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IPv6: The Next Generation Internet Protocol
CEOS WGISS 18: Beijing, China
September 2004
Dave Hartzell
Computer Sciences Corp, NASA Ames
Agenda
• What?
• Why?
• How?
• When?
• Where?
• Your role as a developer and user
What Is IPv6?
• Internet Protocol version 6 (IPv6) is the next generation Internet Protocol.
• It is designed to supplement IPv4 and fix problems with IPv4 and allow for future growth.– IPv4 is the IP protocol currently in use on the
Internet today.
Why IPv6?
• IPv6 primarily fixes the major problem we have with IPv4: Depletion of address space.
• IPv4 has a 32-bit address space. Each host on the Internet needs a legitimate, routable IPv4 address to communicate.
Current IPv4 Addressing
• But why is there a problem with IPv4 addressing?
232 = 4,294,967,296 addresses, right?
Wrong
• Unfortunately, IPv4 has many inefficiencies, and the 4 billion+ addresses were ineffectively allocated 30 years ago.
• “Class-full” Routing (per network/org):– Class A: 16 million 5.x.x.x 255.0.0.0– Class B: 65,536 hosts 150.150.x.x 255.255.0.0– Class C: 256 hosts 215.10.10.x 255.255.255.0
“Classes”• Class A
– 1.0.0.0 to 126.0.0.0 = only 126 class A’s– Taken by large companies (IBM, AT&T) and
universities (MIT) that didn’t need that much space.
• Class B– 128.0.x.x to 191.255.x.x– Given to Government agencies and universities and
Internet Service Providers (ISPs)
• Class C– 192.1.1.x to 223.255.255.x– Given to small business, universities and small ISPs
The “Other” Classes
• Class D:– 224.0.0.0 to 239.255.255.255– IPv4 Multicast– Probably wasted space
• Class E:– 240.0.0.0 to 247.255.255.255– ??? More wasted space
• 248.0.0.0 to 255.255.255.255 ? – I don’t know. “Future use”
The Point Is…
• Class-full routing may have seem like a good way to manage early IPv4 address space, but it could not keep up with demand.– So, in the mean-time, “Class-less” routing was adopted,
which dropped the Classes (A,B,C) from the hierarchy. • Classless allowed organizations like MIT, IBM, etc., to give
back space, while hanging on to most of the original used space.
Again, Why Do We Need v6?
• Given the allocation trends seen a few years ago, and with large, international networks being built, we were in danger of IPv4 address space exhaustion.
Current Internet Routing Table*
* Source: Geoff Houston
Historical and Future IPv4 Growth*
* Source: Geoff Houston
How Does v6 Work?
• IPv6 “addresses” this problem (pun intended) by increasing the address space from 32 bits to 128 bits.
• So…
2128 = 3.4 x 1038 addresses, right?
Well, not Quite, but Close
• IPv6 is set up to work with the last 64 bits of the address as the “host” address.– This usually maps to the hardware address, or
in the case of Ethernet, the MAC address.
v4 vs. v6
VersionIHL
Type of Service
Total Length
Identification FlagsFragment
Offset
Time to Live
Protocol Header Checksum
Source Address
Destination Address
Options Padding
Version
Traffic Class Flow Label
Payload LengthNext
HeaderHop Limit
Source Address
Destination AddressIPv4
IPv6
128 bits
32 bits
Aggregatable Global Unicast Addresses
• Aggregatable Global Unicast addresses are:–Addresses for generic use of IPv6–Structured as a hierarchy to keep the aggregation
• See RFC 3513• From Cisco
Interface IDGlobal Routing Prefix SLA
001
64 bits3 45 bits 16 bits
Provider Site Host
Other IPv6 Ranges
• Like IPv4, IPv6 has reserved ranges for applications like Multicast, Anycast, and Reserved.– But, there is still plenty of IPv6 space available.
IPv6 and Legacy Protocols
• The IPv6 standard does not modify any of the payload protocols like TCP or UDP.
• IPv6 can also translate or tunnel IPv4– or vice versa: IPv4 can tunnel IPv6
• 6to4 (RFC 3056) – WAN tunneling
• ISATAP (Draft) – Campus tunneling
6to4 and ISATAP Addresses
2002Public IPv4
address
/48 /64/16
Interface IDSLA
2001 0410
ISP prefix
Site prefix
/32 /48 /64
Registry
/23
IPv4 Host address00 00 5E FE
32 bits
32 bits
So When?
• Given all the development in the early to mid-’90s, the “demand” for IPv6 has stalled just a bit.
• It is still needed, especially when we start inter-networking devices like mobile phones, autos, PDAs, etc.
• The demand is there NOW, and so is the technology.
OK, So When?• Despite the demand, we’re not in that much danger
of running out of IPv4 addresses.• But, Asian and PacRim networks are having trouble
getting space and are leading the edge of IPv6 deployment.
• Best estimate is 2020 for current unallocated space, given recent and historical trends (G. Houston)– 2040 when you release the “reserved” spaces.
• My opinion: be cautious of these numbers. Demands can change, given new applications and networks.
Where?
• Most modern operating systems (OSes) have modern, stable IPv6 stacks– Windows 2000, XP– Mac OS X– Solaris 8, 9– Linux– Open, Free and Net BSDs
IPv4/IPv6 Routers
• Router vendors now support “dual-stack” routers, which can do IPv4 and IPv6 on the same interface– Cisco– Juniper– Everyone else who doesn’t have it, better do it
NOW.
Networks
• Most commercial ISPs (in the U.S.) do not offer IPv6.– They might offer “tunneled” IPv6.
• Most research and some government networks support IPv6 “natively”:– NASA’s NREN Research Network
• Not the NASA production Network– Internet2 (Abilene), vBNS+, CANARIE, DANTE
(GEANT), APAN?
Your Role As a User
• Most people are currently running OSes capable of IPv6.
• Most routers are IPv6 capable.
• But, ISPs and carriers might not be capable.– They need to be pressured into supporting IPv6.
• Your role as an end-user is limited.
Your Role As a Developer
• As a developer, make sure that when writing networked applications, your team plans ahead for IPv6.– Usually, all libraries support IPv6 and IPv4
address methods.
• Don’t get caught in a situation like the Y2K problem with IPv6!!! Make sure applications can handle IPv4 and IPv6.
Issues
• Security
• Performance (of stacks and applications)
• Adoption
• Transparency and migration
