Routing in 2016, IETF 98
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Routing in 2016 remained stable, with IPv4 growing at around 54,000 new routing prefixes and 3,450 new ASNs per year. IPv6 growth was slower, with around 6,000 new routing prefixes and 1,700 new ASNs per year. While IPv4 addresses are exhausted, routing continues to grow through the increased use of more specific prefixes and the recycling of older addresses. BGP routing tables and updates remained mostly stable and predictable in both IPv4 and IPv6.
Routing in 2016, IETF 98
- 1. Routing in 2016 Geoff Huston Chief Scientist, APNIC
- 2. 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…
- 3. 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 Routing the Internet This is a view pulled together from each of the routing peers of Route- Views
- 5. 2015-2016 in detail average growth trend Route Views Peers RIS Peers
- 6. Routing Indicators for IPv4 Routing prefixes – growing by some 54,000 prefixes per year
- 7. Routing Indicators for IPv4 AS Numbers– growing by some 3,450 prefixes per year
- 8. Routing Indicators for IPv4 More Specifics are still taking up one half of the routing table
- 9. Routing Indicators for IPv4 But the average size of a routing advertisement is getting smaller
- 10. Routing Indicators for IPv4 Address Exhaustion is now visible in the extent of advertised address space
- 11. Routing Indicators for IPv4 The “shape” of inter-AS interconnection appears to be relatively steady, as the Average AS Path length has been steady through the year
- 12. AS Adjacencies (Route-Views) 6,202 AS6939 HURRICANE - Hurricane Electric, Inc., US 5,069 AS174 COGENT-174 - Cogent Communications, US 4,767 AS3356 LEVEL3 - Level 3 Communications, Inc., US 2,632 AS3549 LVLT-3549 - Level 3 Communications, Inc., US 2,397 AS7018 ATT-INTERNET4 - AT&T Services, Inc., US 1,959 AS209 CENTURYLINK-US-LEGACY-QWEST - Qwest, US 1,953 AS57463 NETIX , BG 1,691 AS37100 SEACOM-AS, MU 1,620 AS34224 NETERRA-AS, BG 19,700 out of 57,064 ASNs have 1 or 2 AS Adjacencies (72%) 3,062 ASNs have 10 or more adjacencies 22 ASNs have >1,000 adjacencies
- 13. What happened in 2016 in V4? Routing Business as usual – despite IPv4 address exhaustion! • From the look of the growth plots, its business as usual, despite the increasing pressures on IPv4 address availability • The number of entries in the IPv4 default-free zone is now heading to 700,000 by the end of 2017 • The pace of growth of the routing table is still relatively constant at ~54,000 new entries and 3,400 new AS’s per year • IPv4 address exhaustion is not changing this! • Instead, we are advertising shorter prefixes into the routing system
- 14. 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. IPv4 Advertised 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) 2010
- 16. IPv4 Advertised Address “Age” 24 % of all new addresses announced in 2016 were allocated or assigned within the past 12 months 39 % of all new addresses announced in 2016 were >= 20 years ‘old’ (legacy) 2016
- 17. IPv4: Advertised vs Unadvertised Addresses
- 19. IPv4:Assigned vs Recovered Growth in Advertised Addresses Change in the Unadvertised Address Pool RIR Allocations “recovery” “draw down”
- 20. IPv4 in 2016 The equivalent of 1.8 /8s was added to the routing table across 2016 • Approximately 1.3 /8s were assigned by RIRs in 2015 • 0.7 /8’s assigned by Afrinic • 0.2 /8s were assigned by APNIC, RIPE NCC (Last /8 allocations) • 0.1 /8s were assigned by ARIN, LACNIC • And a net of 0.5 /8’s were recovered from the Unadvertised Pool
- 21. The Route-Views view of IPv6 World IPv6 Day IANA IPv4 Exhaustion
- 23. Routing Indicators for IPv6 Routing prefixes – growing by some 6,000 prefixes per year
- 24. Routing Indicators for IPv6 AS Numbers– growing by some 1,700 prefixes per year (which is half the V4 growth)
- 25. Routing Indicators for IPv6 More Specifics now take up more than one third of the routing table
- 26. Routing Indicators for IPv6 The average size of a routing advertisement is getting smaller
- 27. Routing Indicators for IPv6 Advertised Address span is growing at a linear rate
- 28. Routing Indicators for IPv6 The “shape” of inter-AS interconnection in IPv6 appears to be steady, as the Average AS Path length has been held steady
- 29. AS Adjacencies (Route Views) 9,105 out of 13,197 ASNs have 1 or 2 AS Adjacencies (69%) 917 ASNs have 10 or more adjacencies 4 ASNs have >1,000 adjacencies 3,276 AS6939 HURRICANE - Hurricane Electric, Inc., US 1,607 AS174 COGENT-174 - Cogent Communications, US 1,310 AS3356 LEVEL3 - Level 3 Communications, Inc., US 1,112 AS37100 SEACOM-AS, MU
- 30. 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 1/9 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. What to expect
- 32. BGP Size Projections For the Internet this is a time of extreme uncertainty • Registry IPv4 address run out • Uncertainty over the impacts of market-mediated movements of IPv4 on the routing table • Uncertainty over the timing of IPv6 takeup leads to a mixed response to IPv6 so far, and no clear indicator of trigger points for change for those remaining IPv4-only networks
- 33. V4 - Daily Growth Rates
- 34. V4 - Daily Growth Rates
- 35. V4 - Relative Daily Growth Rates
- 36. V4 - Relative Daily Growth Rates 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
- 37. IPv4 BGP Table Size Predictions Jan 2013 441,000 2014 488,000 2015 530,000 2016 586,000 580,000 2017 646,000 628,000 620,000 2018 700,000 675,000 670,000 2019 754,000 722,000 710,000 2020 808,000 768,000 760,000 2021 862,000 815,000 2022 916,000 Jan 2016 PREDICTION Jan 2015 PREDICTION Jan 2017 PREDICTION
- 38. V6 - Daily Growth Rates
- 39. V6 - Relative Growth Rates
- 40. V6 - Relative Growth Rates Growth 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. Many of 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. IPv6 BGP Table Size predictions Jan 2014 16,100 2015 21,200 2016 27,000 2017 35,000 2018 50,000 43,000 2019 65,000 51,000 2020 86,000 59,000 2021 113,000 67,000 2022 150,000 75,000 Exponential Model Linear Model Range of potential outcomes
- 42. 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. 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
- 44. IPv4 Announcements and Withdrawals
- 46. Updates in IPv4 BGP The number of updates per instability event has been relatively constant Which is good, but why is this happening? Likely contributors to this outcome are the damping effect of widespread use of the MRAI interval by eBGP speakers, and the topology factors, as seen in the relatively constant V4 AS Path Length
- 47. V6 Announcements and Withdrawals
- 48. V6 Convergence Performance High noise components in IPv6
- 49. V6 Updated prefixes per day
- 50. V6 Updates per event
- 51. 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
- 53. Compared to IPv4 IPv6 IPv4 http://bgpupdates.potaroo.net/instability/bgpupd.htmlhttp://bgpupdates.potaroo.net/instability/v6-bgpupd.html
- 54. Updates in IPv6 BGP IPv6 routing behaviour is similar to IPv4 behaviour: Most announced prefixes are stable all of the time And as more prefixes are announced, most of these announced prefixes are highly stable. But for a small number of prefixes we observe highly unstable behaviours that dominate IPv6 BGP updates which appear to be more unstable (relatively) than IPv4
- 55. Today’s State of Routing “Mostly Harmless” The levels of growth of the tables, and the levels of growth of updates in BGP do not pose any immediate concerns The trends are predictable and steady, so network operators can plan well in advance for the capacity of routing equipment to meet their future needs But: The advanced levels of instability by a small number of networks are always annoying! How can we prevent these highly unstable prefixes?
- 56. That’s it!