Introduction to IPv6. Unit -2. Prepared By:- NITIN PANDYA Assistant Professor, SVBIT.

Transcription

1 Introduction to IPv6 Unit -2 Prepared By:- NITIN PANDYA Assistant Professor, SVBIT.

2 IP Network Addressing INTERNET world s largest public data network, doubling in size every nine months IPv4, defines a 32-bit address (4,294,967,296) IPv4 addresses available The first problem is concerned with the eventual depletion of the IP address space. Traditional model of classful addressing does not allow the address space to be used to its maximum potential. 2 NITIN PANDYA

3 Subnetting Example H H2 Sub-network Internet G Net mask All traffic to H H4 3 NITIN PANDYA Sub-network Subnet mask

4 Classful Addressing When IP was first standardized in Sep 1981, each system attached to the IP based Internet had to be assigned a unique 32-bit address The 32-bit IP addressing scheme involves a two level addressing hierarchy Network Number/Prefix Host Number 4 NITIN PANDYA

5 Features of IPv6 Larger Address Space Aggregation-based address hierarchy Efficient backbone routing Efficient and Extensible IP datagram Stateless Address Autoconfiguration Security (IPsec mandatory) Mobility 5 NITIN PANDYA

6 IPv6 Packet Format Version Traffic Class Flow Label Payload Lengtht Next Header Hop Limit SourceAddr (4 words) DestinationAddr (4 words) Options (variable number) Data 6 NITIN PANDYA

7 Version (4 bits) The constant 6 (bit sequence 0110). Traffic Class (8 bits) a) The 6 most-significant bits are used for DSCP(DiffServ Code Point), which is used to classify packets. b) The remaining two bits are used for ECN(explicit congestion network);priority values subdivide into ranges: traffic where source provides congestion control and non-congestion control traffic. Flow Label (20 bits) : shows the flow of real time service. Payload Length (16 bits) :The size of the payload in octets, including any extension headers. Next Header (8 bits) : contains the sequence number of next header Hop Limit (8 bits) : at every its value is decremented, when counter reaches 0 packet is discarded. the 7 NITIN PANDYA

8 Source Address (128 bits) The IPv6 address of the sending node. Destination Address (128 bits) The IPv6 address of the destination node(s).in order to increase performance, and since current link layer technology is assumed to provide sufficient error detection, the header has no checksum to protect it. 8 NITIN PANDYA

9 128-bit IPv6 Address 3FFE:085B:1F1F:0000:0000:0000:00A9: groups of 16-bit hexadecimal numbers separated by : Leading zeros can be removed 3FFE:85B:1F1F::A9:1234 :: = all zeros in one or more group of 16-bit hexadecimal numbers 9 NITIN PANDYA

10 Packet Format Details Simpler format than v4 Version = 6 Traffic class same as v4 ToS Treat all packets with the same Flow Label equally Support QoS and fair bandwidth allocation Payload length does not include header limits packets to 64KB There is a jumbogram option Hop limit = TTL field Next header combines options and protocol If there are no options then NextHeader is the protocol field Options are extension header that follow IP header Ordered list of tuples 6 common types Quickly enable a router to tell if the options are meant for it Eg. routing, fragmentation, authentication encryption 10 NITIN PANDYA

11 Transition from v4 to v6 Dual stack operation v6 nodes run in both v4 and v6 modes and use version field to decide which stack to use Nodes can be assigned a v4 compatible v6 address Allows a host which supports v6 to talk v6 even if local routers only speak v4 Signals the need for tunneling Add 96 0 s (zero-extending) to a 32-bit v4 address eg. :: Nodes can be assigned a v4 mapped v6 address Allows a host which supports both v6 and v4 to communicate with a v4 hosts Add 2 bytes of 1 s to v4 address then zero-extend the rest eg. ::ffff: Tunneling is used to deal with networks where v4 router(s) sit between two v6 routers Simply encapsulate v6 packets and all of their information in v4 packets until you hit the next v6 router 11 NITIN PANDYA

12 IPv6 Provider Edge Router in Dual Stack 2001:0620:: v6 BGP sessions v6 2001:0420:: v4 6PE P P 6PE v6 2001:0421:: Dual Stack IPv4-IPv6 routers Dual Stack IPv4-IPv6 routers 2001:0621:: v6 v4 CE CE 6PE P IPv4 P 6PE CE v IPv4 Core Infrastructure is used as a part of IPv6 PEs are updated to support Dual Stack IPv6 reachability exchanged among 6PEs via BGP IPv6 packets transported from 6PE to 6PE inside subnet 12 NITIN PANDYA

13 Tunneling Computer networks use a tunneling protocol when one network protocol (the delivery protocol) encapsulates a different payload protocol. By using tunneling one can (for example) carry a payload over an incompatible deliverynetwork, or provide a secure path through an untrusted network. Tunneling typically contrasts with a layered protocol model such as those of OSI or TCP/IP. The delivery protocol usually (but not always) operates at a higher level in the model than does the payload protocol, or at the same level. 13 NITIN PANDYA

14 14 NITIN PANDYA Manual Tunneling at router

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