Introduction to IPv6

ECE4110

Problems with IPv4

• 32-bit addresses give about 4,000,000 addresses• IPv4 Addresses WILL run out at some point– Some predicted by 2008, obviously did not happen– NAT has helped slow the rate of exhaustion for

addresses, but does not solve the problem completely.• Rapid increase in routing tables as network grows• Variable size header (20 bytes fixed + options)• Options have limited use due to limited size

IPv6 History

• RFC 2460, Basic Protocol 1998• RFC 2553, IPv6 Socket API, 2003• RFC 3775, Mobile IPv6, 2004• RFC 3697, Flow Label Specifications, 2004• RFC 4291, Address Architecture, 2006

IPv6 Timeline

http://www.nanog.org/mtg-0302/ppt/hain.pdf

IPv6 Features

• New, fixed size header format• Large Address Space (about 10^38 addresses)• Better Support for Hierarchical Addressing– Smaller routing tables?

• Automatic “link-local” address assignment• Includes IPSec (Secure IP) Support• Neighbor Discovery• Extension Headers• Multicast• Quality of Service

IPv6 Address

Network part Host part

managed by organization

0 12864

MAC

Subnet address used by the organization(fixed length)

IPv6 Address notation

• Basic rules– “:” in every 2 bytes– Hex digits

• shorthand– heading 0s in each block can be omitted– “0000” → “0”– “0:all zeros in between :0” can be “::”

IPv6 address notation – example

• 3ffe:0501:0008:0000:0260:97ff:fe40:efab– 3ffe:501:8:0:260:97ff:fe40:efab– 3ffe:501:8::260:97ff:fe40:feab

• ff02:0000:0000:0000:0000:0000:0000:0001– ff02:0:0:0:0:0:0:1– ff02::1

Types of addresses1st 4bits of the adddress Use0 (0000) Special address

1 (0001) Special address

2 (0010) Aggregatable global unicast address

3 (0011) Aggregatable global unicast address

4 (0100) Unassigned5 (0101) Unassigned6 (0110) Unassigned7 (0111) Unassigned8 (1000) Unassigned9 (1001) Unassigneda (1010) Unassignedb (1011) Unassignedc (1100) Unassignedd (1101) Unassignede (1110) link-local, site-local, multicast

f (1111) link-local, site-local,multicast

Aggregatable global unicast address

0 16byte82 4 6 10 12 14

0 128bit6432 96

TLA NLA Interface identifierSLA

TLA – Top Level Aggregator … assigned for 8K major providers(13+3bits)

NLA – Next Level Aggregator … assigned for smaller providers

SLA – Site Level Aggregator … subnet numbers within organizations (16bits)

NLA1

NLA2

NLA3

IPv6 Header Format

Ver6 Prio Flow Label

Hop LimitPayload Length Next Header

Source Address

Destination Address

IPv6 Extension Headers

• Hop-by-Hop Options– Every router on the path must examine and process

• Routing Options– Similar to source routing in IPv4

• Fragment Header• Destination Options Header

– Options processed at destination node only• Authentication Header

– Checksumming• Encapsulating Security Payload (ESP)

– Remainder of packet is encrypted

Show IPv6 Sockets Example