IPv6 (RFC 2460) Expanded addressing capabilities (128 bits). Header - - PowerPoint PPT Presentation

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Mar 18, 2023 393 likes •510 views

IPv6 (RFC 2460) Expanded addressing capabilities (128 bits). Header format simplification. Improved support for extensions and options. Flow labeling capability. Authenitication and privacy capabilities. 18 UTD, CS 6390 Ravi

SLIDE 1

IPv6 (RFC 2460)

Expanded addressing capabilities (128 bits). Header format simplification. Improved support for extensions and options. Flow labeling capability. Authenitication and privacy capabilities.

UTD, CS 6390 Ravi Prakash 18

SLIDE 2

IPv6 Packet Format Traffic class: to assign priorities to packets (for differentiated services). Flow label: to label sequences of packets indicating special handling. Payload length: in octets (included extension headers). Next header: type of extension header (if any). Hop limit: replaces TTL.

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SLIDE 3

IPv6 Extension Headers

Recommended order of extension headers. Extension headers processed only in the order they appear in

the packet.

Hop-by-Hop option header immediately after IPv6 header. Only Hop-by-Hop options header processed by every node on

path from source to destination.

Other extension headers processed only by destination. Packet discarded and ICMP message sent to source if expected

header not found.

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SLIDE 4

IPv6 Extension Headers (contd.) Routing Header: similar to IPv4’s loose source and record route

ption.

Swap IPv6 destination address with next address in list.

Fragment Header: used by source to indicate fragmentation.

Intermediate routers not allowed to fragment packets. Destination expects to receive all fragments within

60 seconds of the first arriving fragment.

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SLIDE 5

IPv6 Packet Size Issues

MTU should be at least 1280 bytes. For links with smaller MTU, lower layer fragmentation and

reassembly required.

Path MTU discovery is recommended.

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SLIDE 6

IPv6 Stateless Address Autoconfiguration (RFC 2462)

Avoid manual configuration of nodes. Node generates its own addresses using:

– interface identifier created using locally available information, – subnet prefix advertised by router.

Interface IP address = subnet prefix + subnet unique interface

id.

Duplicate Address Detection performed to ensure uniqueness.

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SLIDE 7

Lifetime of Interface Addresses

Interface’s IP address has finite lifetime. On lifetime expiry:

– address binding becomes invalid. – address may be reassigned to another interface.

Preferred address: address can be used for communication

without restriction.

Deprecated address: invalidation of this address binding is

imminent.

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SLIDE 8

Stateless Autoconfiguration Protocol

1. Node generates link-local address for interface.
2. Node verifies the uniqueness of tentative link-local address.
3. Node obtains router advertisement and composes address.
4. Node refreshes address binding on subsequent advertisements.

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SLIDE 9

Generation of Link-Local Address

Use link-local prefix FE80::0. N-bit long interface id replaces right-most N bits of link-local

prefix.

Interface id may be interface’s link-layer address. Another alternative is 64-bit address based on EUI-64

identifiers.

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SLIDE 10

Verification of Uniqueness

Node sends Neighbor Solicitation message containing tentative

address as target.

Uniqueness guaranteed if no Neighbor Advertisement with

tentative address received in response.

Otherwise, manual configuration has to be done.

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SLIDE 11

Processing Router Advertisements

Node listens for router advertisement. Send Router Solicitations to all-routers multicast group to obtain

advertisements quickly.

Advertisements contain subnet prefix and lifetime. Generate address using prefix and interface id, provided

advertised lifetime is positive.

Subsequent advertisements can refresh binding or add to