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Internet Protocol
version 6
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Outline
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Background
IPv6 Structure
Transition from IPv4 to IPv6
Example IPv6 Client / Server
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IPv4
• Developed – 1981
– Internet Size: 200 – 300 hosts
• Internet Grew
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1985 - about 1000 computers
1990 - about 100,000 – 2,000,000
1995 - about 10,000,000 – 45,000,000
2000 - about 100,000,000 – 400,000,000
2005 - about 325,000,000 – 1,000,000,000
2010 - ? – 2,000,000,000 – 5,000,000,000
The Motivation for Change
• Large growth by Asian Carriers
• 200 million addresses allocated in first 8 months of 2010
• Many addresses inefficiently allocated
• Intermediate sites (~500 – 1000 hosts) require class B
address (64k addresses)
• Addresses projected to run out (9/2011)
• www.potaroo.net/tools/ipv4/index.html
• US government required to convert by September
2012
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The Hourglass Model
© 2009 Pearson Education Inc., Upper Saddle River, NJ. All rights reserved.
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Intermediate Changes
• Private IPv4 addresses and NAT
– 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16
• Classless Interdomain Routing (CIDR)
– Remove the address class limitation
• DHCP
– Share addresses within a network
• Carrier Grade NAT
– Use NAT at carrier level.
IPv6 Goals
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Support lots (~billions) of hosts
Reduce the size of routing tables
Simplify the routing protocol
Provide better security
Support QoS
Improve multi-casting
Support host roaming (w/o changing address)
Support future protocol expansion / evolution
Coexist with IPv4
IPv6 Features
• Header Format – very different from IPv4
• Extension Headers
• IPv6 encodes information into separate headers
• A datagram consists of the base IPv6 header followed by zero or more
extension headers, followed by data
• Support for Real-Time Traffic
• a mechanism exists that allows a sender and receiver to establish a
high-quality path and to associate datagrams with that path,
intended for audio / video, but can also be used for cost sensitive
routing
• Extensible Protocol
• IPv6 allows a sender to add additional information to a datagram
• The extension scheme makes IPv6 more flexible than IPv4
• and means that new features can be added to the design as needed
© 2009 Pearson Education Inc., Upper Saddle River, NJ. All rights reserved.
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IPv6 Datagram Format
© 2009 Pearson Education Inc., Upper Saddle River, NJ. All rights reserved.
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IPv6 Base Header Format
• Although it is twice as large as an IPv4
header, the IPv6 base header contains less
fields
• Figure 24.3 (below) illustrates the format
© 2009 Pearson Education Inc., Upper Saddle River, NJ. All rights reserved.
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IPv6 Base Header Format
• VERS ( Version 6)
• TRAFFIC CLASS (DS + ECN)
• Differentiated services (6 bits) to specify general characteristics
that the datagram needs
• For example, to send interactive traffic (e.g., keystrokes/mouse), one
might specify a class that has low latency
• To send real-time audio across the Internet, a sender might request a
path with low jitter
• Explicit Congestion Notification (2 bits)
• PAYLOAD LENGTH
• Specifies only the size of the data being carried (i.e., the payload)
• Size of the header is excluded
© 2009 Pearson Education Inc., Upper Saddle River, NJ. All rights reserved.
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IPv6 Base Header Format
• HOP LIMIT
• Corresponds to the IPv4 TIME-TO-LIVE field
• Field FLOW LABEL
• Intended to associate a datagram with a particular path
• NEXT HEADER
• Used to specify the type of information that follows the current
header
• If the datagram includes an extension header
• NEXT HEADER field specifies the type of the extension header
• If no extension header exists
• NEXT HEADER field specifies the type of data being carried in the
payload
© 2009 Pearson Education Inc., Upper Saddle River, NJ. All rights reserved.
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IPv6 Flow Label
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Flow represents a sequence of packets from one source to
one (unicast, anycast, multicast) destination with special
handling requriements for the intermediate routers.
• Could be a single TCP connection or multiple connections
(think FTP)
• Special handling conditions must be set up prior to flow
commencement
• Intermediate Router rules
– Routers that do not support flow labeling must set the field to 0 on
originating packets and pass the field unchanged for forwarded
packets
– All packets that share the same flow label must have the same
source addr, destination addr, hop-by-hop options and router header
options (if used)
– Source assigns the flow label. All labels are pseudo-random
numbers between 1 and 220 -1. Zero label is reserved for no flow
label use.
IPv6 Base Header Format
© 2009 Pearson Education Inc., Upper Saddle River, NJ. All rights reserved.
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Implicit and Explicit Header Size
• No ambiguity about the interpretation of the NEXT HEADER
• the standard specifies a unique value for each possible header
• A receiver processes headers sequentially
• NEXT HEADER field in each header to determine what follows
• Some header types have a fixed size
• For example, a base header has a fixed size of exactly 40 octets
• Some extension headers do not have a fixed size
• the header must contain sufficient information to allow IPv6 to determine
where the header ends
© 2009 Pearson Education Inc., Upper Saddle River, NJ. All rights reserved.
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Extension IPv6 Headers
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Hop-by-Hop Options header (protocol 0)
Destination Options header (protocol 60)
Routing header (protocol 43)
Fragment header (protocol 44)
Authentication header (protocol 51)
Encapsulating Security Payload header (protocol 50)
Multiple Extension Headers
• When multiple extension headers are used in an IPv6
packet, their order must be as follows:
• Basic IPv6 header
• Hop-by-Hop Options
• Destination Options (if the Routing header is used)
• Routing
• Fragment
• Authentication
• Encapsulating Security Payload
• Destination Options
• Upper-layer (TCP, UDP, ICMPv6, ...)
Fragmentation, Reassembly, and Path MTU
• Similarities with IPv4
• a prefix of the original datagram is copied into each fragment
• and the payload length is modified to be the length of the
fragment
• Differences from IPv4
• It does not include fields for fragmentation in the base header
• It places the fragment information in a separate fragment
extension header
• the presence of the header identifies the datagram as a fragment
• Fragmentation is managed at the source, NOT at intermediate
nodes
© 2009 Pearson Education Inc., Upper Saddle River, NJ. All rights reserved.
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Fragmentation, Reassembly, Path MTU
© 2009 Pearson Education Inc., Upper Saddle River, NJ. All rights reserved.
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IPv6 Address Format
• 128 bit colon hexidecimal notation
– 8 groups of 16 bits, separated by colons
– 2001:0DB8:0000:0000:0000:0000:FF00:0000
• Addresses can be abbreviated
– 2001:DB8:0:0:0:0:FF00:0
– 2001:0DB8::FF00:0000
– 2001:DB8::FF00:0
IPv6 Addressing
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IPv6 Address Types
Address Type
Range
Application
Aggregatable global
unicast
2000::/3
Host-to-Host communications;
same as IPv4 unicast
Multicast
FF00::/8
One-to-many and many-to-many;
same as IPv4 multicast
Anycast
Same as Unicast
App. Based (load balancing,
optimixing traffic, redundancy)
Link-local unicast
FE80::/10
Connected-link communications
Solicited-node
multicast
FF02::1:FF00:0/104
Neighbor solicitation
IPv6 Address Format
• Aggregatable Global Unicast Addresses
(2000::/3)
Global Prefix
Interface ID
48 bits
64 bits
001
16 bit
SLA or
Subnet ID
SLA: Site Local Aggregator
Aggregatable Global Unicast
Addresses
• 2001::/16
• 2002::/16
• 2003::/16 to
3FFD::/16
• 3FFE::/16
IPv6 Internet address
6to4 Transition Mechanism
Unassigned
6bone (legacy – dropped 2006)
IPv6 Address Format
• Link-local Address
zeros
MAC address
FE80:0000:0000:0000:0000: 0050:56C0:0001
• IPv4 Compatible IPv6 Addresses
zeros
0000:0000:0000:0000:
zeros
IPv4 address
134:193:123:234
IPv4 address
0000:0000:0000:0000: 0086:00C1:007B:00EA
IPv6 Address Format
• Multicast Addresses
FFLS :0000:0000:0000:
xxxx:xxxx:xxxx:xxxx
L: Lifetime (0 = Permanent, 1= Temporary)
S: Scope 0001 = Node (Interface)
0010 = Link
0011 = Subnet
0101 = Site (deprecated
1000 = Organization
1110 = Global
Anycast Addresses
• Use aggregatable global unicast
addresses
• Can use site-local o rlink-local addresses
• Reserved anycast address
– Unicast_prefix:0:0:0:0
IPv6 Special Addresses
• Loopback address
– 0:0:0:0:0:0:0:1
• Reserved request address
– 0:0:0:0:0:0:0:0
Solicited-node Multicast Addresses
• Used as a replacement for ARP function of
identifying MAC addr for IP addr.
• Used to test whether a proposed new IPv6
address is already assigned
• Format
– FF02:0:0:0:0:1:FFxx:xxxx /104
– Where xx:xxxx is least significant 24 bits of
IPv6 address.
IPv6 Address Autoconfiguration
• EUI-64 – globally unique address
– Use network prefix
– Use globally unique Interface ID
• Stateless Autoconfiguration
– Locally determined
• Stateful Autoconfiguration
– DHCPv6
IPv6 Address Autoconfiguration
• Extended Unique Identifier - 64 bit
– Use Network prefix (typically 48 bits)
2001:0DB8:001F:F123:
• Use SLA / subnet mask for 16 bits
– Use 48 bit MAC address as seed for 64 bit EUID
2001:0DB8:001F: F123: 0050:56FF:FEC0:0001
• Insert FFFF in the middle of the MAC addr.
• Insert FFFE in the middle of an EUI-64 addr.
– Preferred -
IPv6 Address Autoconfiguration
• Stateless Autoconfiguration Objectives:
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No manual configuration required
SOHO should not require a stateful server / router
Large site should not require an address server
Should support gradeful renumbering of sites
Router advertisements should support multiple
configuration methods
Stateless Autoconfiguration Process
• Host generates a link-local address for the interface
• Send Neighbor Solicitation msgs containing tentative
address to verify that the address isn’t being used
• If address is not unique, process stops
• If address is unique, host has connectivity
• Wait for router advertisement from router to determine
what kind of autoconfig to use (link-local, site-local, etc).
• May send Router Solicitations to the all-routers multicast
group to get a faster answer.
IPv6 Address Autoconfiguration
• Stateful Autoconfiguration – DHCPv6
– Client creates a link-local address
– Client communicates with a reserved link-scoped
multicast address (FF02::1:2) using UDP
– Four message exchange used to acquire initial IPv6
address (solicit, advertise, request, reply)
– Two message exchange used to update or renew
IPv6 address (solicit, reply)
Transition Strategies
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Do Nothing
Dual Stack
Large Scale NAT (LSN)
Dual Stack Lite (DSLite)
6to4 Transition
Dual Stack
• Best (most long-term) approach
• Requires IPv4 Addresses for all sites
ISP
IPv4 Network
Ipv4 channel
Host
Ipv6 channel
IPv6 Network
Large Scale NAT (LSN)
• AKA Carrier Grade NAT (NAT444)
• Utilizes IPv4 address space well
• Problems with incoming connections
ISP
IPv4 NAT
Host
IPv4 NAT
IPv4 Network
Endpoint Independent Mapping
• NAT (NAPT) must always translates a given
source address into the same outgoing address,
independent of the destination.
S: 192.168.10.25:80
D: 123.234.45.56:789
192.168.10.25
S: 192.168.10.25:80
D: 134.193.12.34:678
S: 72.56.99.125:123
D: 123.234.45.56:789
123.234.45.56
72.56.99.125
S: 72.56.99.125:123
D: 123.234.45.56:789
134.193.12.34
Client / Server with IPv6
• New Functions, structures, constants
– inet_pton( ) - instead of inet_addr( )
– inet_ntop( ) – instead of inet_ntoa( )
– struct sockaddr_in6 addr
– AF_INET6, PF_INET6
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Server6.cpp (TCP echo server)
#include <iostream>, <stdio.h>, <resolv.h>, etc.
#define BUFSIZE 100
using namespace std;
void error(char* msg, ...)
{
va_list ap;
va_start(ap, msg);
vprintf(msg, ap);
va_end(ap);
exit (1);
}cs423-cotter
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Server6.cpp (TCP echo server)
int main(int count, char *argv[])
{
int sd, portnum;
struct sockaddr_in6 addr;
int sent, size=sizeof(addr);
int client;
char buf[BUFSIZE];
if ( count == 2 )
portnum = atoi(argv[1]);
else
portnum = 1234;
bzero(&addr, sizeof(addr));
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Server6.cpp (TCP echo server)
if ( (sd = socket(PF_INET6, SOCK_STREAM, 0)) < 0 )
error("Socket failed. ");
addr.sin6_family = AF_INET6;
addr.sin6_port = htons(portnum);
if ( inet_pton(AF_INET6, "0::0", &addr.sin6_addr) == 0 )
error("Inet_pton failed ");
if ( bind(sd, (struct sockaddr *) &addr, sizeof(addr)) != 0 )
error("Bind6 failed ");
if ( listen(sd, 5) != 0 )
error("Connect failed. ");
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Server6.cpp (TCP echo server)
while (1)
{
client = accept(sd, (struct sockaddr *) &addr, (socklen_t *) &size);
cerr << "Connected to " << inet_ntop(AF_INET6, &addr.sin6_addr, buf,
BUFSIZE);
cerr << " port = " << ntohs(addr.sin6_port) << endl;
do {
recv (client, buf, BUFSIZE, 0);
sent = send(client, buf,strlen(buf) , 0);
cerr << "Server received: " << buf << endl;
}
while ( sent > 0 && strcmp(buf, "quit") != 0 );
close(client);
}
}
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client6.cpp (TCP echo client)
#include <iostream>, <stdio.h>, <resolv.h>, etc.
#define BUFSIZE 100
using namespace std;
void error(char* msg, ...)
{
va_list ap;
va_start(ap, msg);
vprintf(msg, ap);
va_end(ap);
exit (1);
}
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client6.cpp (TCP echo client)
int main(int count, char *argv[])
{
int sock, portnum;
struct sockaddr_in6 addr;
char buf[BUFSIZE];
if ( count == 3 )
portnum = atoi(argv[2]);
else
portnum = 1234;
memset (&addr, 0, sizeof(addr));
if ( (sock = socket(PF_INET6, SOCK_STREAM, 0)) < 0 )
error("Socket failed. ");
addr.sin6_family = AF_INET6;
addr.sin6_port = htons(portnum);
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client6.cpp (TCP echo client)
if ( inet_pton(AF_INET6, argv[1], &addr.sin6_addr) == 0 )
error("Inet_pton failed ");
if ( connect(sock, (struct sockaddr *) &addr, sizeof(addr)) != 0 )
error("Connect failed. ");
do {
memset (buf, 0, BUFSIZE);
cin.getline(buf, BUFSIZE -1);
send(sock, buf, strlen(buf)+1, 0);
memset (buf, 0, BUFSIZE);
recv(sock, buf, sizeof(buf), 0);
cout << " Reply = " << buf << endl;
}
while ( strcmp(buf, "quit") != 0 );
close(sock);
return 0;
}cs423-cotter
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Example: Client Side - Windows
C:\data\cs423_fs12\examples\IPv6\ipv6_client\Debug>ipv6_client.exe
2610:e0:a040:cdfd:210:4bff:fe2b:22c2 23456
We are using port 1377
This is a test
Reply = This is a test
This is only a test
Reply = This is only a test
If this was useful, it would say something
Reply = If this was useful, it would say something
quit
Reply = quit
C:\data\cs423_fs12\examples\IPv6\ipv6_client\Debug>
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Example: Server Side - Linux
[rcotter@kc-sce-450p2 IPv6]$ ./server6_v2 23456
Connected to 2610:e0:a040:cdfd:e46d:ebb2:2057:d582 port = 1377
Server received: This is a test
Server received: This is only a test
Server received: If this was useful, it would say something
Server received: quit
^C
[rcotter@kc-sce-450p2 IPv6]$
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References
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RFC 2460 – IPv6 Specification
RFC 2462 – IPv6 Stateless Address Autoconfig
RFC 3056 - Connection of IPv6 Domains via IPv4 Clouds
RFC3315 – DHCPv6
RFC 4443 – ICMP v6
RFC 4861 – Neighbor Discovery Protocol
RFC 2553 – Basic Socket Interface Extensions for IPv6
RFC 2292 – Advanced Sockets API for IPv6
Computer Networks and Internets – 5ed – Comer, Prentice Hall, 2009
CCIE Routing and Switching Certification Guide 4ed –
Odom, Healy, Donohue – Cisco Press, 2010
• Computer Networks 5ed – Tanenbaum, Wetherall –
Prentice hall, 2011
• Data and Computer Communications 9ed – Stallings –
Prentice Hall, 2011
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Summary
• IPv6 Needed SOON! Deployment much
slower than expected.
• IPv6 very different from IPv4
– Much more flexible
– More secure
– Less overhead for routers
• Interworking with IPv4 will be needed for a
long time.
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