Network Services and Telecommunications

Clemson Computing and Information Technology

Understanding IPv6

Dan SchmiedtCU Network Services & Telecommunications

Network Services and Telecommunications

Clemson Computing and Information Technology

What IS IPv6?

• What we currently use is IPv4.

• IP protocol 5 was the Stream protocol RFC1190.

• IPv6 is a Layer 3 protocol, just like IPv4 or IPX.

• What does that mean?

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The OSI Model: Secret Network Decoder Ring

Physical

Datalink

Network

Transport

Session

Presentation

Application

Fiber, Twisted Pair Copper, Radio

Ethernet, FDDI, ATM

IPv4, IPv6, IPX

TCP, UDP, SCTP, SPX

HTTP, SSH, Telnet, POP, IMAP

HTML

Firefox, Eudora, Etc

WDM, Hubs

Switches

Routers

Content Switches: A

CE, CSM, C

SS

Layer 1

Layer 2

Layer 3

Layer 4

Layer 5

Layer 6

Layer 7

Layer 8+ … People, Politics, etc

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Why IPv6? Another IPX? I have other things to worry about…

• IANA’s IPv4 address pool was exhausted on 31-Jan-2011, with regional authorities’ (RIRs) space exhausting in about a year.

• IPv4 will not scale to a fully connected world, even with perfect allocation (not possible):

Number of Addresses in IPv4 4,294,967,296 World Population (2003 est.) 6,314,000,000 Number of Addresses in IPv6 340,282,366,920,938,463,463,374,607,431,768,211,456

We need an Internet Protocol that allows for unfettered connectivity from anywhere to anywhere, in any direction

…and IPv6 is the only boat we have…

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So what? Stuff still works.

• What does that really mean? Will IPv4 just stop working one day?

• No, but IPv4 addresses are not available for new things.

• If we want those new things to talk to us, and if we want to talk to them, IPv6 is the only way.

• China, etc?

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Yikes, so how do we “convert?”

• We don’t.• We simply begin operating in a “dual

stack” world.• Workstations and servers will have v4 and

v6 addresses.• DNS will resolve names to either A (v4) or

AAAA records (v6)• Will be mostly invisible to the user.

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Some interesting numbers …

• Number of addresses in 130.127/16: 65,536 (2^16)

• Number of addresses per typical subnet: 256 (2^8)

• Number of addresses CU’s v6 allocation: 19,342,813,113,834,066,795,298,816 (2^84)

• Number of addresses per subnet in v6: 18,446,744,073,709,551,616 (2^64)

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So … what’s one of these addresses look like?

• Since we now have to represent 128 bits, using dotted decimal octets would not be practical. I don’t know about you, but I think this would be unwieldy:

120.254.56.127.130.25.36.78.162.73.221.86.213.34.48.1

• So did everyone else, so that representation is not valid in IPv6….

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So … what’s one of these addresses look like?

• So, addresses are represented in hexadecimal, with the following rules:• Case-insensitive• Leading zeroes are optional• Successive fields of “0” can be represented as ::, but only once

in an address• Example:

• 2001:0000:4321:0000:0000:c2d2:b0b0:0123 can be represented as:• 2001:0:4321:0:0:c2d2:b0b0:123 and then further reduced to:• 2001:0:4321::c2d2:b0b0:123

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What’s up with the /44 and all?

• In an IP address, a prefix tells us about a range of addresses…

• In IPv4, we used the “subnet mask” to tell us what part represented the network…

• In IPv6, we just say how many bits of the address are the network part, like so:

• <address>/<prefix length>• 2620:103:a000:a001::1/64

The remainder is the node part of the address…

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Types of addresses …

• In IPv6, a network interface will have multiple IPv6 addresses.

• I’ll mention a few of the more common ones…

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Unicast: Link-local

• Used for local, non-routed communication.• Quasi-implemented in IPv4 169.254/16

scheme, RFC 3927, Apple and MS…• In IPv6, it’s simply the prefix fe80::

fe80:: 217:f2ff:fec8:e40b

• … Pre-pended to the interface identifier.• This address is used to receive router

advertisements, etc.

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Unicast: global unicast

• Used for communication on the Internet.• Uses the prefix 2000::/3.• At Clemson, on IPv4, we know this as 130.127.0.0/16 …

• At Clemson, on IPv6, this is 2620:103:A000::/44

So, our prefix (48 bits)…

2620:103:a000

Plus site subnets (16 bits)…

:a001:

Plus the host part (64 bits)…

217:f2ff:fec8:e40b

… Gives us a globally routable IPv6 address!!

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Permanent multicast addresses

FF01::1 All nodes on the interfaceFF02::1 All nodes on the linkFF01::2 All routers on the interfaceFF02::2 All routers on the linkFF05::2 All routers in the siteFF02::1:FFXX:XXXX Solicited node (next slides)

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Unicast: Other addresses…

• Unspecified…• Just like IPv4, all zeroes• Represented as ::

• Loopback• Used for a host to represent itself• ::1

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Other types of addresses:

• Unique Local addressing: Addresses start with FD• Similar to 192.168’s, 172.19’s, 10.’s• 6to4: starts with 2002, transitional, tunnels=bad.• NAT64: starts with 64:ff9b, embeds IPv4 address in

IPv6 address. Also transitional

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How are addresses assigned?

• Addresses can be assigned statically:

• … Or automatically via autoconf, RFC2462, a stateless automatic configuration mechanism…

• … Or dynamically via DHCPv6, RFC3315, a managed dynamic allocation system similar to the DHCP we know today.

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Interface identifier…

• The IEEE came up with a way to make a 64-bit “EUI-64 identifier” out of a 48-bit MAC address for automatic configuration.

00 17 f2 c8 e4 0b

00 17 f2 ff fe c8 e4 0b

02 17 f2 ff fe c8 e4 0b

000000X0 X= 0 if non-unique MAC adressX=1 if unique MAC address

0217:f2ff:fec8:e40b2620:103:a000:a001:

This can be used for the host part of an IPv6 address…Which is then combined with a prefix,

obtained via router advertisement …

To make a complete IPv6 address!(future MACs will be 64 bits)

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For Example…

:Take a look at my workstation’s wired interface:

Linklocal

Autoconfglobal

ScopeStatically configuredglobal

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So, how do I start using it?

• … the same way you use IPv4!

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Clemson Computing and Information Technology

Next Steps at Clemson

• Enable IPv6 on all CU network devices.• Enable IPv6-capable DNS.• Enable IPv6 on Server and Client

computers.• Insist that new applications be able to use

IPv6.• Clemson IPv6 “Task Force”