Network Layer Part A (IPv6) Network Layer 4-1 Chapter 4: outline - PowerPoint PPT Presentation

Network Layer – Part A (IPv6) Network Layer 4-1

Chapter 4: outline 4.1 Overview of Network 4.4 Generalized Forward and layer SDN  data plane  match  control plane  action 4.2 What ’ s inside a router  OpenFlow examples of match-plus-action in 4.3 IP: Internet Protocol action  datagram format  fragmentation  IPv4 addressing  network address translation  IPv6 Network Layer: Data Plane 4-2

IPv6: motivation  initial motivation: 32-bit address space soon to be completely allocated.  additional motivation:  header format helps speed processing/forwarding  header changes to facilitate QoS IPv6 datagram format:  fixed-length 40 byte header  no fragmentation allowed Network Layer 4-3

IPv6 Design Issues  Overcome IPv4 scaling problem  lack of address space.  Flexible transition mechanism.  New routing capabilities.  Quality of service.  Security.  Ability to add features in the future.

Size of the Internet 6000 IPv4 Doomsday ? 5000 4000 3000 2000 1000 0 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 Theoretical Usable Allocated Addressable Network Layer 5 Distribution Statement A: Cleared for Public Release; Distribution is unlimited.

Internet BGP Routing Table Exponential Growth - CIDR breaking down CIDR deployment No Growth Linear Growth Exponential Growth http://www.telstra.net/ops/bgptable.html Network Layer 6 Distribution Statement A: Cleared for Public Release; Distribution is unlimited.

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What about technologies & efforts to slow the consumption rate?  Dial-access / PPP / DHCP  Provides temporary allocation aligned with actual endpoint use.  Strict allocation policies  Reduced allocation rates by policy of ‘current - need’ vs. previous policy based on ‘projected -maximum- size’.  CIDR  Aligns routing table size with needs-based address allocation policy. Additional enforced aggregation actually lowered routing table growth rate to linear for a few years.  NAT  Hides many nodes behind limited set of public addresses. Network Layer 10

What were the benefits?  Actual allocation history  1981 – IPv4 protocol published  1985 ~ 1/16 total space  1990 ~ 1/8 total space  1995 ~ 1/4 total space  2000 ~ 1/2 total space  The lifetime-extending efforts & technologies delivered the ability to absorb the dramatic growth in consumer demand during the late 90’s. In short they bought – TIME – Network Layer 11

Would increased use of NATs be adequate? NO!  NAT enforces a ‘client - server’ application model where the server has topological constraints.  They won’t work for peer -to- peer or devices that are “called” by others (e.g., IP phones)  They inhibit deployment of new applications and services, because all NATs in the path have to be upgraded BEFORE the application can be deployed.  NAT compromises the performance, robustness, and security of the Internet.  NAT increases complexity and reduces manageability of the local network.  Public address consumption is still rising even with current NAT deployments. Network Layer 12

IPv6 Background  IP has been patched (subnets, supernets) but there is still the fundamental 32 bit address limitation  IETF started effort to specify new version of IP in 1991  New version would require change of header  Include all modifications in one new protocol  Solicitation of suggestions from community  Result was IPng which became IPv6  First version completed in ’94  Same architectural principles as v4 – only bigger Network Layer 13

What Ever Happened to IPv5? 0 IP March 1977 version (deprecated) 1 IP January 1978 version (deprecated) 2 IP February 1978 version A (deprecated) 3 IP February 1978 version B (deprecated) 4 IPv4 September 1981 version (current widespread) 5 ST Stream Transport (not a new IP, little use) 6 IPv6 December 1998 version (formerly SIP, SIPP) 7 CATNIP IPng evaluation (formerly TP/IX; deprecated) 8 Pip IPng evaluation (deprecated) 9 TUBA IPng evaluation (deprecated) 10-15 unassigned Network Layer 14

IPv6 RFCs  1752 - Recommendations for the IP Next Generation Protocol  2460 - Overall specification  2373 - addressing structure  others (find them)  www.rfc-editor.org Network Layer 15

What were the goals of a new IP design?  Expectation of a resurgence of “always - on” technologies  xDSL, cable, Ethernet-to-the-home, Cell-phones, etc.  Expectation of new users with multiple devices.  China, India, etc. as new growth  Consumer appliances as network devices – (10 15 endpoints)  Expectation of millions of new networks.  Expanded competition and structured delegation. – (10 12 sites) Network Layer 16

Benefits of 128 bit Addresses  Room for many levels of structured hierarchy and routing aggregation  Easy address auto-configuration  Easier address management and delegation than IPv4  Ability to deploy end-to-end IPsec (NATs removed as unnecessary) Network Layer 17

Incidental Benefits of New Deployment  Chance to eliminate some complexity in IP header  improve per-hop processing  Chance to upgrade functionality  multicast, QoS, mobility  Chance to include new features  binding updates Network Layer 18

IPv6 Enhancements (1)  Expanded address space  128 bit  Improved option mechanism  Separate optional headers between IPv6 header and transport layer header  Most are not examined by intermediate routes • Improved speed and simplified router processing • Easier to extend options  Address autoconfiguration  Dynamic assignment of addresses Network Layer 19

IPv6 Enhancements (2)  Increased addressing flexibility  Anycast - delivered to one of a set of nodes  Improved scalability of multicast addresses  Support for resource allocation  Replaces type of service  Labeling of packets to particular traffic flow  Allows special handling  e.g. real time video Network Layer 20

Summary of Main IPv6 Benefits  Expanded addressing capabilities  Structured hierarchy to manage routing table growth  Serverless autoconfiguration and reconfiguration  Streamlined header format and flow identification  Improved support for options / extensions Network Layer 21

Address Complexity  IPv6 actually has many kinds of addresses  unicast, anycast, multicast,  link-local, site-local, loopback, IPv4-embedded, care-of, manually-assigned, DHCP-assigned, self-assigned, solicited- node, and more…  most of this complexity is also present in IPv4, just never written down in one place  a result of 20 years of protocol evolution  one simplification: no broadcast addresses in IPv6!  uses multicast to achieve same effects Network Layer 22

Types of address  Unicast  Single interface  Anycast  Set of interfaces (typically different nodes)  Delivered to any one interface  the “nearest”  Multicast  Set of interfaces  Delivered to all interfaces identified Network Layer 23

IPv6 Addresses  128 bits - written as eight 16-bit hex numbers. 5f1b:df00:ce3e:e200:0020:0800:2078:e3e3  High order bits determine the type of address. The book shows the breakdown of address types. Network Layer 24

Unicast Assignment in v6  Unicast address assignment is similar to CIDR  Unicast addresses start with 001  Host interfaces belong to subnets  Addresses are composed of a subnet prefix and a host identifier  Subnet prefix structure provides for aggregation into larger networks  Provider-based plan  Idea is that the Internet is global hierarchy of network  Three levels of hierarchy – region, provider, subscriber  Goal is to provide route aggregation to reduce BGP overhead • A provider can advertise a single prefix for all of its subscribers  Region = 13 bits, Provider = 24 bits, Subscriber = 16 bits, Host = 80 bits • Eg. 001,regionID,providerID,subscriberID,subnetID,intefaceID  What about multi-homed subscribers? • No simple solution  Anycase addresses are treated just like unicast addresses  It’s up to the routing system to determine which server is “closest” 25

IPv6 Addressing n bits m bits o bits p bits (125-m-n-o-p) bits 001 Registry ID Provider ID Subscriber ID Subnet ID Interface ID  Classless addressing/routing (similar to CIDR)  Notation: x:x:x:x:x:x:x:x (x = 16-bit hex number)  contiguous 0s are compressed: 47CD::A456:0124  IPv6 compatible IPv4 address: ::128.42.1.87  Address assignment  provider- based (can’t change provider easily)  geographic Network Layer 26

IPv6 Addressing 3 13 8 24 16 64 F TLA NLA Interface ID resv SLA Public Topology Site Topology  Top Level and Next Level Aggregators  Interface ID typically from MAC address  Special site-local and link-local addresses  Special multicast and anycast addresses  Special IPv4 compatible addresses

IPv4-Mapped IPv6 Address  IPv4-Mapped addresses allow a host that support both IPv4 and IPv6 to communicate with a host that supports only IPv4.  The IPv6 address is based completely on the IPv4 address. 28 Network Layer