Tik Network Application Frameworks. IPv6. Pekka Nikander Professor (acting) / Chief Scientist HUT/TML / Ericsson Research NomadicLab

Transcription

1 Pekka Nikander TKK/TML Tik Network Application Frameworks IPv6 Pekka Nikander Professor (acting) / Chief Scientist HUT/TML / Ericsson Research NomadicLab 1 Pekka.Nikander@hut.fi

2 Pekka Nikander TKK/TML Lecture outline 2 Differences to IPv4 Addressing and routing Extension headers Tackling IPv4 problems Mobility Autoconfiguration Upper layer pseudo headers Performance Security Fault Tolerance and Ad Hoc Summary

3 Pekka Nikander TKK/TML Differences to IPv bit addresses: uni-, any- and multicast Simpler basic IP header + optional extensions Better mobility support (no triangular routing) Autoconfiguration replaces basic DHCP IPSEC AH mandatory (ESP only optional) 6 QoS class Flow label Payload length Next hdr Hop Limit Src address (16 bytes) Dst address (16 bytes)

4 Pekka Nikander TKK/TML Addressing and routing bit hierarchical, 1080::8:800:200C:417A Only about 15% of address space used for temporary IPv4 migration / for NSAP / IPX 001 Aggregatable Global Unicast Address X Link-local / site local Multicast Differences to routing Looking up a route based on 128 bits vs 32 bits * Only 61 bits used for routing in practice, but anyway Æ Route lookup hardware must be updated

5 Pekka Nikander TKK/TML Extension headers IP header Extensions TCP/UDP Data 5 Hop-by-hop options: e.g. Jumbo Payload Routing (must be authenticated) Fragmentation Not at routers; path MTU discovery mandatory IPSEC AH and ESP Mobility Binding Update (must be authenticated) Destination options

6 Pekka Nikander TKK/TML Tackling IPv4 problems 6 Hosts don t need to know their routing prefixes Moving whole subnets easy Easier support for several parallel ISPs Host part in IP address allocated by autoconfig Also possible other solutions, e.g., manufacturer allocated address; conflicts resolved via autoconf ARP not always needed Physical layer address may be the host part * Policy decision; privacy issues must be addressed Physical address used for a link local address Reverse ARP never needed

7 Pekka Nikander TKK/TML Mobility 7 No triangular routing Home address destination option Binding req/upd/ack destination options No explicit foreign agent Any router able to function as a foreign agent Based on autoconfiguration Requires AH (or ESP) Binding update/acknowledge must be protected Requirements for all nodes Must understand home address option

8 Pekka Nikander TKK/TML Autoconfiguration Built-in feature Must be implemented by all devices ICMPv6 replaces basic DHCP functionality ICMPv6 used for assigning addresses DHCPv6 still used for e.g. DNS configuration 8 1. A booting host creates an tentative local identifier 2. The local identifier is used to create a link local address 3. The host starts to listen all-nodes multicast and solicitednode multicast groups 4. The host sends Neighbor Solicitation message(s) 5. If any other soliciation or adverticement is received, the identifier is duplicate and cannot be used

9 Pekka Nikander TKK/TML Upper layer pseudo headers A pseudo-header included in TCP/UDP checksum Rationale: SRC/DST addr part of socket identity IPv4 pseudo header Source address (4) Destination address (4) zero Protocol Upper layer length 9 IPv6 pseudo header Source Address (16) Destination Address (16) Upper layer packet length (4) zero Next hdr

10 Pekka Nikander TKK/TML Performance 10 Impacts on router performance unknown No large enough field tests or simulations Hardware / FPGA based header handling and route lookups must be updated Netmasks have greatly varying lengths Memory requirements grow by factor of 4.5? Minimum header size 40 instead of 20 bytes Mobile IPv6 adds another 20 bytes for each packet for home address destination option AH is to probable to be used widely, adding yet another bytes

11 Pekka Nikander TKK/TML Security IPSEC AH a mandatory feature ESP optional due to export restrictions Certain extension headers require authentication Routing extensions Mobility Binding update/acknowledgement Firewalls must be updated MIPv6 designed to work with firewalls ESP may render firewalls obsolete 11

12 Pekka Nikander TKK/TML Fault Tolerance and Ad Hoc Autoconfiguration increases fault tolerance Router discovery Less errors due to less manual configuration No address clashes (at least in theory) Basic ad hoc networking supposed to function Again mainly due to autoconfiguration No real ad hoc routing yet 12

13 Pekka Nikander TKK/TML Summary Classless hierarchical routing Basic security included Performance an open question Slightly better fault tolerance than IPv4 Supports basic ad hoc networking QoS support features included No need for NAT (at least in theory) 13

14 IPv4 / IPv6 interoperability Pekka Nikander Professor (acting) / Chief Scientist HUT/TML / Ericsson Research NomadicLab Pekka Nikander Stockholm

15 Presentation outline Motivation Transition proposals Basic dual stack (RFC1933) RFC SIIT NAT-PT AIIH DTI & Bump-in-dual-stack Summary IPSEC interoperability Recommendations Pekka Nikander Stockholm

16 Motivation Most of the Internet will continue to use IPv4 NAT has extended IPv4 life time Some computers will never be updated Most routers cannot be effectively upgraded L3 switches are hardware bound to protocol IPv6 offers a number of advances Thomas Eklund discussed these Many relevant to mobile hosts Somebody needs to be first Must assure interoperation with IPv4 Pekka Nikander Stockholm

17 Transition proposals IPv6 over IPv4 oriented Basic dual stack (RFC1933) RFC Interoperability oriented SIIT (Stateless IP/ICMP Translator) NAT-PT (NAT Protocol Translator) AIIH (Assignment of IPv6 to IPv6 Hosts) DTI & Bump-in-dual-stack (Dynamic Tunnel Interface) Pekka Nikander Stockholm

18 Basic dual stack (RFC1933) Completed April 1996 Dual stack hosts Full, independent IPv4 stack Full, independent IPv6 stack Two distinct address spaces May be interconnected or not Dual stack routers Same as hosts IPv6 over IPv4 tunneling Interconnection of isolated IPv6 clouds Host-to-host, host-to-router, router-to-router Pekka Nikander Stockholm

19 RFC draft-ietf-ngtrans-mech-02.txt, March 1999 Sun Microsystems & Freegate Corp. Clarifications Default sending algorithm changed Pure IPv4 not allowed btw IPv6 capable hosts New operating modes Disallows forwarding of decapsulated packets... Pekka Nikander Stockholm

20 SIIT Stateless IP/ICMP Translator draft-ietf-ngtrans-siit-05.txt, January 1999 Sun Microssystems Two-way translation of IP and ICMP headers No more absolutely necessary to use dual stack Does not allow IPv4 host to initiate connections IPv6 host IPv6 SIIT IPv4 IPv4 host Pekka Nikander Stockholm

21 NAT-PT Network Address Translation Protocol Transl. draft-ietf-ngtrans-natpt-05.txt BT, Lucent Same basic ideas as in SIIT Requires state in the translation gateway Includes the concept of Application Level GW Defined for DNS and FTP DNS to distribute IPv4 addresses for IPv6 hosts Pekka Nikander Stockholm

22 AIIH Assignment of IPv4 Global Addrs to IPv6 Hosts draft-ietf-ngtrans-assgn-ipv4-addrs-01.txt Compaq, Jan 1999 Alleviate the need of NAT on IPv6 side Combines DNS and DHCPv6 IPv4 host makes a DNS query IPv6 host is assinged a temp IPv4 address Corresponding IPv6 addr assigned via DHCP Also when IPv6 host connects to IPv4 Assumes dual stack, but can be used with SIIT Supports tunneling (don t ask details) Pekka Nikander Stockholm

23 DTI & Bump-in-dual-stack Dynamic Tunneling Interface draft-ietf-ngtrans-dti-00.txt, December 1998 ENST (France) Dual Stack Hosts using the "Bump-in-the-Stack" draft-ietf-ngtrans-dual-stack-hosts-00. Hitachi TCP/UDP IPv4 bumb IPv6 Tunnel endpoint IPv4 bumb IPv6 Standard IPv4 host Pekka Nikander Stockholm

24 Summary IPv6 IPv4 interoperability still under research IPv6 over IPv4 oriented proposals Basic dual stack (RFC1933) RFC Interoperability oriented proposals SIIT (Stateless IP/ICMP Translator) NAT-PT (NAT Protocol Translator) AIIH (Assignment of IPv4 to IPv6 Hosts) DTI & Bump-in-dual-stack (Dynamic Tunnel Interface) DNS tricks, tunneling, protocol translation Pekka Nikander Stockholm

25 IPSEC interoperability No problems at theoretical level AH cannot be used for obvious reasons ESP can be used in both transport and tunnel mode In fact, IPv4 over IPv6 tunnels could easily be ESP tunnels Pekka Nikander Stockholm

26 Recommendations To support legacy systems (Windows NT) Support DTI like dual stack Tunnel IPv4 over the IPv6 cloud Maybe use AIIH DNS/DHCPv6 to assign IPv4 addresses In new devices (e.g. Symbian) Use AIIH DNS to assign addresses Combine AIIH with SIIT so that no tunneling is needed Pekka Nikander Stockholm