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Engineering Workshops IPv6 “Under the Hood”. Engineering Workshops IPv6 Tutorial/Workshop Rick Summerhill Executive Director, Great Plains Network Dale.

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Presentation on theme: "Engineering Workshops IPv6 “Under the Hood”. Engineering Workshops IPv6 Tutorial/Workshop Rick Summerhill Executive Director, Great Plains Network Dale."— Presentation transcript:

1 Engineering Workshops IPv6 “Under the Hood”

2 Engineering Workshops IPv6 Tutorial/Workshop Rick Summerhill Executive Director, Great Plains Network Dale Finkelson University of Nebraska at Lincoln

3 Engineering Workshops Basic Headers IPv6 Header IPv4 Header

4 Engineering Workshops Basic Headers Fields –Version (4 bits) – only field to keep same position and name –Class (8 bits) – new field –Flow Label (20 bits) – new field –Payload Length (16 bits) – length of data, slightly different from total length –Next Header (8 bits) – type of the next header, new idea –Hop Limit (8 bits) – was time-to-live, renamed –Source address (128 bits) –Destination address (128 bits)

5 Engineering Workshops Basic Headers Simplifications –Fixed length of all fields, not like old options field – IHL, or header length irrelevant –Remove Header Checksum – rely on checksums at other layers –No hop-by-hop fragmentation – fragment offset irrelevant – MTU discovery –Add extension headers – next header type (sort of a protocol type, or replacement for options) –Basic Principle: Routers along the way should do minimal processing

6 Engineering Workshops Extension Headers Extension Header Types –Routing Header –Fragmentation Header –Hop-by-Hop Options Header –Destinations Options Header –Authentication Header –Encrypted Security Payload Header

7 Engineering Workshops Extension Headers Routing Header

8 Engineering Workshops Extension Headers General Routing Header

9 Engineering Workshops Extension Headers Fragmentation Header –“I thought we don’t fragment?” –Can do at the sending host –Insert fragment headers

10 Engineering Workshops Extension Headers Options Headers in General –The usual next header and length –Any options that might be defined

11 Engineering Workshops Extension Headers Destinations Options Header –Act – The Action to take if unknown option 00 – Skip Over 01 – Discard, no ICMP report 10 – Discard, send ICMP report even if multicast 11 – Discard, send ICMP report only if unicast –C – Can change in route –Number is the option number itself

12 Engineering Workshops Extension Headers Hop-by-Hop Extension Header –The usual format of an options header –An example is the jumbo packet Payload length encoded Can’t be less than 65,535 Can’t be used with fragmentation header

13 Engineering Workshops Extension Headers Extension Header Order –Hop-by-Hop options Header –Destination options Header (1) –Routing Header –Fragment Header –Authentication Header –Destination Options Header (2) –Upper Layer Header, e.g. TCP, UDP How do we know whether or not we have an upper layer header, or an extension header? –Both are combined into header types

14 Engineering Workshops Header Types Look in packet for next header –Can be Extension Header –Can be something like ICMP, TCP, UDP, or other normal types

15 Engineering Workshops Header Types DecimalKeywordHeader Type 0Reserved (IPv4) 0HBHHop-BY-Hop options (IPv6) 1ICMPInternet Control Message (IPv4) 2IGMPInternet Group Management (IPv4) 2ICMPInternet Control Message (IPv6) 3GGPGateway-to-Gateway Protocol 4IPIP in IP (IPv4 encapsulation) 5STStream 6TCPTransmission Control --- --------------------------------------- 17UDPUser Datagram

16 Engineering Workshops Header Types DecimalKeywordHeader Type 29ISO-TP4ISO Transport Protocol Class --- --------------------------------------- 43RHRouting Header (IPv6) 44FHFragmentation Header (IPv6) 45IDRPInter-domain Routing Protocol --- --------------------------------------- 51AHAuthentication Header 52ESPEncrypted Security Payload --- --------------------------------------- 59NULLNo next header (IPv6) --- ---------------------------------------

17 Engineering Workshops Header Types DecimalKeywordHeader Type 80ISOISO Internet Protocol (CLNP) --- --------------------------------------- 88IGRP 89OSPF --- --------------------------------------- 255Reserved

18 Engineering Workshops ICMP Completely Changed – note new header type Now includes IGMP Types organized as follows –1 – 4 Error messages –128 – 129 Ping –130 – 132 Group membership –133 – 137 Neighbor discovery General Format

19 Engineering Workshops ICMP TypeDescription 1Destination Unreachable 2Packet Too Big 3Time Exceeded 4Parameter Problem 128Echo Request 129Echo Reply 130Group Membership Query 131Group Membership Report 132Group Membership Reduction 133Router Solicitation 134Router Advertisement 135Neighbor Solicitation 136Neighbor Advertisement 137Redirect

20 Engineering Workshops ICMP Error Messages (Types 1 – 4) – Some Examples –Destination Unreachable Code 0 – No route to destination Code 1 – Can’t get to destination for adminstrative reasons Code 2 – Address unreachable Code 3 – Port Unreachable –Packet Too Big Code 0, Parameter is set to MTU of next hop Allows for MTU determination –General Format

21 Engineering Workshops ICMP Ping –Similar to IPv4 Echo Request, set code to 0 Echo Reply sent back –General Format

22 Engineering Workshops Multicast Multicast (and Anycast) built in from the Beginning –Scope more well-defined – 4 bit integer –Doesn’t influence well-defined groups ValueScope 0Reserved 1Node Local 2Link Local 5Site Local 8Organization Local EGlobal Local FReserved OthersUnassigned

23 Engineering Workshops Multicast A Few Well-Defined Groups –Note all begin with ff, the multicast addresses –Much of IGMP is from IPv4, but is in ICMP now ValueScope FF02::0Reserved FF02::1All Nodes Address FF02::2All Routers Address FF02::4DVMRP Routers FF02::5OSPF FF02::6OSPF Designated Routers FF02::9RIP Routers FF02::DAll PIM Routers ETC

24 Engineering Workshops Changes from IPv4 to IPv6 Expanded addressing capabilities Header format simplification Improved support for extensions and options Flow labelling capability Authentication and privacy capabilities


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