IPv6 The New Internet Protocol Integrated Network Services Almerindo Graziano.
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Transcript of IPv6 The New Internet Protocol Integrated Network Services Almerindo Graziano.
IPv6The New Internet Protocol
Integrated Network Services
Almerindo Graziano
Introduction
• Justification for IPv6
• IPv6 goals
• IPv6 Addressing
• The new Header– Extension Headers
• Recap
Justification for IPv6: What is wrong with IPv4?
• Wasteful of address space
• Not built-in support for hierarchical addressing– Subnetting– CIDR
• Large routing tables
• Large administrative workload:– Changing ISP– Merger or acquisition Renumbering
orNAT
What is wrong with IPv4?
• Routers perform a lot of operations– Table lookup– Options– Checksum– Fragmentation
• Lack of authentication– IP spoofing
• Lack of encryption
IPv6 goals• Support for a larger number of addresses• Reduce the size of routing tables• Simplify the protocol (easier to process)• Provide better security• Better support for Quality of Service• Provide support for mobile users• Allow the protocol to be extensible• Be compatible
IPv6 Addressing scheme
• Designed to be highly scalable and hierarchical• 16-byte long
– 7x1023 IP addresses per square meter!!!
– It “eliminates” the need for private address space
• IPv6 notation8000:0000:0000:0000:0123:8219:E42A:DF3E
8000::123:8219:E42A:DF3E
• IPv4 addresses can be written as::192.31.20.46
Address Allocation• IPv6 could support a number of diverse addressing
schemes– Provider Allocation
hierarchy is based on large service providers,regardless of their location
– Geographic Allocationhierarchy is based on the location of subscribers(similar to the telephony system)
• Both approaches have drawbacksLarge networks do not often conform to providerand/or geographical boundaries!!
Aggregation Based Allocation• Combines provider and geographic allocation
approaches– Based on the existence of limited number of
high-level exchange points• Large providers are represented at one or more
exchange points (provider orientation)
– Exchanges are distributed around the globe (geographic orientation)
• Favoured by the IETF
IPv6 Address Hierarchy
To other TLA
Long-Haul Provider
Interexchange(TLA)
Subscriber
Provider
Subscriber Subscriber
Subscriber
Provider
Subscriber
Long-Haul Provider
Long-Haul Provider
Long-Haul Provider
TLA: Top Level Aggregator
Aggregation-based Allocation• First 3 bits identify the type of address
– unicast, multicast, anycast etc..
• International registries assign block to TLA• TLA allocate block of addresses to NLA
– NLA can be large providers or global corporate networks
• NLA can create their own hierarchy
001 TLA RES NLA SLA Interface ID
3 13 8 24 bits 16 bits 64 bits
Public Topology Local InterfaceSiteTopology
IEEE EUI-64 Address24 bits - Company ID40 bits - interface ID
NLA 1
NLA 2
NLA 3
Site SLA Interface ID
Site SLA Interface ID
Site SLA Interface ID
32 bits
Aggregation-based Allocation
Other Address Types
• Site-Local Addresses– Similar to IPv4 private addresses
• Link-Local Addresses– A router doesn’t exist– Operate over a single link– Used for temporary bootstrapping
Not propagated outside organizational boundaries
Not allocated by public registry authorities
1111111010 00 . …. 00 Interface ID
128 bits
54 bits 64 bits10 bits
Other Address Types
• Multicast Addresses– Logical addresses to communicate to multiple
nodes
• Anycast Addresses– Used to communicate to the closest of a class of
nodes (closest DNS, closest router)– Allocated from the same address space as
Unicast addresses
Address Autoconfiguration• A node combines its MAC address with a network
prefix it learns from a neighbouring router• The autoconfiguration doesn’t need a manually
configured server: stateless address autoconfiguration– It differs from IPv4’s DHCP (stateful address
configuration). DHCPv6 has been developed
– Great advantage when an enterprise is forced to renumber because of an ISP change or M&A
– Great support for mobile users and dynamic workgroups
32 bits
Source Address
Destination Address
Version Priority Flow Label
Payload Length Next Header
Hop Limit
IPv4 Header IPv6 HeaderHeader Comparison
Version Type ofService
IHL Total Length
Identification Flag FragmentOffset
TTL Protocol Header Checksum
Source Address
Destination Address
Options Padding
32 bits
IPv4 Header = 14 fields
IPv6 Header = 8 fields
The new Header• Fixed size
• Fewer fields
• No Checksum– Already performed by other layers– Reliable networks
• Extension Headers replace Options– Routers can skip over some extension headers
Faster processing
Extensible
QoS Support• Priority field (4 bits)
– Congestion-Controlled traffic (0-7)• Traffic where the source backs off in case of congestion (e.g.
TCP)
– Non-Congestion-Controlled traffic (8-15)• Traffic where constant data rate and delay are desirable (real-
time audio/video)
• Flow label field (20 bits)– A sequence of packets sent from a particular source to a
particular destination for which the source desires special handling by intervening routers
Extension Headers Hop-by-Hop options header Destination options header-1 Source Routing header Fragmentation header Authentication header IPv6 Encryption header Destination options header-2
Extention Headers
• Hop-by-Hop– Carries information for all intermediate nodes– Used for management and debugging
• Destination– Carries information to be read just by
destination nodes
• Source Routing– Allows to specify a list of router to traverse
Fragmentation Header
• Each source is responsible for sending packets of the right size– MTU path discovery process
• Packet fragmentation is not permitted by intermediate nodes (routers)– Faster processing
• If fragmentation is required, the fragmentation header is used
Authentication Header
• It gives network applications a guarantee that a packet did in fact come from an authentic source
• A checksum is created based on the key and the content of the packet
• The checksum is re-run at the destination and validated
IPv6 Encryption Header
• Encapsulation Security Payload (ESP)– It provides encryption at the network layer
• Two encryption modes are supported– Transport mode– Tunnel mode (steel pipe)
Encryption modes
IPv6Header
ExtentionHeaders
ESP HeaderTransport Headerand Payload
Unencrypted Encrypted
IPv6Header
ExtentionHeaders
ESP Header
IPv6Header
ExtentionHeaders
Transport Headerand Payload
Unencrypted Encrypted
Original IP packet
Transport Mode
Tunnel Mode
The Transition to IPv6
• IPv6 offers a robust future-oriented solution to integrate physical networks
• Possibly use NAT but– can be a bottleneck
– prevents the use of IP-level security
– breaks Domain Name Servers
• 6Bone– Experimental world-wide network for testing IPv6
IPv6 Resources
– Main IPv6 pagehttp://ipv6.com/
– 6Bone home pagehttp://6bone.net/
– The case for IPv6 (Internet Draft) http://www.6bone.net/misc/case-for-ipv6.html