資 管 lee lesson 2 introduction to ipv6. 資 管 lee lesson objectives limitations of ipv4 and...
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資 管 Lee
Lesson 2
Introduction to IPv6
資 管 Lee
Lesson Objectives
Limitations of IPv4 and modern day Internet
Features of IPv6Differences between IPv4 and IPv6IPv6 terminologyCase for IPv6 deployment
資 管 Lee
Limitations and some solutions of IPv4
Limitations ◦ Exponential growth since 1991◦ large routing tables◦ Need for simpler configuration◦ Requirement for security at the IP level◦ Need for better support for real-time delivery of data
—also called quality of service (QoS)
Possible solutions◦Class to classless (CIDR)◦Network Address Translation (NAT)◦Separated attached component: IPsecV4, IP
mobile, …
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Consequences of the Limited IPv4 Address Space: NATs
Internet
192.168.0.10
131.107.47.119 157.60.13.9
NAT
Host
Webserver
Dest. Addr.: 157.60.13.9Src. Addr.: 192.168.0.10Dest. TCP port: 80Src. TCP port: 1025
Dest. Addr.: 157.60.13.9Src. Addr.: 131.107.47.119Dest. TCP port: 80Src. TCP port: 5000
Dest. Addr.: 131.107.47.119Src. Addr.: 157.60.13.9Dest. TCP port: 5000Src. TCP port: 80
Dest. Addr.: 192.168.0.10Src. Addr.: 157.60.13.9Dest. TCP port: 1025Src. TCP port: 80
NAT
NAT
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NAT additional (NAT editors)
Problems with NAT added:◦TCP, UDP is stored elsewhere in the payload
E.g., FTP use PORT command with embedded IPv4 address
◦TCP or UDP is not used to identify the data stream Point-to-Point Tunneling Protocol (PPTP) use a
Generic Routing Encapsulation (GRE) and the Call ID field of the GRE identifies the data stream.
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NATs and Peer-to-Peer Applications
InternetNAT
Host A
Host B
Host C
Intranet
Host A can initiate a session with Host B and Host C However, Host A can not inform Host C of Host B.Modification is to make peer-to-peer application to be NAT-aware, And NAT itself.
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Features of IPv6New header formatLarge address spaceEfficient and hierarchical addressing
and routing infrastructureStateless and stateful address
configurationBuilt-in securityBetter support for QoSNew protocol for neighboring node
interactionExtensibility
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Differences Between IPv4 and IPv6 Feature IPv4 IPv6
Address length 32 bits 128 bits
IPSec support Optional Required
QoS support Some Better
Fragmentation Hosts and routers Hosts only
Packet size 576 bytes 1280 bytes
Checksum in header Yes No
Options in header Yes No
Link-layer address resolution ARP (broadcast) ARP (Group)
Multicast membership IGMP Multicast Listener Discovery (MLD)
Router Discovery Optional Required
Uses broadcasts Yes No
Configuration Manual, DHCP Automatic, DHCP
DNS name queries Uses A records Uses AAAA recordsDNS reverse queries Uses IN-ADDR.ARPA Uses IP6.INT
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IPv6 Terminology
Additional subnets
Router
Host
Neighbors
Host Host
Intra-subnetrouter
Bridge
LAN segment
Link
Subnet
Network
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Node, any device that runs IPv6 includes routers and hosts.
Link, one or more LAN segments bounded by routers
Subnet, one or more links that use the same 64-bit IPv6 address prefix. Also called network segment
Network, two or more subnets connected by routers
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Neighbors, nodes connected to the same link.
Interface, a physical or logical attachment of a node to a link
Link MTU: Max. Transfer UnitPath MTU
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The Case For IPv6 Deployment
IPv6 solves the address depletion problemIPv6 solves the international address
allocation problemIPv6 restores end-to-end communicationIPv6 uses scoped addresses and address
selectionIPv6 has more efficient forwardingIPv6 has built-in security and mobility
資 管 Lee
Review
Limitations of IPv4 and modern day Internet
Features of IPv6Differences between IPv4 and IPv6IPv6 terminologyCase for IPv6 deployment