Routing for an Anycast CDN

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Routing for an Anycast CDN

  1. 1. Tom PasekaRouting for an Anycast CDN Network Engineer tom@cloudflare.com
  2. 2. What is CloudFlare?CloudFlare makes websites faster and safer using our globallydistributed network to deliver essential services to any website: • Performance • Analytics • Content Optimization • Third party services • Securitywww.cloudflare.com 2
  3. 3. How does CloudFlare Work?CloudFlare works at the network level. • Once a website is part of the CloudFlare community, its web traffic is routed through CloudFlare’s global network of 23 (and growing) data centers. • At each edge node, CloudFlare manages DNS, caching, bot filtering, web content optimization and third party app installations.www.cloudflare.com 3
  4. 4. IPv6 GatewayWith the Internets explosive growthand the number of on-net devicesclosing in on IPv4s maximumcapacity, CloudFlare now offers anautomatic IPv6 gateway seamlesslybridging the IPv4 and IPv6 networks.• For most businesses, upgrading to the IPv6 protocol is costly and time consuming.• CloudFlare’s solution requires NO hardware, software, or other infrastructure changes by the site owner or hosting provider.• Enabled via the flip of a switch on the site owner’s CloudFlare dashboard.• Users can choose two options: (FULL) which will enable IPv6 on all subdomains that are CloudFlare Enabled, or (SAFE) which will automatically create specific IPv6-only subdomains (e.g. www.ipv6.yoursite.com).www.cloudflare.com 4
  5. 5. Anycast CDN
  6. 6. Anycast CDNAnycast prefixes • Same IP Prefixes advertised in each site. • 23 Sites around the world. • No unicast used for content delivery • Unicast used to pull traffic from “origin” and managementTraffic Control • How the eyeball ISP routes • ISP A routes to CloudFlare in Hong Kong, traffic will be served for ISP A from Hong Kong.www.cloudflare.com 6
  7. 7. Anycast CDNTraceroute from Singapore:traceroute to 173.245.61.248 (173.245.61.248), 30 hops max, 40 byte packets 1 202-150-221-169.rev.ne.com.sg (202.150.221.169) 0.351 ms 0.406 ms 0.456 ms 2 s4-6-r10.cyberway.com.sg (203.117.6.209) 0.610 ms 0.652 ms 0.692 ms 3 anutsi10.starhub.net.sg (203.118.3.162) 2.579 ms 2.575 ms 2.562 ms 4 six2utsi1.starhub.net.sg (203.118.3.189) 1.452 ms 1.633 ms 1.768 ms 5 SH.gw5.sin1.asianetcom.net (203.192.169.41) 1.561 ms 1.620 ms 1.610 ms 6 te0-0-2-0.wr1.sin0.asianetcom.net (61.14.157.109) 2.135 ms 1.921 ms 1.950 ms 7 gi4-0-0.gw2.sin3.asianetcom.net (61.14.157.134) 1.909 ms 1.907 ms 1.882 ms 8 CDF-0003.gw2.sin3.asianetcom.net (203.192.154.26) 1.417 ms 1.504 ms 1.493 ms 9 cf-173-245-61-248.cloudflare.com (173.245.61.248) 1.470 ms 1.461 ms 1.520 msTraceroute Completed.Traceroute from Hong Kong:From traceroute.hgc.com.hk to 173.245.61.248traceroute to 173.245.61.248 (173.245.61.248), 64 hops max, 44 byte packets 1 bbs-1-250-0-210.on-nets.com (210.0.250.1) 0.423 ms 0.329 ms 0.320 ms 2 10.2.193.17 (10.2.193.17) 0.719 ms 0.661 ms 0.682 ms 3 peer (218.189.96.62) 0.569 ms 0.550 ms 0.545 ms 4 cloudflare-RGE.hkix.net (202.40.160.246) 1.893 ms 2.419 ms 1.910 ms 5 cf-173-245-61-248.cloudflare.com (173.245.61.248) 2.101 ms 1.973 ms 1.780 mswww.cloudflare.com 7
  8. 8. Anycast CDNDNS QueryDNS result returnedwith “Anycast” IPClient makes connectionto closest serverCloudFlare repliesOutage Re-routes tonext closest cluster Hong Kongwww.cloudflare.com 8
  9. 9. Transit
  10. 10. TransitWho? • Choice of Transit Provider is VERY important • We’ve chosen a limited number of providers per region: • Two in US/EU • Two in Asia. • Single Provider makes routing easier, but two for full reach • Transit provider should offer good routing controls • You need to be able to keep routes within a region • Prepend to specific peers • Transit Provider should make use of “Hot Potato” routing to their peers. • ie. Peer and exchange traffic in every mutual location.www.cloudflare.com 10
  11. 11. TransitRouting Controls? • Must be able to keep advertisements within region. • A Customer of your European transit provider is likely to be a peer of your Asian Transit provider • You don’t want to serve traffic from Asia for Europe • Some routing controls listed on: http://www.onesc.net/communities/ • A lot of work should be done in the presales stage to understand the providers network and how they peer. • Looking at AS1299’s (Telia-Sonera) whois entry gives a good idea how they peer.www.cloudflare.com 11
  12. 12. TransitChoices? • Many providers can give you good coverage for common US and EU Locations (San Jose, LA, New York, London, Amsterdam, etc...) • One provider can’t do it all in Asia. • Asian networks are usually somewhat ‘disconnected’ • Few peer with NTT in Asia • NTT, Pacnet, TATA all disconnected from each other. • Transit in the US could be far cheaper for the provider than within Asia. • Supplement this with Peeringwww.cloudflare.com 12
  13. 13. Peering
  14. 14. PeeringUSA Peering • Is it economic to peer? • Transit is < US$1 • Eyeball networks probably *wont* peer with you • Comcast (not at any exchange) • ATT • South America? • Peering in Miami • Most networks open to peeringwww.cloudflare.com 14
  15. 15. PeeringEU Peering • Same argument as US, might be more costly to peer • Many networks more open to peering however • Major providers / incumbents more difficult, probably wont peer: • DTAG • TeliaSonera • Telecom Italia Sparkle • Telefonica • France Telecom • IX’s have good reach to surrounding regions. • AMS-IX, DE-CIX, netnod, LINXwww.cloudflare.com 15
  16. 16. PeeringAsia Peering • Very economical. • Large providers may not peer • HKIX……. (and Hong Kong Equinix) • Local Loop to HKIX can be around US$1,000 for 1G • No IX charges. • HKIX will get you 100% of domestic Hong Kong. • Very Good Vietnam and some Taiwan, Korea, Japan and China routes too • Singapore Equinix • Priced competitively • Great Coverage for South East Asia (Indonesia, Thailand, Malaysia, India) • JPIX and JPNAP much more costly.www.cloudflare.com 16
  17. 17. PeeringAsia/Hong Kong Peering Economics • Transit ~US$10/M (HK) • HKIX US$2/M at 50% utilisation • Worthwhile after just 100mbit utilization. • If transit is more expensive, justification comes faster! • Hong Kong users will be upset if you don’t peer at HKIX • Quoting a customer: “Having a PoP in HKG without announcing prefixes to HKIX is like a dinner without fork.”www.cloudflare.com 17
  18. 18. PeeringAsia/Sydney Peering Economics • Transit ~US$30+/M • Equinix/PIPE ~US$2/M at 50% utilisation • Worthwhile after around 30mbit. • Around half the “Eyeballs” Connect to Equinix or PIPE in Sydney, WAIX in Perth. • No Telstra, Optus. (or AAPT/Verizon)www.cloudflare.com 18
  19. 19. Challenges
  20. 20. ChallengesChallenges • Routing • Inefficient routing, optimizing. • Turning up peering, causing unexpected routing changes • Russian Network preferred our routes via HKIX instead of in Europe. • Keeping optimal routing to Eyeball Networks • Deployments into new markets • China • South America.www.cloudflare.com 20
  21. 21. ChallengesSOME NETWORKS DO STRANGE THINGS! • An Israeli ISP is doing per-packet load sharing over multiple ISPs • A SYN will connect in Amsterdam • Amsterdam anycast node replies with SYN-ACK • Washington DC receives ACK. • TCP IS BROKEN! • Troubleshooting is not easy.www.cloudflare.com 21
  22. 22. ChallengesHow to troubleshoot? • Whole new techniques • Ping is wonderful tool. • Ping from Anycast IP, to determine if remote side is reachable from that node. • Ping from Unicast IP, to determine if remote side is reachable.www.cloudflare.com 22
  23. 23. Challenges Look at the Seq Numbers Lots of packet losswww.cloudflare.com 23
  24. 24. Challenges Unicast sourced ping looks nicer.www.cloudflare.com 24
  25. 25. Challenges Anycast source ping no reply? Remote side replies to different colo.www.cloudflare.com 25
  26. 26. 26Questions?

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