IPv6 Fundamentals Ch t ap 1 er I : ntroducti ti t on I o P IPv6 Copyright Cisco Academy Yannis Xydas

Transcription

1 IPv6 Fundamentals Chapter 1: Introduction ti to IPv6 Copyright Cisco Academy Yannis Xydas

2 The Network Today The Internet of today is much different that it was 30, 15 or 5 years ago. 2

3 Technology Tomorrow Now consider what changes will happen within the next 25 years. The Internet of Everything (IoE)... A necessity for IPv6 The IoE is bringing together people, process, data, and things to make networked connections more relevant and valuable. 3

4 The Internet 4

5 42,048,676 IP addresses, 33,899,735 IP links, 281 million destinations, 92.7% of globally routable network prefixes, 39,809 Autonomous Systems (ASes), 152,438 peering sessions. Data collected from 118 monitors located in 42 countries on 6 continents. 5

6 71,391 IPv6 addresses, 186,567 IPv6 links, 4.9 million destinations, 89.3% of globally routable network prefixes, 5,326 Autonomous Systems (ASes), 21,820 peering sessions. Data collected from 47 Ark monitors located in 25 countries on 6 continents. 6

7 The Internet of Things, The Internet of Everything The Internet is more than just connecting people. At the very least we need IPv6 for the Internet to continue. So, the killer application for the Internet is the Internet itself. 7

8 IPv5 In the late 1970s, a family of experimental protocols was developed known as Internet Stream Protocol (ST) and later ST2. Originally defined in Internet Engineering Note IEN-119 (1979) Later revised in RFC 1190 and RFC ST was an experimental resource reservation protocol intended to provide quality of service (QoS) for real-time multimedia applications such as video and voice. Internet Stream Protocol version 2 (ST-II or ST2) was not designed as a replacement for IPv4. 8

9 History of IPv6 IETF began development of a successor to IPv4 in the early 1990s. In 1994, the IETF formed a working group, IP Next Generation, to establish the standards to be used for IPv6: An address architecture and assignment plan Supporting larger packet sizes Tunneling IPv6 packets over IPv4 Security and autoconfiguration The size of the Internet routing tables increasing rapidly and the explosion of the number of Internet users generated a consensus that it was time to begin designing i and testing ti a new network layer protocol as the successor to IPv4. Various projections, including a study done by the IETF in the early 1990s, predicted that the Internet would run out of IPv4 address space somewhere between 2005 and

10 History of IPv6 The three proposals were as follows: Common Architecture for the Internet (CATNIP): CATNIP proposed integrating IP, Internetwork Packet Exchange (IPX), and Connectionless Network Layer Protocol (CLNP). IPX was part of the Internetwork Packet Exchange/Sequenced Packet Exchange (IPX/SPX) suite of protocols used primarily on networks employing the Novell NetWare operating systems. CLNP is an OSI standard defined in ISO 8473 and is the equivalent of IPv4 for the OSI suite of protocols. CATNIP is defined in RFC Simple Internet Protocol Plus (SIPP): SIPP recommended increasing the IPv4 address size from 32 bits to 64 bits, along with additional improvements to the IPv4 header for more efficient forwarding. SIPP is defined in RFC TCP/UDP over CLNP-Addressed Networks (TUBA): TUBA requested minimizing the risk associated with migration to a new IP address by replacing IP with CLNP and its address size of 20 bytes (160 bits). TCP, UDP, and the traditional TCP/IP applications would run on top of CLNP. TUBA is defined in RFCs 1347, 1526, and

11 Monday, January 31, 2011 IANA allocated two blocks of IPv4 address space to APNIC, the RIR for the Asia Pacific region This triggered a global policy to allocate the remaining IANA pool of 5 /8 s equally between the five RIRs. So, basically

12 12

13 RIR IPv4 Address Run-Down Model 13

14 History of IPv6 IETF chose SIPP, written by Steve Deering, Paul Francis, and Bob Hinden, but with an address size of 128 bits. The IETF working group IP Next Generation was formed in In 1995, IETF published RFC 1883, Internet Protocol, Version 6 (IPv6) Specification, which later became obsolete and was replaced by RFC 2460 in In 2001, the IPng working group was renamed to the IPv6 working group. Regional Internet Registries (RIR) began allocating IPv6 addresses to their customers in

15 Benefits of IPv6 Extended address space: IPv6 provides 128-bit source and destination addresses compared to 32-bit addresses with IPv4.This represents an enormous number of addresses: 2 128, or about 340 trillion trillion trillion addresses, enough for every grain of sand on earth. 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 t is the Internet t itself. 15

16 IPv6 is more than just larger address space. It was a chance to make some improvements on the IP protocol. 16

17 Benefits of IPv6 Router Advertisement (Address, prefix, link MTU) Stateless autoconfiguration: IPv6 provides a configuration mechanism where hosts can self-generate a routable address. IPv4-autoconfigured addresses. 17

18 Benefits of IPv6 1 2 Source IP: Source IP: Destination: Destination: Source IP: Destination: Source IP: Destination: XYZ Private RFC 1918 Address / /8 RouterA ISP Public Address: /29 NAT Pool (Host Addresses) / /29 Internet Eliminates the need for NAT/PAT: Because of the large number of public IPv6 addresses, there is no longer a need for Network Address Translation / Port Address Translation (NAT/PAT).. 18

19 Benefits of IPv6 Eliminates broadcasts: IPv6 does not use Layer 3 broadcast addresses. However, IPv6 does employ solicited node multicast addresses, a more efficient and selective technique for processes such as address resolution.. 19

20 Benefits of IPv6 Tunneling IPv6 packets encapsulated inside id IPv4 packets. NAT64 Translating between IPv4 and IPv6. Native IPv6 All IPv6 (our focus and the goal of every organization). Transition tools: IPv6 has a variety of tools to help with the transition from IPv4 to IPv6, including tunneling and NAT. 20

21 When do I have to go to IPv6? IPv4 IPv6 IPv4 and IPv6 will coexist for the foreseeable future. Dual-stack Device running both IPv4 and IPv6. 21

22 Summary How we use the Internet today is much different than it was when IPv4 was developed, with more users, more devices, and new demands. We have moved from just an Internet of computers to an Internet of things/everything. Although no one knows exactly when, we will eventually run out of IPv4 s 4.3 billion addresses, but the fact is that the Internet is in the final stages of public IPv4 address availability. IPv6, with its 128-bit address scheme, provides more than enough globally unique addresses to support the growth of the Internet. IPv4 and IPv6 will coexist for the foreseeable future. IPv6 includes tools and migration strategies that allow both protocols to coexist. The combination of CIDR, NAT, and private addressing has helped slow the depletion of IPv4 address space. However, NAT complicates many applications, including peer-to-peer networking, and with an emerging global Internet community, these enhancements to IPv4 are no longer sufficient. In addition to a larger address space, IPv6 offers additional enhancements such as stateless autoconfiguration and expanded address space without NAT. Now is the best time for IT departments to begin familiarizing themselves with IPv6 before an ordered mandate. The Internet is the killer-application for IPv6. 22

23 IPv6 Fundamentals Chapter 2: IPv6 Protocol Copyright Cisco Academy Yannis Xydas

24 Objectives This chapter describes the IPv6 header by comparing it with the IPv4 header. Explores both the similarities and the differences between IPv4 and IPv6 headers. In addition to the main IPv6 header, a new type of IPv6 header known as an Extension header is also examined. The end of this chapter contains a summary that includes the differences between the IPv4 and IPv6 headers.. 24

25 IPv4 Header To help you better understand the IPv6 header and its enhancements over IPv4, we will first take a look at the IPv4 header. 25

26 IPv6 Header Basic structure of the IPv6 header or what is sometimes referred to as the main IPv6 header. The main IPv6 header can also include one or more IPv6 extension headers. Et Extension headers are explained li dlt later. 26

27 Version (4 bits): This field contains the version number of the IP (Internet Protocol) header. In IPv6, this field is always the value of 6. Traffic Class (8 bits): This field has similar functions to the Type of Service (ToS) field in the IPv4 header. It is the same size as the IPv4 ToS field; only the name has changed. IPv6 uses the Differentiated Services technique specified in RFC 2474, Definition of the Differentiated Services Field (DS Field) in the IPv4 and IPv6 Headers. 27

28 Flow Label (20 bits): The Flow Label field is used to tag a sequence or flow of IPv6 packets sent from a source to one or more destination nodes. Predecessor to MPLS This flow can be used by a source to label sequences of packets for which it requests special handling by the IPv6 routers, such as real-time time service. The Flow Label field is used to help identify all the packets within the same flow to ensure that all the packets receive the same type of handling by the IPv6 routers. Flow Label usage is described in RFC 6437, IPv6 Flow Label Specification. This field is still somewhat experimental 28

29 Payload Length (16 bits): (1 of 2) Length in octets of the payload following the main IP header or, in other words, the data portion of the packet. Including if the IPv6 packet has one or more extension headers. Similar to the Total Length field in the IPv4 header, except for one important difference. IPv4 Total Length field includes both the IPv4 header and the data IPv6 Payload Length field only specifies the number of bytes of data (not the IPv6 header) The IPv4 header can vary in length because of Padding and Options fields, whereas the IPv6 header is fixed at 40 bytes. 29

30 Payload Length (16 bits): (2 of 2) The Payload Length field is 16 bits, allowing a maximum payload size of 65, bytes. IPv6 has a Jumbogram extension header to support larger packet sizes if needed. RFC 2675, IPv6 Jumbograms, specifies an additional 32-bit field to allow the transmission of IPv6 packets with payloads between 65,536 and 4,294,967,295 bytes. Extension headers along with the Jumbo Payload Options are discussed d later in this chapter. 30

31 Next Header (8 bits): This field has two benefits. When there is only the main IPv6 header and no extension headers, the Next Header field specifies the protocol carried in the data portion of the IPv6 packet. This is similar to the Protocol field in the IPv4 header. The same values used in the IPv4 Protocol field are used in the IPv6 along with additional values. Also specifies when there is an Extension header (coming). 31

32 Figure 2-4 Next Header field Next Header 6 TCP Header TCP Data IPv6 Header IPv6 Data Next Header 17 UDP Header UDP Data IPv6 Header IPv6 Data Next Header 58 ICMPv6 Header ICMPv6 Data IPv6 Header IPv6 Data 32

33 Hop Limit (8 bits): Equivalent to the Time to Live (TTL) field in the IPv4 header. Name more reflective of the way that routers treat this field by decrementing the hop limit by 1. Just as with the IPv4 TTL field, if the router decrements the hop limit from 1 to 0, the packet is discarded. In IPv6, an ICMPv6 Time Exceeded message (Type 3, Code 0) is sent to notify the source of the packet that the packet has been dropped. 33

34 Source Address (128 bits): 128-bit IP address of the originator of the IPv6 packet. The source address must be a unicast address. Destination Address (128 bits): 128-bit IP address of the intended final destination or recipient of the IPv6 packet. Can be a unicast or multicast address. Unlike IPv4, there is no broadcast address; however, there is an all-nodes multicast address. 34

35 Extension Headers The Next Header field identifies what follows the Destination Address field: Protocols: TCP (protocol 6) UDP (protocol 17) ICMPv6 (protocol 58) Extension header Extension headers make the handling of options more efficient. (Optional) Extension Header(s) Data 35

36 Extension Headers Multiple extension headers (called a chain) may be included in an IPv6 packet. The number of extension headers is not fixed, so the total length of the extension header chain is variable. The destination node examines the first extension header (if any). The contents determine whether or not the node should examine the next header. Therefore extension headers Therefore, extension headers must be processed in the order they appear in the packet.

37 Extension Header Chain Order Process Next-header value Extension Header Order (protocol #) 1 Hop-by-hop options header 0 2 Destination options header 60 3 Routing header 43 4 Fragment header Authentication header (AH) and ESP header Upper-layer header: TCP UDP ESP = 50 AH = 51 TCP = 6 UDP = 17

38 Extension Headers Next Header 0 Next Header 51 Next Header TCP Header TCP Data 6 Main IPv6 Header Hop-By-Hop Authentication Extension Header Extension Header IPv6 Data Extension headers are optional and follow the main IPv6 header. IPv6 header includes a Next Header field, which has one of two purposes: 1. To identify the protocol carried in the data portion of the packet 2. To identify the presence of an extension header. 38

39 Next Header 0 Next Header 51 Next Header 6 TCP Header TCP Data Main IPv6 Header Hop-By-Hop Authentication Extension Header Extension Header IPv6 Data 39

40 Next Header 0 Next Header 51 Next Header 6 TCP Header TCP Data Main IPv6 Header Hop-By-Hop Authentication Extension Header Extension Header IPv6 Data Intention ti of extension headers is to provide flexibility to the main IPv6 header for future enhancements without having to redesign the entire protocol. This also allows the main IPv6 header to have a fixed size for more efficient i processing. 40

41 Next Header 0 Next Header 51 Next Header 6 TCP Header TCP Data Main IPv6 Header Hop-By-Hop Authentication Extension Header Extension Header IPv6 Data The main IPv6 header has a Next Hop field with the value of 0, indicating that a Hop-by-Hop extension header immediately follows. The Hop-by-Hop extension header follows the main IPv6 header. Extension headers contain their own Next Header field. Its value of 51 signifies that there is yet another extension header to follow, the Authentication Header (AH). The final extension header is the Authentication Header. Its Next Header field has a value of 6, indicating that a TCP upper-layer header is to follow. This also means that there are no more extension headers in this packet. 41

42 IPv4 and IPv6 Header Comparisons After examining the details of the IPv4 and IPv6 headers, it s easy to miss some of the important differences between the two protocols. There was a lot of information to digest, so let s summarize some of these differences. 42

43 These IPv4 field names are the same as those in IPv6: Version (IPv4 and IPv6): This is an easy one Value is 4 in IPv4 and 6 in IPv6 Source Address and Destination Address (IPv4 and IPv6): Probably the most noticeable differences are the 32-bit IPv4 source and destination addresses, which have been increased to 128 bits in IPv6. 43

44 IPv4 field names changed in IPv6 with functional differences in some cases: Type of Service (IPv4) Traffic Class (IPv6): IPv4 can use either the 3-bit IP Precedence field along with another 3 bits for delay, throughput, and reliability, or the 6-bit Differentiated Services technique. IPv6 was designed to use the 6-bit DS method. Total Length (IPv4) Payload Length (IPv6): IPv4 s Total Length field includes both the IPv4 header and the data. IPv6 Payload Length field only specifies the number of bytes of data (payload), including any extension headers, and does not include the main IPv6 header. 44

45 IPv4 field names changed in IPv6 with functional differences in some cases: Time to Live (IPv4) Hop Limit (IPv6): This has the same function in both IPv4 and IPv6, with the name being more reflective of its actual use in IPv6. Protocol (IPv4) Next Header (IPv6): In IPv4, this indicates the protocol being carried in the IPv4 data or payload. In IPv6, same function exists in the Next Header field but can also indicate the existence of an extension header following the main IPv6 header. 45

46 IPv4 fields removed from IPv6: Internet Header Length (IPv4): Not needed in IPv6 because the main IPv6 header has a fixed length of 40 bytes. Any additional headers are linked as indicated d in the Next Header field. Identification (IPv4), Flags (IPv4), and Fragment Offset (IPv4): These fields are used for fragmentation in IPv4. Fragmentation is handled differently in IPv6 using the Fragment extension header. 46

47 IPv4 fields removed from IPv6: Header Checksum (IPv4): Layer 2 data link layer technologies such as Ethernet perform their own checksum and error control. Upper-layer protocols such as TCP and UDP also have their own checksums and therefore a checksum at Layer 3 becomes redundant and unnecessary. A UDP checksum, which is optional in IPv4, is mandatory in IPv6. 47

48 IPv4 fields removed from IPv6: Options (IPv4): Options in IPv4 are now handled using extension headers in IPv6. Two IPv6 extension headers, Hop-by-Hop Options and Destination Options, contain their own set of TLV (Type-Length-Value) options. Padding (IPv4): Because IPv6 has a fixed length of 40 bytes, it is unnecessary to extend the header to make sure that it falls on a 32-bit boundary 48

49 New field in IPv6: Flow Label (IPv6): This is a new field to IPv6, and the specifications of its use are still being determined by the IETF. RFC 2460 does discuss using the Flow Label field to label sequences of packets for needing special handling by IPv6 routers for real-time service. Predecessor to MPLS 49

50 Other Differences Larger Maximum Transmission Unit (MTU) IPv6 requires that every link have a minimum MTU of 1280 bytes, with a recommended MTU of 1500 bytes, compared to 68 bytes in IPv4.. User Datagram Protocol (UDP) The User Datagram Protocol (UDP) Checksum field in IPv4 is optional. Although the protocol remains the same in IPv6, the Checksum field is mandatory in IPv6. This is because the IPv4 header has its own Checksum field but has been removed in the IPv6 header. The Checksum field is used to verify the integrity of the UDP header and data. Fragmentation IPv6 routers do not fragment packets unless the router is the source of the packet. If an intermediate node such as a router receives an IPv6 packet that needs to be fragmented, it will discard the packet and send an ICMPv6 Packet Too Big error message back to the source 50

51 IPv6 Fundamentals Copyright Cisco Academy Yannis Xydas