IPv6
Tarik Cicic
University of Oslo
December 2001
Overview
• New generation IP protocol (IPv6):
– why do we need it
– support for new Internet services
• discussion
2
Internet technology
Users
• Idea: exchange of
information between
remote systems
• all users, with their
individual needs, using
different applications, on
different systems and
various network
interconnects, must be
able to communicate!
e-mail
Web
TCP
voice
UDP
IP
3
ATM Ethernet
Functionality
1
Internet today: Problem list
•
•
•
•
•
Address space insufficient
traffic congestion implies waiting for all
network configuration and reconfiguration
lack of Quality of Service support
no built-in security mechanisms
The best solution to these problems is
provided through improving IP itself.
4
Internet 2 terminology
• IP or IPv4: internet protocol in use today
• IPv6: new generation internet protocol
(formerly called IPng), experimentally
deployed today
• Internet 2: experimental IP network.
Originally an American research project,
now also research project in Norway.
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IPv6: improvements
• The Internet (with IPv4) is a tremendous success
• IPv6 should inherit good features from IPv4, solve the
problems and add functionality:
–
–
–
–
–
–
huge address room, autoconfiguration
Quality of Service attributes
mobility through improved routing
security support
simplicity
extensibility
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2
IPv6 packets
• Addresses: 128 bit instead of 32
• IPv6 header is simpler than IPv4
• Quality of Service through priority field
and flow label
• optional parameters in “extension headers”
Fixed size Optional
Extension
headers
Header
Variable size
Payload
7
IPv6 vs. IPv4 header
IPv4
Version Hlen
TOS
Length
Ident
Flags
Offset
Protocol
TTL
Checksum
Source address
Destination address
Options (variable)
Pad (variable)
VersionTraffic Class
IPv6
Payload length
32 bit
Flow label
Next header Hop limit
Header has got
a fixed length
4 x 32 = 128 bit
Source address
4 x 32 = 128 bit
Destination address
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Addressing
• 128 bits give 3.4 1038 addresses (couple of
thousands per square meter of the Earth)
• this
– covers traditional needs ☺
– opens for new services
• geographical addressing
• hierarchical multicast etc.
• autoconfiguration of networking equipment
• anycast addresses
9
3
Extension headers
• All non-essential information is moved from the
IP header to the extension headers:
–
–
–
–
–
–
hop-by-hop header (per-hop processing)
destination options header
routing header (e.g. explicit route)
fragment header (if payload is larger than the MTU)
authentication header
encapsulating security payload header
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Quality of Service
•
•
QoS-friendliness achieved through the traffic
class and flow label fields
traffic class sample:
0 urgent network maintenance
2 CBR real-time service
3 VBR service
….
8 telnet
10 www
15 e-mail
•
•
IPv6 is not a resource reservation protocol!
flow label can be used11 in QoS routing
Mobile computing
• Destination address change is a challenge for
mobile computing based on IPv4
• routing extension header adds new functionality
• explicit routing:
– incoming packets with an explicit route should be
answered to with the inverse explicit route
– can move from net to net without breaking TCP
connections!
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4
Security
• Built-in authentication and privacy
mechanisms (by special headers)
• in IPv4, the security was left to higher level
protocols (applications, SSL)
• now every packet (even the addresses) can
be encrypted
• one cannot present himself as another user
• lower overhead, higher security than today.
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Transition mechanisms
• Smooth transition:
–
–
–
–
dual protocol stack
tunneling
name resolution (DNS)
Network Address Translation
• these mechanisms are in place today.
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… but when will it come?
• IPv6 is still not widely used:
– 4 billion addresses we have today is sufficient?
– new host and router software costs?
– no substantial improvements compared to IPv4?
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5
IPv4/v6 comparison
IPv6
Conclusion
Big, poorly
Address space
utilized
IPv4
Huge
CIDR and NAT can
extend IPv4 life
Header and
routing
complexity
Variable
size, much
to compute
Fixed,
simple
Routers are getting
faster, unclear
Mobility,
security
No support
Supported
There services can
be added to IPv4
Quality of
Service
No support No support
–
+
Tiny difference
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