdrawn without altering rou/ng policy 12

13 Deaggrega/on factor over /me P(X x) , treatment, t Deaggrega/on factor (netsnow / (netsnow netgain)) 1 Jan Dec

14 Deaggrega/on factor over /me P(X x) , treatment, t Deaggrega/on factor (netsnow / (netsnow netgain)) 1 Jan Dec

15 Deaggrega/on factor over /me P(X x) , treatment, t , treatment, t Deaggrega/on factor (netsnow / (netsnow netgain)) 1 Jan Dec

16 Deaggrega/on factor over /me P(X x) , treatment, t , treatment, t Deaggrega/on factor (netsnow / (netsnow netgain)) 1 Jan Dec

17 Deaggrega/on factor over /me P(X x) , control, t Deaggrega/on factor (netsnow / (netsnow netgain)) 1 Jan Dec

18 Deaggrega/on factor over /me P(X x) , control, t , control, t Deaggrega/on factor (netsnow / (netsnow netgain)) 1 Jan Dec

19 At first, the top 30 mostly improve, while the control group deaggregates P(X x) , treatment, t , treatment, t , control, t , control, t P(X x) Deaggrega/on factor (netsnow / (netsnow netgain)) 1 Jan Dec , treatment, t , treatment, t , control, t+0 19

20 Over /me, aggrega/on improvement by top 30 decreases P(X x) , treatment, t , treatment, t , control, t , control, t Deaggregation factor (netsnow (netsnow netgain)) P(X x) Deaggrega/on factor (netsnow / (netsnow netgain)) 1 Jan Dec , treatment, t , treatment, t , control, t+0 20

21 P(X x) Over /me, aggrega/on improvement by top 30 decreases , treatment, t , treatment, t , control, t , control, t Deaggregation factor (netsnow (netsnow netgain)) P(X x) , treatment, t , treatment, t , control, t , control, t Deaggregation factor (netsnow (netsnow netgain)) P(X x) Deaggrega/on factor (netsnow / (netsnow netgain)) 1 Jan Dec , treatment, t , treatment, t , control, t+0 21

22 Deaggregation factor (netsnow (netsnow netgain)) P(X x) Over /me, aggrega/on improvement by top 30 decreases , treatment, t , treatment, t , control, t , control, t Deaggregation factor (netsnow (netsnow netgain)) P(X x) , treatment, t , treatment, t , control, t , control, t Deaggregation factor (netsnow (netsnow netgain)) Deaggrega/on factor (netsnow / (netsnow netgain)) 1 Jan Dec

23 Interpre/ng these data Control groups are consistent over /me Improvement in deaggrega/on factor has decreased over /me If CIDR Report was source of previous behavior change, it is no longer effec?ve Poten/al confounding factors Selec/on Bias: Top 30 ASes may be intrinsically different than other networks Regression to the mean 23

24 Why the change? Theories: RIB/FIB slots are plen/ful less pain/concern Increased need for deaggrega/on (TE, etc.) Change in community response s per week weekly CIDR Report below this line Analyzing the effec/veness Date of the CIDR Report / NANOG 53 24

25 Observa/ons about the Report CIDR Report was ini/ally developed to encourage CIDR- iza/on It has remained essen?ally unchanged since, while the Internet has grown and changed 25

26 With fixed top 30, the Report focuses on outlier behavior as Internet grows P(X! x) Top 30, 2011 Top 30, Aggregable prefixes (netgain) Threshold lines indica/ng the cut- off point for appearing on the CIDR Report in 1998 and 2011 are indicated. Note that the graph is rescaled; approximately 70% of ASes in the rou/ng table do not adver/se any aggregable prefixes. 26

27 The top of the Report contains ASes with extreme netgains: hard to displace Aggregable prefixes (netgain) netgain of rank 1 netgain of rank 2 netgain of rank 3 netgain of rank 4 netgain of rank 5 netgain of rank 10 netgain of rank 15 netgain of rank Date 27

28 Should we do something about the CIDR Report? Unclear whether rou/ng table growth is a pain point right now or in the near future CIDR Report would probably not be the best way to deal with painful growth FIB aggrega/on/compression New interdomain rou/ng architecture (RFC 6115) But, if it s something operators care about, it could probably be improved e.g. focus on more ac/onable behavior: low- hanging fruit or recent offenders 28

29 Conclusions The CIDR Report appeared effec/ve in its early days (though it s difficult to establish causality) There are a number of poten/al contribu/ng factors for its decreased efficacy over /me The CIDR Report has not evolved with the Internet, but it probably could be improved Social forces in the operator community may yet have value in solving problems 29

30 More detail: hup://people.csail.mit.edu/woodrow/sm- thesis.pdf Analyzing the effec/veness of the CIDR Report / NANOG 53 30