Mecanismos de transicion pv6

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Transitions MechanismIPv6 to IPv4

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Edgardo ScrimagliaCCIEedgardo.scrimaglia@avanetworks.com.ar

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Objetives

• Describe transition mechanisms used by IPv6 network traffic to transit IPv4 networks.

• Describe how IPv6-over-IPv4 encapsulation (tunneling) works.

• Describe how NAT-PT works.

• Explain how to express IPv4 addresses in IPv6 format.

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Transition IPv4-to-IPv6

Transition richness means:

• No fixed day to convert; no need to convert all at once.

• Different transition mechanisms are available:

– Smooth integration of IPv4 and IPv6

– Use of dual stack or 6-to-4 tunnels

• Different compatibility mechanisms:

– IPv4 and IPv6 nodes can communicate

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Dual stack is an integration method where a node has “implementation and connectivity” to both an IPv4 and IPv6 network.

Dual Stack

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Example Cisco IOS Dual Stack

• If both IPv4 and IPv6 are configured on an interface, this interface is dual-stacked.

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Tunneling

Tunneling is an integration method where an IPv6 packet is encapsulated within another protocol, such as IPv4. This method of encapsulation is IPv4 protocol 41 (Excluding Teredo):

This includes a 20-byte IPv4 header with no options and an IPv6 header and payload.

This is considered dual stacking.

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“Isolated” Dual-Stack Host

Encapsulation can be done by edge routers between hosts or between a host and a router.

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Configuring an IPv6 Tunnel

• Configured tunnels require:

– Dual-stack endpoints

– IPv4 and IPv6 addresses configured at each end

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Example: Cisco IOS Tunnel Configuration6in4 Tunnel

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Configuring static routes for 6-to-4 tunnels

A 6-to-4 tunnel establishes a transient link between IPv6 domains which are connected by an IPv4 backbone

• Create a tunnel interface

• Set tunnel mode with the tunnel mode ipv6ip 6to4command

• Create an IPv6 specific address

• Set the source interface for the tunnel

• Configure an Ipv6 static route

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Converting IPv4 addresses to IPv6 for 6-to-4 Tunnel

• A 6-4 tunnel uses special addresses in the 2002::/16 address space

• The first 16 bits are the hexadecimal number 2002

• The next 32 bits are the original source address in hexadecimal form

• The IPv4 address of 172.16.12.1 is converted into AC10:0C01

• The complete address would be 2002:AC10:0c01:1::1/64

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Example: Cisco IOS Tunnel Configuration6-to-4 between R1 y R3

R1

R2 R3

Lo0 10.1.2.1/24Lo0 10.1.3.1/24

Lo0 10.1.1.1/24

172.16.12.1 /24 S0/0/0

S0/0/0 172.16.12.2 /24

S0/0/1 172.16.23.2 /24

172.16.23.1 /24 S0/0/1

R1R1(config-if)# interface tunnel 0R1(config-if)# tunnel mode 1pv6ip to 6to4R1(config-if)# ipv6 address 2002:AC10:0C01:1::1/64R1(config-if)# tunnel source s0/0/0ExitR1(config)# ipv6 route 2002::/16 tunnel 0

VerificationR1#ping 2002:AC10:1703:1::3R1#ping 2002:AC10:1703:1::100 Host IPV6 (remote)

R3R3(config-if)# interface tunnel 0R3(config-if)# tunnel mode 1pv6ip to 6to4R3(config-if)# ipv6 address 2002:AC10:1703:1::3/64R3(config-if)# tunnel source s0/0/1ExitR3(config)# ipv6 route 2002::/16 tunnel 0

VerificationR3#ping 2002:AC10:0c01:1::1R3#ping 2002:AC10:0c01:1::100 Host IPV6 (remote)

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IPV6 Net 2001:A:C:1::/64

IPV6 Host 2001:A:C:1::100

IPV6 Net 2001:A:B:1::/64

IPV6 Host 2001:A:B:1::100

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Cisco IOS Software Is IPv6-Ready: 6-to-4 Tunneling

• 6-to-4:

– Is an automatic tunnel method

– Gives a prefix to the attached IPv6 network

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NAT-Protocol Translation (NAT-PT) is a translation mechanism that sits between an IPv6 network and an IPv4 network.

The job of the translator is to translate IPv6 packets into IPv4 packets and vice versa.

Translation – NAT-PT

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Self Check

1. What are the 2 most common techniques to transition from IPv4 to IPv6?

2. How does a dual-stack node choose which stack to use for a particular traffic flow?

3. How is a router interface “dual-stacked”?

4. What is tunneling?

5. What is the job of the translator in a NAT-PT topology?

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Resumen

• The two most common techniques to transition from IPv4 to IPv6 are dual stack and IPv6-to-IPv4 (6-to-4) tunnels.

• Tunneling IPv6 traffic over an IPv4 network requires one edge router to encapsulate the IPv6 packet inside an IPv4 packet and another router to de-encapsulate it.

• Transition methods from IPv4 to IPv6 include dual-stack operation, protocol translation, and 6-to-4 tunnels.

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Q & A!!

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Resources

• Tunneling IPv6 through an IPv4 Network (Configuration Example)

– http://cisco.com/en/US/partner/tech/tk872/technologies_configuration_example09186a00800b49a5.shtml

• Implementing Tunneling for IPv6

– http://cisco.com/en/US/partner/products/sw/iosswrel/ps5187/products_configuration_guide_chapter09186a00801d6604.html

• Cisco IOS IPv6 Configuration Library

– http://cisco.com/en/US/partner/products/sw/iosswrel/ps5187/products_configuration_guide_book09186a00801d65f9.html

• Network Address Translator-Protocol Translator Technical Notes

– http://www.cisco.com/en/US/products/ps6553/products_data_sheet09186a008011ff51.html

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