BGP in 2015
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The document discusses the evolving landscape of internet routing over the years, highlighting the impact of IPv4 address exhaustion and the steady growth of routing prefixes. It notes the differing growth rates of IPv4 and IPv6, with IPv4 growth remaining constant despite exhaustion, while IPv6 growth is slower but increasing. The document emphasizes ongoing challenges and uncertainties in network management, specifically regarding the stability and behavior of BGP (Border Gateway Protocol) amid changing address allocations.
BGP in 2015
- 2. 2016#apricot2016 Through the Routing Lens There are very few ways to assemble a single view of the entire Internet The lens of routing is one of the ways in which information relating to the entire reachable Internet is bought together Even so, its not a perfect lens…
- 4. 2016#apricot2016 There is no Routing God! There is no single objective “out of the system” view of the Internet’s Routing environment. BGP distributes a routing view that is modified as it is distributed, so every eBGP speaker will see a slightly different set of prefixes, and each view is relative to a given location So the picture I will be painting here is one that is drawn from the perspective of AS131072. This is a stub AS at edge of the Internet, and this is an eBGP view. You may have a similar view from your network.
- 5. 2016#apricot2016 1994: Introduction of CIDR 2001: The Great Internet Boom and Bust 2005: Broadband to the Masses 2009: The GFC hits the Internet 2011: Address Exhaustion 20 Years of Routing the Internet This is a view pulled together from each of the routing peers of Route Views
- 6. 2016#apricot2016 1994: Introduction of CIDR 2001: The Great Internet Boom and Bust 2005: Broadband to the Masses 2009: The GFC hits the Internet 2011: Address Exhaustion 20 Years of Routing the Internet This is a view pulled together from each of the routing peers of Route Views
- 7. 2016#apricot2016 2015, as seen at Route Views
- 8. 2016#apricot2016 2015, as seen at Route Views Initial growth rate
- 9. 2016#apricot2016 2015, as seen at Route Views Initial growth rate annual growth rate
- 10. 2016#apricot2016 Routing Indicators for IPv4 Routing prefixes – growing by some 47,000 prefixes per year AS Numbers– growing by some 3,100 prefixes per year
- 11. 2016#apricot2016 Routing Indicators for IPv4 More Specifics are still taking up one half of the routing table But the average size of a routing advertisement is getting smaller
- 12. 2016#apricot2016 Routing Indicators for IPv4 Address Exhaustion is now visible in the extent of advertised address space The “shape” of inter-AS interconnection appears to be relatively steady, as the Average AS Path length has been steady through the year
- 13. 2016#apricot2016 What happened in 2015 in V4? • From the look of the growth plots, its business as usual, despite the increasing pressure on IPv4 address availability • The number of entries in the default-free zone is now heading to 600,000 • The pace of growth of the routing table is still relatively constant at ~50,000 new entries per year – IPv4 address exhaustion is not changing this!
- 14. 2016#apricot2016 How can the IPv4 network continue to grow when we are running out of IPv4 addresses? We are now recycling old addresses back into the routing system Some of these addresses are transferred in ways that are recorded in the registry system, while others are being “leased” without any clear registration entry that describes the lessee
- 15. 2016#apricot2016 Address “Age” 80% of all new addresses announced in 2010 were allocated or assigned within the past 12 months 2% of all new addresses announced in 2010 were >= 20 years ‘old’ (legacy) Address “age” in 2010
- 16. 2016#apricot2016 IPv4 Address Reuse 20 % of all new addresses announced in 2015 were allocated or assigned within the past 12 months 33 % of all new addresses announced in 2015 were >= 20 years ‘old’ (legacy) Address “age” in 2015
- 17. 2016#apricot2016 IPv4 in 2015 – Growth is Steady • Overall IPv4 Internet growth in terms of BGP is at a rate of some ~47,000 entries p.a. • But we’ve run out of the unallocated address pools everywhere except Afrinic • So what’s driving this post-exhaustion growth? – Transfers? – Last /8 policies in RIPE and APNIC? – Leasing and address recovery?
- 18. 2016#apricot2016 IPv4: Advertised vs Unadvertised Addresses
- 20. 2016#apricot2016 IPv4: Unadvertised Addresses This is expected! This is not!
- 23. 2016#apricot2016 IPv4 in 2015 Approximately 4 /8s were assigned and advertised in 2015 – 2.3 /8s were assigned by ARIN – 1 /8 assigned by AfriNIC Up to 3 /8s were ‘recovered’ from the unallocated address pool and advertised during 2015 – But 2/8s of addresses were withdrawn in the last two months of the year
- 24. 2016#apricot2016 The Route Views view of IPv6 World IPv6 Day IANA IPv4 Exhaustion
- 25. 2016#apricot2016 2015 for IPv6, as seen at Route Views
- 26. 2016#apricot2016 Routing Indicators for IPv6 Routing prefixes – growing by some 6,000 prefixes per year AS Numbers– growing by some 1,600 prefixes per year (which is half the V4 growth)
- 27. 2016#apricot2016 Routing Indicators for IPv6 More Specifics now take up one third of the routing table The average size of a routing advertisement is getting smaller
- 28. 2016#apricot2016 Routing Indicators for IPv6 Advertised Address span is growing at a linear rate The “shape” of inter-AS interconnection appears to be steady, as the Average AS Path length has been held steady through the year
- 29. 2016#apricot2016 IPv6 in 2015 • Overall IPv6 Internet growth in terms of BGP is steady at some 6,000 route entries p.a. This is growth of BGP route objects is 1/7 of the growth rate of the IPv4 network – as compared to the AS growth rate which is 1/2 of the IPv4 AS number growth rate
- 31. 2016#apricot2016 BGP Size Projections For the Internet this is a time of extreme uncertainty • Registry IPv4 address run out • Uncertainty over the impacts of any after-market in IPv4 on the routing table • Uncertainty over IPv6 takeup leads to a mixed response to IPv6 so far, and no clear indicator of trigger points for change
- 32. 2016#apricot2016 V4 - Daily Growth Rates
- 33. 2016#apricot2016 V4 - Daily Growth Rates
- 34. 2016#apricot2016 V4 - Relative Daily Growth Rates
- 35. 2016#apricot2016 Growth in the V4 network appears to be constant at a long term average of 120 additional routes per day, or some 45,000 additional routes per year Given that the V4 address supply has run out this implies further reductions in address size in routes, which in turn implies ever greater reliance on NATs Its hard to see how and why this situation will persist at its current V4 - Relative Daily Growth Rates
- 36. 2016#apricot2016 IPv4 BGP Table Size predictions Jan 2013 441,000 2014 488,000 2015 530,000 540,000 2016 586,000 580,000 590,000 2017 628,000 620,000 640,000 2018 675,000 670,000 690,000 2019 722,000 710,000 740,000 2020 768,000 760,000 2021 815,000 These numbers are dubious due to uncertainties introduced by IPv4 address exhaustion pressures. 2014 PREDICTION 2013 PREDICTION
- 38. 2016#apricot2016 V6 - Daily Growth Rates
- 39. 2016#apricot2016 V6 - Relative Growth Rates
- 40. 2016#apricot2016 V6 - Relative Growth RatesGrowth in the V6 network appears to be increasing, but in relative terms this is slowing down. Early adopters, who have tended to be the V4 transit providers, have already received IPv6 allocation and are routing them. The trailing edge of IPv6 adoption are generally composed of stub edge networks in IPv4. These networks appear not to have made any visible moves in IPv6 as yet. If we see a change in this picture the growth trend will likely be exponential. But its not clear when such a tipping point will occur
- 41. 2016#apricot2016 IPv6 BGP Table Size predictions Jan 2014 16,100 entries 2015 21,200 2016 27,000 2017 38,000 30,000 2018 51,000 35,000 2019 70,000 40,000 2020 94,000 44,000 2021 127,000 49,000 Exponential Model Linear Model Range of potential outcomes
- 42. 2016#apricot2016 BGP Table Growth • Nothing in these figures suggests that there is cause for urgent alarm -- at present • The overall eBGP growth rates for IPv4 are holding at a modest level, and the IPv6 table, although it is growing at a faster relative rate, is still small in size in absolute terms • As long as we are prepared to live within the technical constraints of the current routing paradigm, the Internet’s use of BGP will continue to be viable for some time yet • Nothing is melting in terms of the size of the routing table as yet
- 43. 2016#apricot2016 BGP Updates • What about the level of updates in BGP? • Let’s look at the update load from a single eBGP feed in a DFZ context
- 47. 2016#apricot2016 Updates in IPv4 BGP Nothing in these figures is cause for any great level of concern … – The number of updates per instability event has been relatively constant, which for a distance vector routing protocol is weird, and completely unanticipated. Distance Vector routing protocols should get noisier as the population of protocol speakers increases, and the increase should be multiplicative. – But this is not happening in the Internet – Which is good, but why is this not happening? Likely contributors to this outcome are the damping effect of widespread use of the MRAI interval by eBGP speakers, and the topology factor, as seen in the relatively constant V4 AS Path Length
- 48. 2016#apricot2016 V6 Announcements and Withdrawals
- 50. 2016#apricot2016 V6 Updated prefixes per day
- 51. 2016#apricot2016 V6 Updates per event
- 52. 2016#apricot2016 Updates in IPv6 BGP IPv6 routing behaviour is diverging from IPv4 behaviour The instability is greater Its not the number of unstable prefixes, but the number of updates and elapsed time for the network to re-converge for each instability event It this were to happen in the V4 network at the same relative scale it would be a major stability problem! So what is going on and why has this happened?
- 53. 2016#apricot2016 Updates in IPv6 BGP Route Updates are very unequally distributed across the prefix set – they appear to affect a very small number of prefixes which stand out well above the average
- 54. 2016#apricot2016 Updates in IPv6 The busiest 48 prefixes accounted for 2/3 of all prefix updates