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The Network Layer: Introducing IPv4, IPv6, and Routing

The Network Layer: Introducing IPv4, IPv6, and Routing. Rick Graziani Cabrillo College graziani@cabrillo.edu. Data Link Trailer. Data Link Header. IP Header. TCP Header. HTTP Header. Data. Data Link Trailer. Data Link Trailer. Data Link Header. Data Link Header. IP Packet. IP Packet.

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The Network Layer: Introducing IPv4, IPv6, and Routing

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  1. The Network Layer: Introducing IPv4, IPv6, and Routing Rick Graziani Cabrillo College graziani@cabrillo.edu

  2. Data Link Trailer Data Link Header IP Header TCP Header HTTP Header Data Data Link Trailer Data Link Trailer Data Link Header Data Link Header IP Packet IP Packet Data Link Trailer Data Link Trailer Data Link Header Data Link Header IP Packet IP Packet Data Link Trailer Data Link Trailer Data Link Header Data Link Header IP Packet IP Packet Data Link Trailer Data Link Header IP Header TCP Header HTTP Header Data

  3. Network Layer Protocols • Network Layer Delivery Protocols • Internet Protocol version 6 (IPv6) • Internet Protocol version 4 (IPv4)

  4. The Network Layer: Introducing IPv4, IPv6, and Routing Rick Graziani Cabrillo College graziani@cabrillo.edu

  5. Characteristics of IP Rick Graziani Cabrillo College graziani@cabrillo.edu

  6. Characteristics of IP • Connectionless: • No connection is established before sending data packets. • Best effort delivery: • No additional overhead is used to guarantee packet delivery. • Media independent: • Operates independently of the medium carrying the data.

  7. ConnectionlessBest Effort

  8. IP Media Independent: "IP over anything" IP doesn’t care what type of media the packet is carried on.

  9. Characteristics of IP Rick Graziani Cabrillo College graziani@cabrillo.edu

  10. Need to Transition from IPv4 to IPv6 Rick Graziani Cabrillo College graziani@cabrillo.edu

  11. Beginning with IPv4 • IPv4 (Internet Protocol version 4) • Developed in the early 1980s • RFC 760 Jan 1980 obsoleted by RFC 791 Sep 1981

  12. IPv4 10.1.1.1 10.1.0.2 • 32-bit addresses represented in dotted-decimal notation. • Provides 4.29 billion addresses. • Why not more addresses? • It seemed like a lot of addresses at the time!

  13. IPv4 - 1981 IPv4 IPv4 was standardized in 1981, provisioning 4.29 billion (232) IP addresses for a world population of 4.41 billion people. * = 100,000,000 = 100,000,000 *www.census.gov IPv4 Addresses World Population 1980 • 4.29 billion addresses, about a 1:1 ratio with the world’s population. • What was the Internet like in 1981? • No WWW, no mobile devices, and most people never heard of the Internet • Mostly mainframe and minicomputers • The IBM PC was introduced trying to overtake the Apple II

  14. The Internet Begins to Take Off • 1990s introduced the World Wide Web. • Everyone was getting on the Internet. • Internet routing tables growing rapidly – 20,000 routes in 1994. • IETF realized that it would soon run out of IPv4 address space.

  15. IPv4: Running Out of Addresses Private Address Space 10.0.0.0/8 172.16.0.0/12 192.168.0.0/16 • Short term solutions included: • NAT (Network Address Translation) • Private address space • CIDR (Classless Inter-Domain Routing) • Long-term solution: IPv6 IPv4

  16. The Need for IPv6 • We are running out of IPv4 address space. • Monday, January 31, 2011 IANA allocated the last /8 IPv4 address blocks to the RIRs. • RIR’s have very few, if any IPv4 address left. • Many ISPs are severely limited and some have already run out. Source: www.potaroo.net/tools/ipv4 Note: APNIC and RIPE are not completely out of addresses but they are very restrictive on allocation of addresses.

  17. Running Out of IPv4 • The regions with the largest populations have the lowest percentages of people connected to the Internet Graphic from Internet World Stats, www.internetworldstats.com/stats.htm

  18. Introducing IPv6 • Not a “new” protocol. • Developed mid to late 1990s. • Much learned from IPv4. • 128-bit address space, written in hexadecimal. • This gives us 340 undecillionaddresses! 128 bits 2001:db8:cafe:1::a736 128 bits 2001:db8:cafe:1::1 340 undecillion = 340,282,366,920,938,463,463,374,607,431,768,211,456

  19. Increased Address Space There are 4.29 billion IPv4 addresses There are 340 undecillion IPv6 addresses

  20. Move from IPv4 to IPv6 • As mentioned previously the benefits of IPv6 include: • Larger address space • Stateless autoconfiguration • End-to-end reachability without private addresses and NAT • Better mobility support • Peer-to-peer networking easier to create and maintain, and services such as VoIP and Quality of Service (QoS) become more robust. • The “killer application” for the Internet is the Internet itself. Graphic from IPv6 Forum, www.ipv6ready.org

  21. Need to Transition from IPv4 to IPv6 Rick Graziani Cabrillo College graziani@cabrillo.edu

  22. Comparing IPv4 and IPv6 Rick Graziani Cabrillo College graziani@cabrillo.edu

  23. Similar fields Understanding IPv4 and IPv6 together IPv4 • Several differences between IPv4 and IPv6 headers. • Simpler IPv6 header. • Fixed 40 byte IPv6 header. • Lets look at the differences… 64-bit memory word IPv6

  24. Version IPv4 • IPv4Version contains 4. • IPv6Version contains 6. • Version 5? • Internet Stream Protocol (ST2) IPv6

  25. IPv4 Internet Header Length IPv4 1 • IPv4 Internet Header Length (IHL) • Length of IPv4 header in 32-bit words including any Options or Padding. • IPv6 • IHL for IPv6 is not needed. • IPv6 header is fixed at 40 bytes. 2 3 4 5 ? IPv6 8 bytes 8 bytes 8 bytes 40 bytes = 8 bytes 8 bytes

  26. IPv4 ToS and IPv6 Traffic Class IPv4 • IPv4 Type of Service • IPv6 Traffic Class • Not mandated by any IPv6 RFCs. • Same functionality as IPv4. • Uses same Differentiated Services technique (RFC 2474) as IPv4. IPv6

  27. IPv6 Flow Label • New field in IPv6 – not part of IPv4. • Flow label is used to identify the packets in a common stream or flow. • Traffic from source to destination share a common flow label. IPv4 11001011000101100 10110010111000111 IPv6

  28. IPv4 Total Length and IPv6 Payload Length IPv4 Header Data (Payload) • IPv4 Total Length – Number of bytes of the IPv4 header (options) + data. • Length of data = total length - IHL • IPv6 Payload Length – Number of bytes of the payload. • Does not include the main IPv6 header. • Includes extension headers + data IPv4 IPv6 Payload IPv6 Header IPv6 Extension Header (Optional) Data Figure 3-6 –IPv4 Total Field and Figure 3-7 – IPv6 Payload Length Field

  29. IPv4 Fragmentation IPv4 • IPv4 fields used for fragmentation and reassembly. • Intermediate devices such as IPv6 routers do not perform fragmentation. • Any fragmentation needed will be handled by the source using an extension header. IPv6

  30. MTU of outgoing link smaller than packet size – fragment IPv4 packet. It is my job to reassemble the packet fragments. IPv4 Fragmentation Link with smaller MTU PCB PCA R1 R2 R3 Destination Source 1 2 3 IPv4 Packet IPv4 Packet IPv4 Packet IPv4 Packet IPv4 Packet IPv4 Packet IPv4 Packet IPv4 Packet

  31. IPv6 No Fragmentation IPv4 IPv6

  32. IPv6 No Fragmentation Packet received. No reassembly required. MTU of outgoing link smaller than packet size. Drop packet. Send ICMPv6 Packet Too Big message, use MTU 1350. I will use MTU of the interface. MTU = 1500 MTU = 1500 MTU = 1500 MTU = 1350 PCB PCA R1 R2 R3 Link with smaller MTU Destination Source 1 IPv6 Packet – MTU 1500 2 ICMPv6 Packet Too Big Use MTU 1350 3 IPv6 Packet MTU 1350

  33. IPv4 Protocol and IPv6 Next Header IPv4 • IPv4Protocol • IPv6Next Header • For both protocols, the field indicates the type of header following the IP header. • Common values: • 6 = TCP • 17 = UDP • 58 = ICMPv6 • 88 = EIGRP • 89 = OSPF IPv6 IPv6 Header Next Header Data (Protocol: TCP, UDP, ICMPv6, etc.)

  34. IPv4 TTL and IPv6 Hop Limit I decrement these fields by 1 and discard the packet if the resulting value is 0. • IPv4TTL (Time to Live) • IPv6Hop Limit • Renamed to more accurately reflect process. • Set by source, every router in path decrements hop limit by 1. IPv4 IPv6 • When 0, drop packet. • No TTL in Ethernet… why do you think they didn’t include one?

  35. IPv4 Header Checksum IPv4 • IPv4Header Checksum • Not used in IPv6. • Upper-layer protocols generally have a checksum (UDP and TCP). • So, in IPv4 the UDP checksum is optional. • Because it’s not in IPv6, the UDP checksum is now mandatory. IPv6

  36. IPv4: TCP and UDP Checksums • UDP checksum, which is optional in IPv4, but is mandatory in IPv6. • The designers of IPv6 did not include a Checksum field because Layer 2 data link technologies such as Ethernet perform their own checksum and error control.

  37. Checksum • IPv4 Header checksum(2 bytes): Simple 16-bit long checksum covers only header. • Upper layer protocols cover data • IP is highest hop-by-hop protocol; need to minimize processing How Checksum is calculated: https://www.youtube.com/watch?v=dXartoyj2ow

  38. IPv6 Source and Destination Addresses IPv4 • IPv6 Source and Destination addresses have the same basic functionality as IPv4. • IPv4 – 32-bit addresses. • IPv6 – 128-bit addresses. • Some significant changes in IPv6. IPv6

  39. IPv4 Options and Padding • IPv4Options and Padding • Not used in IPv6. • Variable length, optional. • IPv4 Options are handled using extension headers in IPv6. IPv4 • Padding makes sure IPv4 options fall on a 32-bit boundary. • IPv6 header is fixed at 40 bytes. • Uses an Extension Header. IPv6 Fixed 40 bytes =

  40. Comparing IPv4 and IPv6 Rick Graziani Cabrillo College graziani@cabrillo.edu

  41. Host Forwarding Rick Graziani Cabrillo College graziani@cabrillo.edu

  42. Default Gateway IP address 192.168.2.30 Subnet mask: 255.255.255.0 Default gateway: 192.168.2.1

  43. Default Gateway – ipconfig C:\Users\Admin>ipconfig Windows IP Configuration Ethernet adapter Local Area Connection: Connection-specific DNS Suffix . : Link-local IPv6 Address . . . . . : fe80::b572:c6c:f983:cadc%11 IPv4 Address. . . . . . . . . . . : 192.168.2.30 Subnet Mask . . . . . . . . . . . : 255.255.255.0 Default Gateway . . . . . . . . . : 192.168.2.1 C:\Users\Admin>

  44. netstat IPv4 Information C:\Users\PC1> netstat -r <Output omitted> IPv4 Route Table =========================================================================== Active Routes: Network Destination Netmask Gateway Interface Metric 0.0.0.0 0.0.0.0 192.168.2.1 192.168.2.30 25 127.0.0.0 255.0.0.0 On-link 127.0.0.1 306 127.0.0.1 255.255.255.255 On-link 127.0.0.1 306 127.255.255.255 255.255.255.255 On-link 127.0.0.1 306 192.168.2.30 255.255.255.0 On-link 192.168.2.30 281 192.168.2.30 255.255.255.255 On-link 192.168.2.30 281 192.168.10.255 255.255.255.255 On-link 192.168.2.30 281 224.0.0.0 240.0.0.0 On-link 127.0.0.1 306 224.0.0.0 240.0.0.0 On-link 192.168.2.30 281 255.255.255.255 255.255.255.255 On-link 127.0.0.1 306 255.255.255.255 255.255.255.255 On-link 192.168.2.30 281 =========================================================================== <Output omitted>

  45. Host Forwarding Rick Graziani Cabrillo College graziani@cabrillo.edu

  46. Default Gateways: Host, Switch, Router Rick Graziani Cabrillo College graziani@cabrillo.edu

  47. Host IP address 192.168.10.10 Subnet mask: 255.255.255.0 Default gateway: 192.168.10.1

  48. Switch

  49. Router

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