How Internet Works
Download as PPT, PDF•6 likes•1,438 views
The document discusses how the Internet works at a high level. It covers Internet topology, elements like IP addresses, autonomous systems, routers and switches. It describes routing protocols used within and between autonomous systems. It also discusses Internet security, MPLS, and how routing is performed between Internet service providers.
![How the Internet works Kae Hsu Communication Network Dept. [email_address]](https://image.slidesharecdn.com/howinternetworks-1227848810240731-8/85/How-Internet-Works-1-320.jpg)
![Internet elements IPv6 address attributes http://www.iana.org/assignments/ipv6-address-space Last update on 2006/2/27 IPv6 Prefix Allocation Reference ----------- ------------------------ ------------ 0000::/8 Reserved by IETF [RFC3513] 0100::/8 Reserved by IETF [RFC3513] 0200::/7 Reserved by IETF [RFC4048] 0400::/6 Reserved by IETF [RFC3513] 0800::/5 Reserved by IETF [RFC3513] 1000::/4 Reserved by IETF [RFC3513] 2000::/3 Global Unicast [RFC3513] 4000::/3 Reserved by IETF [RFC3513] 6000::/3 Reserved by IETF [RFC3513] 8000::/3 Reserved by IETF [RFC3513] A000::/3 Reserved by IETF [RFC3513] C000::/3 Reserved by IETF [RFC3513] E000::/4 Reserved by IETF [RFC3513] F000::/5 Reserved by IETF [RFC3513] F800::/6 Reserved by IETF [RFC3513] FC00::/7 Unique Local Unicast [RFC4193] FE00::/9 Reserved by IETF [RFC3513] FE80::/10 Link Local Unicast [RFC3513] FEC0::/10 Reserved by IETF [RFC3879] FF00::/8 Multicast [RFC3513]](https://image.slidesharecdn.com/howinternetworks-1227848810240731-8/85/How-Internet-Works-7-320.jpg)
How Internet Works
- 1. How the Internet works Kae Hsu Communication Network Dept. [email_address]
- 2. Agenda Internet topology Internet elements IP address & Autonomous system number IPv4, IPv6, ASN attributes Router & switch Routing protocols IGP, EGP Internet security Multiprotocol Label Switching (MPLS)
- 3. About the speaker Join seednet on 2000/12 Maintain network management platform from 2001/1 Maintain frame-relay backbone from 2001/4 Maintain domestic backbone from 2001/7 Maintain domestic peering/transit circuit from 2002/8 Maintain oversea peering/transit circuit from 2004/3 Promotion on 2005/1 Certification SCSA, SCNA (Solaris 8) CCIE#12740 (Routing & switching) JNCIP#266
- 4. Internet topology Autonomous System Autonomous System Autonomous System Autonomous System Autonomous System Autonomous System Autonomous System Autonomous System
- 5. Internet elements IP address IPv4: 32bits address space IPv6: 128bits address space Who will allocate IP address? Local Internet Registry (LIR) ISPs National Internet Registry (NIR) TWNIC in Taiwan, JPNIC in Japan Regional Internet Registry (RIR) APNIC in Asia/Pacific, ARIN in North America Internet Assigned Numbers Authority (IANA) Top level of IP & AS number assigned
- 6. Internet elements IPv4 address attributes Class A, B, C, D, E Public/Private/Specialized IPv4 address Public IP address: Routable address on Internet Private IP address (RFC1918): 10/8 172.16/12 192.168/16 Specialized IPv4 address (RFC3330): Assigned by IANA directly
- 7. Internet elements IPv6 address attributes http://www.iana.org/assignments/ipv6-address-space Last update on 2006/2/27 IPv6 Prefix Allocation Reference ----------- ------------------------ ------------ 0000::/8 Reserved by IETF [RFC3513] 0100::/8 Reserved by IETF [RFC3513] 0200::/7 Reserved by IETF [RFC4048] 0400::/6 Reserved by IETF [RFC3513] 0800::/5 Reserved by IETF [RFC3513] 1000::/4 Reserved by IETF [RFC3513] 2000::/3 Global Unicast [RFC3513] 4000::/3 Reserved by IETF [RFC3513] 6000::/3 Reserved by IETF [RFC3513] 8000::/3 Reserved by IETF [RFC3513] A000::/3 Reserved by IETF [RFC3513] C000::/3 Reserved by IETF [RFC3513] E000::/4 Reserved by IETF [RFC3513] F000::/5 Reserved by IETF [RFC3513] F800::/6 Reserved by IETF [RFC3513] FC00::/7 Unique Local Unicast [RFC4193] FE00::/9 Reserved by IETF [RFC3513] FE80::/10 Link Local Unicast [RFC3513] FEC0::/10 Reserved by IETF [RFC3879] FF00::/8 Multicast [RFC3513]
- 8. Internet elements Autonomous system On the Internet, an autonomous system is a collection of IP networks under the control of a single entity that presents a common routing policy to the Internet . See RFC1930 for detail Autonomous system number (ASN) A public AS has a globally unique number, an Autonomous System number (ASN), associated with it; this number is used in both the exchange of exterior routing information (between neighboring Autonomous Systems), and as an identifier of the AS itself.
- 9. Internet elements ASN address space 2-byte ASN 4-byte ASN (In IETF draft) ASN attribute Public ASN: 1~64511 0000000000000001~1111101111111111 Private ASN: 64512~65535 1111110000000000~1111111111111111 Private ASN is not routable on Internet
- 10. Internet elements Build ISP POPs (Point of presences) Autonomous System ISP POP ISP POP ISP POP ISP POP ISP POP ISP POP
- 11. Internet elements Network topology in ISP POP Three layers architecture Core layer Distribution layer Access layer ISP POP Distribution layer Core layer Access layer
- 12. Internet elements Core layer Use high end router in this layer Cisco System (CSCO) XR 12000 & 12000 series router CRS-1 Carrier Routing System Juniper Networks (JNPR) M series router M7i, M10i, M40e, M120, M320 T series router T320, T640, TX Matrix
- 13. Internet elements Core router: CSCO XR 12000 series router
- 14. Internet elements Core router: CSCO CRS-1 Carrier Routing System
- 15. Internet elements Core router: JNPR M-series router
- 16. Internet elements Core router – JNPR T-series router
- 17. Internet elements Distribution layer Keep local traffic in local Higher port density than core router Much cheaper than core router (per port) Use router or L3 switch Router CSCO 7600 series router JNPR MX960 L3 switch CSCO 6500 series switch Foundry Extreme
- 18. Internet elements Distribution layer router: CSCO 7600
- 19. Internet elements Distribution layer router: JNPR MX960
- 20. Internet elements Distribution layer router: CSCO 6500
- 21. Internet elements Access layer Face to customers Aggregate many low-speed circuit to one or two high-speed circuit Face to customer: T1, E1, ADSL Connect to distribution layer: FE, GE Use access router or Broadband Remote Access Server (BRAS) Router CSCO 3700, 7200, 7300 series router JNPR M-series router BRAS Redback SmartEdge JNPR E-series BRAS routing platform (ERX)
- 22. Internet elements Access layer: CSCO 7200 series router
- 23. Internet elements Access layer: Redback SmartEdge
- 24. Internet elements Access layer: JNPR E-series routing platform
- 25. Internet elements How to connect each equipments in POP? Ethernet family Ten Gigabit Ethernet (10000Mbps) Gigabit Ethernet (1000Mbps) Fast Ethernet (100Mbps) How to connect each POPs? Kinds of circuits SONET/SDH based circuit ATM or Frame-relay based circuit Ethernet based circuit DWDM based circuit Dark fiber
- 26. Internet elements SONET/SDH based circuit SONET: ANSI/Telcordia standard SDH: ITU-T standard Major different in framing structure Basic SONET framing unit: STS-1, 51.84Mbps STS-1 frame size: 6480bits Basic SDH framing unit: STM-1, 155.52Mbps STM-1 frame size: 19440bits Frame rate of SONET/SDH is 8000 frame/sec Use mux/demux to package low-speed circuit (T1/E1/E3/T3/ATM/Ethernet) into SONET/SDH frame Advantage: low overhead SONET/SDH overhead: 3.33% ATM overhead: 9.43%
- 27. Internet elements ATM and Frame-relay based circuit Basic in ATM circuit: cell fix length: 53bytes, use 5 bytes for header speed: from 155Mbps to 622Mbps Basic in Frame-relay circuit: Frame speed: from 64Kbps to 45Mbps Ethernet based circuit Metro Ethernet DWDM based circuit Use different lambda ( λ ) to carry different traffic Physical layer equipment Dark fiber
- 28. Internet elements Routing protocol used by ISP Interior Gateway Protocol (IGP) A set of routing protocols that are used within an autonomous system Opposites: Exterior Gateway Protocol (EGP) Routing protocol used among ISP POPs 100% control by ISP OSPF or IS-IS Routing protocol used between ISP and customer static route for only one circuit Use RIP for multiple circuit
- 29. Internet elements Distance Vector routing protocol Routing Information Protocol (RIP) RIPv1 (classful), RIPv2 (classless), RIPng (IPv6) Interior Gateway Routing Protocol (IGRP) Cisco system property Add other factors for routing selection
- 30. Internet elements Link State routing protocol Open Shortest Path First (OSPF) Based on Dijkstra Shortest Path First algorithm Draft/standardized by Internet Engineering Task Force (IETF) OSPFv2, OSPFv3 (IPv6) Intermediate system to intermediate system (IS-IS) Based on Dijkstra Shortest Path First algorithm Draft/standardized by International Standards Organization (ISO) Enhanced IGRP Cisco system property Integrated link state and distance vector routing protocol
- 31. Internet elements Routing information exchange Access layer propagate customer routes to distribution layer Distribution layer propagate/aggregate customer routes to core layer Core layer exchange POPs routing information Scalability problem?
- 32. Seednet domestic backbone OC3/STM-1 STM-4 GE STM-16/Fiber Router(s) of POP Shiji Taoyuan Hsinchu Yilan Miaoli Taichung Changhwa Yungling Hualian Taitong Pingtong Kaohsiung Tainan NeiHu Nantou Chiayi Icon remark
- 33. Internet elements How to connect to other ASN? Use lots of circuit to connect to other ASN Localloop IPLC Core router colocation in Internet eXchange (IX), use in-house wire to peering with other ASN Use public peering service of IX NOT all of the ASN in the world would peering with you in free Mostly, free peering happened between two ISPs with similar scale Inbound/Outbound traffic is not the key
- 34. Internet elements It is hard to peer with all ASN in the world Cost Cost Cost Transit service Upstream ISP bring Internet traffic to downstream ISP ISPs didn’t need anyone to transit traffic for them: Tier-1 ISP There are 9 Tier-1 ISP defined by wiki
- 35. Seednet exterior status Icon remark Router(s) of POP US Hinet China T3 100M FE TWIX GSN 155M STM-1 Gigamedia GigabitEthernet Asia/HK/JP STM-4 STM-16 JP(NTT) APTG FLAG Taoyuan MOECC(TANet) NCU(600M) NCTU NCHU(600M) NCKU NSYSU(600M) CCU(600M) Taipei ASCC Hsinchu Taichung Chiayi Tainan Kaohsiung
- 36. Internet elements Routing exchange between ISPs Exterior Gateway Protocol EGP Border Gateway Protocol (BGP) BGP Currently: BGP version 4 Lots of attribute for routing control Distance Vector routing protocol Use AS path to prevent routing loop Use AS path length to select best route Flexible on routing tag, attribute re-write, filtering Flexible and capable in attribute extention.
- 37. Internet elements Routing/traffic control by BGP expensive cheap AS100 AS200+AS100 AS100 AS300+AS100 AS400+AS300+AS100 AS100, 192.168/16 AS300 AS200 AS400 AS500
- 38. Internet elements Routing/traffic control by BGP – AS path length AS prepend expensive cheap AS100+AS100+AS100 AS200+AS100+AS100+AS100 AS100 AS300+AS100 AS400+AS300+AS100 AS100, 192.168/16 AS300 AS200 AS400 AS500
- 39. Internet elements Routing/traffic control by BGP – longest match IP blocks slice expensive cheap 192.168/16 192.168/16 192.168/17, 192.168.128/17 192.168/17, 192.168.128/17 192.168/17, 192.168.128/17 AS100, 192.168/16 AS300 AS200 AS400 AS500
- 40. Internet elements Risk in IP blocks slice Normal situation STM-16 FE 192.168/16 192.168/17, 192.168.128/17 192.168/16 AS100, 192.168/16 AS200, transit AS600, peering Internet
- 41. Internet elements Risks in IP blocks slice OOPS situation STM-16 FE 192.168/16 192.168/17, 192.168.128/17 192.168/16 192.168/17, 192.168.128/17 congestion!!! error AS100, 192.168/16 AS200, transit AS600, peering Internet
- 42. Internet elements Use BGP to scale IGP BGP used in the ASN called Interior BGP (iBGP) BGP used between ASN is called Exterior BGP (eBGP) Tiny characteristic difference between iBGP and eBGP Use iBGP to carry customer routes in ASN Add suitable attribute in customer BGP routes Store routes:next-hop information Use IGP to carry next-hop information for iBGP Router will use “recursive lookup” for routing search Check routes:next-hop from iBGP Check next-hop from IGP Forwarding packets to next-hop
- 43. Internet elements Information resource RFC Internet group IANA, RIR NANOG (North American Network Operators' Group) Internet society IETF Internet forum & newsgroup http://www.groupstudy.com/ puck.nether.net Mailing Lists Internet group newsgroup
- 44. Internet security Security issue on BGP Authenticated BGP neighbor? Use MD5 password to protect BGP session Authenticated BGP routes? Routing Assets Database (RADB) IP address & ASes certification APNIC project
- 45. Internet security Discard BGP routes from BGP routes belong private IP addresses RFC1918 Some BGP routes belong specialized IP addresses RFC3330 BGP routes belong private ASN RFC1930 BGP routes belong “Bogon IP blocks” Bogon IP blocks: IP blocks assigned by IANA but not assigned by RIR Discard packets that source IP address belong BGP routes above is safe
- 46. Internet security Prevent IP spoofing Prevent IP spoofing outside your network Check source IP address of packets from your BGP neighbor For packet with source IP address belong your ASN, just discard it Prevent IP spoofing in your network Check source IP address of packets from your customer For packet with source IP address doesn’t belong your customer, just discard it
- 47. Internet security Internet attack TCP sync flooding Smurf attack Distributed Denied of Service
- 48. Internet security Common ways to block DDoS attack Black hole Sink hole
- 49. MPLS Traditional packet forwarding Routing lookup MPLS packet forwarding Each MPLS router will build a database to map routes to special label Use label to forward packet MPLS application MPLS VPN MPLS Traffic Engineering (MPLS TE) MPLS QoS
- 50. MPLS Virtual Private Network (VPN) Traditional VPN Based on ATM and Frame-relay IPsec VPN MPLS VPN Use label stack to differentiate different VPN Provision for L2 or L3 network MPLS TE Use MPLS to pre-build some MPLS TE tunnels Router forward traffic via MPLS TE tunnel path, instead of IGP path. Provide more flexibility than IGP MPLS QoS