Internet Protocol Version 6 Specifications Chris Theodoridis Craig Young

Background – IPv4 Problems Internet Assigned Numbers Authority Concerned About Internet Growth IPv4 Provides 32-bits for Addressing Approximately 4 billion host addresses No Quality of Service Provisions in IPv4 IPv4 Provides No Means For Authentication or Integrity Checking Craig

Current Remedies for IPv4 Address Limitations: NAT – Network Address Translation CIDR – Classless InterDomain Routing Authentication/Message Integrity Handled by Upper-Layer Protocols QoS IPv4 is Designed to be Best-Effort Chris

IPv6 Enhancements 128-bit Addresses Streamlined 40 byte Header Enough for Every Grain of Sand to Have an IP address! Streamlined 40 byte Header Intended to Compensate JUMBO addresses Options have been Removed From Main Header “Flow” Labeling In the future, “Flows” could address issues related to packet scheduling and QoS Internet Layer Support for Authentication/Data Integrity & Privacy Craig

IPv6 Header Format IPv6 packet may carry 0, 1, or more extension headers These headers only examined by node identified by destination address field One exception is Hop-by-Hop Options Header Specified by value 0 in Next Header field of IPv6 header Must be examined in order presented Chris

Extensible Headers Hop-By-Hop Options Routing (Type 0) Fragment Destination Options Authentication Encapsulating Security Payload Chris

What is a ‘Flow’? RFC 2460 Loosely Defines “Flow” Packets In a Traffic Flow are Grouped “Flow” Concept Anticipates Future Needs of the Internet Protocol Handling For: Real-Time Service Non-Default QoS Craig

Upper-Layer Consideration Checksum Issues Maximum Packet Lifetime Maximum Upper-Layer Payload Size Responding to IPv6 Packets Craig

Upper-Layer Checksum Issues Increased Address Size TCP Uses Info from IP Layer in Checksum IPv6 Node Must Compute Checksum Under IPv4 UDP Doesn’t Have Checksum Craig

Maximum Packet Lifetime IPv4 Used Time-To-Live (TTL) IPv6 Renames TTL “Hop Limit” Max Lifetime Mechanism Must Exist in Upper-Layer How might this Impact End to End Communication? Craig

Maximum Upper-Layer Payload Increased Header Size TCP MSS Will Be Smaller TCP Over IPv4: MSS = Max Packet Size – 20 B Min Header TCP Over IPv6 MSS = Max Packet Size – 40 B Fixed Header Craig

Reverse Routing How to Create a Reverse Route? Routing Header Information must be Verified Use Local Configuration Use of Route Header Reversal Limited When Sender is Verified Craig

Transition from IPv4 to IPv6 IPv6-capable systems can be made backward-compatible to facilitate transition Does not address IPv4-capable systems handling IPv6 datagrams. Two proposed solutions: Dual-Stack Approach Tunnel Approach Chris

Dual-Stack Approach Chris http://www.cs.ucdavis.edu/~aksoy/course/s05/Lectures/network(4).pdf (slide #33)

Tunneling Approach Chris http://www.cs.ucdavis.edu/~aksoy/course/s05/Lectures/network(4).pdf (slide #34)

Related Work ICMPv6 – RFC 2463 IP Encapsulating Security Protocol (ESP) – RFC 2406 Craig

Critique Is a 128-bit address overkill? 340 Undecillion Addresses!!!! Should NAT (or similar) be used more? Will Traffic Classes be implemented better than TOS was? The Internet was designed to be updated at the Application Layer Chris

Questions ?