laforge-slides/2002/ipv6-ccc2002/ipv6-ccc2002.mgp

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IPv6 Introduction


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by

Harald Welte <laforge@rfc2460.org>

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IPv6 Introduction
What? Why?


	What is IPv6?

		Successor of currently used IP Version 4
		Specified 1995 in RFC 2460

	Why?

		Address space in IPv4 too small
		Routing tables too large

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IPv6 Introduction
Advantages


	Advantages

		stateless autoconfiguration
		multicast obligatory
		IPsec obligatory
		Mobile IP

		Address renumbering
		Multihoming
		Multiple address scopes
		smaller routing tables through aggregatable allocation

		simplified l3 header
			64bit aligned
			no checksum (l4 or l2)
			no fragmentation at router

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IPv6 Introduction
Disadvantages

	Disadvantages
		Not widely deployed yet
		In most cases access only possible using manual tunnel
		OS support not ideal in most cases
			W2k: IPv6 available from MSi
			Windows XP: IPv6 included
			Linux has support, but some flaws (no IPsec, ndisc not fully implemented, ...)
			*BSD: full support (KAME)
			Solaris: full support
		Application support not ideal in most cases
			not supported: postfix, current squid, inn, proftpd,
			supported: bind8/9, apache, openssh, xinetd, rsync, squid-2.5(CVS), exim, zmailer, sendmail, qmail, inn-2.4(CVS), zebra

		Conclusion: Circular dependencies
			no application support without OS support
			no good OS support without applications
			no wide deployment without applications
			no applications without deployment
			no deployment without applications

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IPv6 Introduction
Deployment


	Experimental (6bone)
		Experimental 6bone (3ffe::) has been active since 1995.
		Uses slightly different Addressing Architecture (RFC2471)

	Production (2001::)
		Initial TLA's and sub-TLA's assigned in Sept 2000
		Mostly used in education+research
		Some commercial ISP's in .de are offering production prefixes

	Why isn't IPv6 widely used yet?
		No immediate need in Europe / North America
		Big deployment cost at ISP's (Training, Routers, ..)

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IPv6 Introduction
Technical: Address Space

	IP Version 6 Addressing Architecture (RFC2373)
		Format prefix, variable length
			001: RFC2374 addresses, 1/8 of address space
			0000 001: Reserved for NSAP (1/128)
			0000 010: Reserved for IPX (1/128)
			1111 1110 10: link-local unicast addresses (1/1024)
			1111 1110 11: site-local unicast addresses (1/1024)
			1111 1111 flgs scop: multicast addresses
				flgs (0: well-known, 1:transient)
				scop (0: reserved, 1: node-local, 2: link-local, 5: site-local, 8: organization-local, e: global scope, f: reserved)

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IPv6 Introduction
Technical: Address Space

		Aggregatable Global Unicast Address Format (RFC2374)
			3bit FP (format prefix = 001)
			13bit TLA ID - Top-Level Aggregation ID
			13bit Sub-TLA - Sub-TLA Aggergation ID
			19bit NLA - Next-Level Aggregation ID
			16bit SLA - Site-Level Aggregation ID
			64bit Interface ID - derived from 48bit ethernet MAC
		Initial subTLA-Assignments
			2001:0000::/29 - 2001:01f8::/29 IANA
			2001:0200::/29 - 2001:03f8::/29 APNIC
			2001:0400::/29 - 2001:05f8::/29 ARIN
			2001:0600::/29 - 2001:07f8::/29 RIPE
		loopback ::1
		unspecified: ::0
		embedded ipv4
			IPv4-compatible address: 0::xxxx:xxxx
			IPv4-mapped IPv4 (IPv4 only node): 0::ffff:xxxx:xxxx
		anycast
			allocated from unicast addresses
			only subnet-router anycast address predefined (prefix::0000)


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IPv6 Introduction
Technical: Header

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   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |Version| Traffic Class |           Flow Label                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         Payload Length        |  Next Header  |   Hop Limit   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   +                         Source Address                        +
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   +                      Destination Address                      +
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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		4bit Version: 6
		8bit Traffic Class
		20bit Flow Label
		16bit Payload Length (incl. extension hdrs)
		8bit next header (same values like IPv4, RFC1700 et seq.)
		8bit hop limit (TTL)
		128bit source address
		128bit dest address
		extension headers:
			hop-by-hop options
			routing
			fragment
			destination options
			IPsec (AH/ESP)

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IPv6 Introduction
Technical: Layer 2 <-> Address mapping


	Ethernet: No more ARP, everything within ICMPv6
	No Broadcast, everything built using multicast.

	all-nodes multicast address ff02::1
	all-routers multicast address ff02::2


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IPv6 Introduction
Technical: Address Configuration


	router discovery
		routers periodically send router advertisements
		hosts can send router solicitation to explicitly request RADV

	prefix discovery
		router includes prefix(es) in ICMPv6 router advertisements
		other nodes receive prefix advertisements and derive their final address from prefix + EUI64 of MAC address

	neighbour discovery
		machines can discover it's neighbours without advertising router


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IPv6 Introduction
How to get connected

	In case of static IPv4 address
		SIT (ipv6-in-ipv4) tunnel possible
		http://www.join.uni-muenster.de/

	In case of dynamic IPv4 address
		ppp (ipv6 over ppp) tunnel (pptp, l2tp) possible
		sitctrl (linux <-> linux)
		atncp (*NIX), http://www.dhis.org/atncp/


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IPv6 Introduction
Further Reading

	http://www.ipv6-net.org/ (deutsches IPv6 forum)
	http://www.6bone.net/ (ipv6 testing backbone)
	http://www.freenet6.net/ (free tunnel broker)
	http://hs247.com/ (list of tunnel brokers)

	http://www.bieringer.de/ (ipv6 for linux)
	http://www.linux-ipv6.org/ (improved ipv6 for linux)
	http://www.kame.net/ (ipv6 for *BDS)
	http://www.join.uni-muenster.de/ (ipv6 at DFN/WiN)

	http://www.gnumonks.org/ (slides of this presentation)

	And of course, all relevant RFC's