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Cisco IOS IPv6 Configuration Library
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Start Here: Cisco IOS Software Release Specifics for IPv6 Features
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Implementing IPv6 Addressing and Basic Connectivity
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Implementing ADSL and Deploying Dial Access for IPv6
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Implementing Multiprotocol BGP for IPv6
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Implementing DHCP for IPv6
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Implementing EIGRP for IPv6
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Configuring First Hop Redundancy Protocols in IPv6
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Implementing IPSec in IPv6
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Implementing IS-IS for IPv6
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Managing Cisco IOS Applications over IPv6
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Implementing Mobile IPv6
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Implementing IPv6 over MPLS
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Implementing IPv6 VPN over MPLS (6VPE)
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Implementing IPv6 Multicast
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Implementing NAT-PT for IPv6
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Implementing NetFlow for IPv6
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Implementing OSPF for IPv6
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Implementing Policy-Based Routing for IPv6
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Implementing QoS for IPv6
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Implementing RIP for IPv6
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Implementing Static Routes for IPv6
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Implementing Traffic Filters and Firewalls for IPv6 Security
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Implementing Tunneling for IPv6
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Table Of Contents
Implementing Tunneling for IPv6
Prerequisites for Implementing Tunneling for IPv6
Restrictions for Implementing Tunneling for IPv6
Information About Implementing Tunneling for IPv6
IPv6 Manually Configured Tunnels
GRE/IPv4 Tunnel Support for IPv6 Traffic
GRE/CLNS Tunnel Support for IPv4 and IPv6 Packets
Automatic IPv4-Compatible IPv6 Tunnels
IPv6 IPSec Site-to-Site Protection Using Virtual Tunnel Interface
How to Implement Tunneling for IPv6
Configuring Manual IPv6 Tunnels
Configuring Automatic 6to4 Tunnels
Configuring IPv4-Compatible IPv6 Tunnels
Verifying IPv6 Tunnel Configuration and Operation
Configuration Examples for Implementing Tunneling for IPv6
Configuring Manual IPv6 Tunnels: Example
Configuring GRE Tunnels: Examples
Tunnel Destination Address for IPv6 Tunnel: Example
Configuring CTunnels in GRE mode to Carry IPv6 Packets in CLNS: Example
Configuring 6to4 Tunnels: Example
Configuring IPv4-Compatible IPv6 Tunnels: Example
Configuring ISATAP Tunnels: Example
Feature Information for Implementing Tunneling for IPv6
Implementing Tunneling for IPv6
First Published: June 7, 2001Last Updated: May 1, 2006This module describes how to configure overlay tunneling techniques used by the Cisco IOS software to support the transition from IPv4-only networks to integrated IPv4- and IPv6-based networks. Tunneling encapsulates IPv6 packets in IPv4 packets and uses the IPv4 network as a link-layer mechanism.
Finding Feature Information in This Module
Your Cisco IOS software release may not support all of the features documented in this module. To reach links to specific feature documentation in this module and to see a list of the releases in which each feature is supported, use the "Feature Information for Implementing Tunneling for IPv6" section or the "Start Here: Cisco IOS Software Release Specifics for IPv6 Features" document.
Finding Support Information for Platforms and Cisco IOS and Catalyst OS Software Images
Use Cisco Feature Navigator to find information about platform support and Cisco IOS and Catalyst OS software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.
Contents
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Prerequisites for Implementing Tunneling for IPv6
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Prerequisites for Implementing Tunneling for IPv6
This document assumes that you are familiar with IPv4. Refer to the publications referenced in the "Related Documents" section for IPv4 configuration and command reference information.
Restrictions for Implementing Tunneling for IPv6
In Cisco IOS Release 12.0(21)ST and Cisco IOS Release 12.0(22)S and earlier releases, the Cisco 12000 series gives a very low priority to the processing of IPv6 tunneled packets. Therefore, we strongly recommend that you limit the use of IPv6 tunnels on the Cisco 12000 series using these releases to topologies that sustain a low level of network traffic and require a minimal amount of process-switching resources. IPv6 manually configured tunnel traffic in Cisco IOS Release 12.0(23)S is processed in software on the CPU of the line card, instead of in the Route Processor (RP) in the Cisco 12000 router, resulting in enhanced performance.
Information About Implementing Tunneling for IPv6
To configure tunneling for IPv6, you need to understand the following concepts:
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Overlay Tunnels for IPv6
Overlay tunneling encapsulates IPv6 packets in IPv4 packets for delivery across an IPv4 infrastructure (a core network or the Internet). (See Figure 34.) By using overlay tunnels, you can communicate with isolated IPv6 networks without upgrading the IPv4 infrastructure between them. Overlay tunnels can be configured between border routers or between a border router and a host; however, both tunnel endpoints must support both the IPv4 and IPv6 protocol stacks. Cisco IOS IPv6 supports the following types of overlay tunneling mechanisms:
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Figure 34 Overlay Tunnels
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Use Table 24 to help you determine which type of tunnel you want to configure to carry IPv6 packets over an IPv4 network.
Individual tunnel types are discussed in detail in this document. We recommend that you review and understand the information about the specific tunnel type that you want to implement. When you are familiar with the type of tunnel you need, see Table 25 for a summary of the tunnel configuration parameters that you may find useful.
IPv6 Manually Configured Tunnels
A manually configured tunnel is equivalent to a permanent link between two IPv6 domains over an IPv4 backbone. The primary use is for stable connections that require regular secure communication between two edge routers or between an end system and an edge router, or for connection to remote IPv6 networks.
An IPv6 address is manually configured on a tunnel interface, and manually configured IPv4 addresses are assigned to the tunnel source and the tunnel destination. The host or router at each end of a configured tunnel must support both the IPv4 and IPv6 protocol stacks. Manually configured tunnels can be configured between border routers or between a border router and a host. Cisco Express Forwarding switching can be used for IPv6 manually configured tunnels, or Cisco Express Forwarding switching can be disabled if process switching is needed.
GRE/IPv4 Tunnel Support for IPv6 Traffic
IPv6 traffic can be carried over IPv4 GRE tunnels using the standard GRE tunneling technique that is designed to provide the services necessary to implement any standard point-to-point encapsulation scheme. As in IPv6 manually configured tunnels, GRE tunnels are links between two points, with a separate tunnel for each link. The tunnels are not tied to a specific passenger or transport protocol, but in this case carry IPv6 as the passenger protocol with the GRE as the carrier protocol and IPv4 or IPv6 as the transport protocol.
The primary use of GRE tunnels is for stable connections that require regular secure communication between two edge routers or between an edge router and an end system. The edge routers and the end systems must be dual-stack implementations.
GRE has a protocol field that identifies the passenger protocol. GRE tunnels allow Intermediate System-to-Intermediate System (IS-IS) or IPv6 to be specified as a passenger protocol, which allows both IS-IS and IPv6 traffic to run over the same tunnel. If GRE did not have a protocol field, it would be impossible to distinguish whether the tunnel was carrying IS-IS or IPv6 packets. The GRE protocol field is why it is desirable that you tunnel IS-IS and IPv6 inside GRE.
GRE/CLNS Tunnel Support for IPv4 and IPv6 Packets
GRE tunneling of IPv4 and IPv6 packets through CLNS networks enables Cisco CLNS Tunnels (CTunnels) to interoperate with networking equipment from other vendors. This feature provides compliance with RFC 3147.
The optional GRE services defined in header fields, such as checksums, keys, and sequencing, are not supported. Any packet received requesting such services will be dropped.
Refer to CLNS Support for GRE Tunneling of IPv4 and IPv6 Packets, Release 12.3(7)T for details about this feature, and Cisco IOS Network Protocols 3: ISO CLNS, Release 12.4 for information about CTunnels.
Automatic 6to4 Tunnels
An automatic 6to4 tunnel allows isolated IPv6 domains to be connected over an IPv4 network to remote IPv6 networks. The key difference between automatic 6to4 tunnels and manually configured tunnels is that the tunnel is not point-to-point; it is point-to-multipoint. In automatic 6to4 tunnels, routers are not configured in pairs because they treat the IPv4 infrastructure as a virtual nonbroadcast multiaccess (NBMA) link. The IPv4 address embedded in the IPv6 address is used to find the other end of the automatic tunnel.
An automatic 6to4 tunnel may be configured on a border router in an isolated IPv6 network, which creates a tunnel on a per-packet basis to a border router in another IPv6 network over an IPv4 infrastructure. The tunnel destination is determined by the IPv4 address of the border router extracted from the IPv6 address that starts with the prefix 2002::/16, where the format is 2002:border-router-IPv4-address::/48. Following the embedded IPv4 address are 16 bits that can be used to number networks within the site. The border router at each end of a 6to4 tunnel must support both the IPv4 and IPv6 protocol stacks. 6to4 tunnels are configured between border routers or between a border router and a host.
The simplest deployment scenario for 6to4 tunnels is to interconnect multiple IPv6 sites, each of which has at least one connection to a shared IPv4 network. This IPv4 network could be the global Internet or a corporate backbone. The key requirement is that each site have a globally unique IPv4 address; the Cisco IOS software uses this address to construct a globally unique 6to4/48 IPv6 prefix. As with other tunnel mechanisms, appropriate entries in a Domain Name System (DNS) that map between hostnames and IP addresses for both IPv4 and IPv6 allow the applications to choose the required address.
Automatic IPv4-Compatible IPv6 Tunnels
Automatic IPv4-compatible tunnels use IPv4-compatible IPv6 addresses. IPv4-compatible IPv6 addresses are IPv6 unicast addresses that have zeros in the high-order 96 bits of the address, and an IPv4 address in the low-order 32 bits. They can be written as 0:0:0:0:0:0:A.B.C.D or ::A.B.C.D, where "A.B.C.D" represents the embedded IPv4 address.
The tunnel destination is automatically determined by the IPv4 address in the low-order 32 bits of IPv4-compatible IPv6 addresses. The host or router at each end of an IPv4-compatible tunnel must support both the IPv4 and IPv6 protocol stacks. IPv4-compatible tunnels can be configured between border-routers or between a border-router and a host. Using IPv4-compatible tunnels is an easy method to create tunnels for IPv6 over IPv4, but the technique does not scale for large networks.
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ISATAP Tunnels
ISATAP is an automatic overlay tunneling mechanism that uses the underlying IPv4 network as a NBMA link layer for IPv6. ISATAP is designed for transporting IPv6 packets within a site where a native IPv6 infrastructure is not yet available; for example, when sparse IPv6 hosts are deployed for testing. ISATAP tunnels allow individual IPv4 or IPv6 dual-stack hosts within a site to communicate with other such hosts on the same virtual link, basically creating an IPv6 network using the IPv4 infrastructure.
The ISATAP router provides standard router advertisement network configuration support for the ISATAP site. This feature allows clients to automatically configure themselves as they would do if they were connected to an Ethernet. It can also be configured to provide connectivity out of the site. ISATAP uses a well-defined IPv6 address format composed of any unicast IPv6 prefix (/64), which can be link local, or global (including 6to4 prefixes), enabling IPv6 routing locally or on the Internet. The IPv4 address is encoded in the last 32 bits of the IPv6 address, enabling automatic IPv6-in-IPv4 tunneling.
Although the ISATAP tunneling mechanism is similar to other automatic tunneling mechanisms, such as IPv6 6to4 tunneling, ISATAP is designed for transporting IPv6 packets within a site, not between sites.
ISATAP uses unicast addresses that include a 64-bit IPv6 prefix and a 64-bit interface identifier. The interface identifier is created in modified EUI-64 format in which the first 32 bits contain the value 000:5EFE to indicate that the address is an IPv6 ISATAP address. Table 26 describes an ISATAP address format.
Table 26 IPv6 ISATAP Address Format
link local or global IPv6 unicast prefix
0000:5EFE
IPv4 address of the ISATAP link
As shown in Table 26, an ISATAP address consists of an IPv6 prefix and the ISATAP interface identifier. This interface identifier includes the IPv4 address of the underlying IPv4 link. The following example shows what an actual ISATAP address would look like if the prefix is 2001:0DB8:1234:5678::/64 and the embedded IPv4 address is 10.173.129.8. In the ISATAP address, the IPv4 address is expressed in hexadecimal as 0AAD:8108.
Example:
2001:0DB8:1234:5678:0000:5EFE:0AAD:8108
IPv6 IPSec Site-to-Site Protection Using Virtual Tunnel Interface
The IPv6 IPSec feature provides IPv6 crypto site-to-site protection of all types of IPv6 unicast and multicast traffic using native IPSec IPv6 encapsulation. The IPSec virtual tunnel interface (VTI) feature provides this function, using IKE as the management protocol.
An IPSec VTI supports native IPSec tunneling and includes most of the properties of a physical interface. The IPSec VTI alleviates the need to apply crypto maps to multiple interfaces and provides a routable interface.
The IPSec VTI allows IPv6 routers to work as security gateways, establish IPSec tunnels between other security gateway routers, and provide crypto IPSec protection for traffic from internal network when being transmitting across the public IPv6 Internet.
For further information on VTIs, see the Implementing IPSec on IPv6 module.
How to Implement Tunneling for IPv6
The following sections explain how to implement tunneling for IPv6:
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Configuring Manual IPv6 Tunnels
This task explains how to configure a IPv6 overlay tunnel manually.
Prerequisites
With manually configured IPv6 tunnels, an IPv6 address is configured on a tunnel interface, and manually configured IPv4 addresses are assigned to the tunnel source and the tunnel destination. The host or router at each end of a configured tunnel must support both the IPv4 and IPv6 protocol stacks.
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What to Do Next
Proceed to the "Verifying IPv6 Tunnel Configuration and Operation" section.
Configuring GRE IPv6 Tunnels
This task explains how to configure a GRE tunnel on an IPv6 network. GRE tunnels can be configured to run over an IPv6 network layer and to transport IPv6 packets in IPv6 tunnels and IPv4 packets in IPv6 tunnels.
Prerequisites
When GRE IPv6 tunnels are configured, IPv6 addresses are assigned to the tunnel source and the tunnel destination. The tunnel interface can have either IPv4 or IPv6 addresses assigned (this is not shown in the task). The host or router at each end of a configured tunnel must support both the IPv4 and IPv6 protocol stacks.
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What to Do Next
Proceed to the "Verifying IPv6 Tunnel Configuration and Operation" section.
Configuring Automatic 6to4 Tunnels
This task explains how to configure a 6to4 overlay tunnel.
Prerequisites
With 6to4 tunnels, the tunnel destination is determined by the border router IPv4 address, which is concatenated to the prefix 2002::/16 in the format 2002:border-router-IPv4-address::/48. The border router at each end of a 6to4 tunnel must support both the IPv4 and IPv6 protocol stacks.
Restrictions
The configuration of only one IPv4-compatible tunnel and one 6to4 IPv6 tunnel is supported on a router. If you choose to configure both of those tunnel types on the same router, we strongly recommend that they do not share the same tunnel source.
The reason that a 6to4 tunnel and an IPv4-compatible tunnel cannot share an interface is that both of them are NBMA "point-to-multipoint" access links and only the tunnel source can be used to reorder the packets from a multiplexed packet stream into a single packet stream for an incoming interface. So when a packet with an IPv4 protocol type of 41 arrives on an interface, that packet is mapped to an IPv6 tunnel interface based on the IPv4 address. However, if both the 6to4 tunnel and the IPv4-compatible tunnel share the same source interface, the router is not able to determine the IPv6 tunnel interface to which it should assign the incoming packet.
IPv6 manually configured tunnels can share the same source interface because a manual tunnel is a "point-to-point" link, and both the IPv4 source and IPv4 destination of the tunnel are defined.
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Proceed to the "Verifying IPv6 Tunnel Configuration and Operation" section.
Configuring IPv4-Compatible IPv6 Tunnels
This task explains how to configure an IPv4-compatible IPv6 overlay tunnel.
Prerequisites
With an IPv4-compatible tunnel, the tunnel destination is automatically determined by the IPv4 address in the low-order 32 bits of IPv4-compatible IPv6 addresses. The host or router at each end of an IPv4-compatible tunnel must support both the IPv4 and IPv6 protocol stacks.
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Proceed to the "Verifying IPv6 Tunnel Configuration and Operation" section.
Configuring ISATAP Tunnels
This task describes how to configure an ISATAP overlay tunnel.
Prerequisites
The tunnel source command used in the configuration of an ISATAP tunnel must point to an interface with an IPv4 address configured. The ISATAP IPv6 address and prefix (or prefixes) advertised are configured as for a native IPv6 interface. The IPv6 tunnel interface must be configured with a modified EUI-64 address because the last 32 bits in the interface identifier are constructed using the IPv4 tunnel source address.
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Proceed to the "Verifying IPv6 Tunnel Configuration and Operation" section.
Verifying IPv6 Tunnel Configuration and Operation
This optional task explains how to verify IPv6 tunnel configuration and operation. The commands contained in the task steps can be used in any sequence and may need to be repeated.
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Examples
This section provides the following output examples:
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Sample Output for the show interfaces tunnel Command
This example uses a generic example suitable for both IPv6 manually configured tunnels and IPv6 over IPv4 GRE tunnels. In the example, two routers are configured to be endpoints of a tunnel. Router A has Ethernet interface 0/0 configured as tunnel interface 0 with an IPv4 address of 10.0.0.1 and an IPv6 prefix of 2001:0DB8:1111:2222::1/64. Router B has Ethernet interface 0/0 configured as tunnel interface 1 with an IPv4 address of 10.0.0.2 and an IPv6 prefix of 2001:0DB8:1111:2222::2/64. To verify that the tunnel source and destination addresses are configured, use the show interfaces tunnel command on Router A.
RouterA# show interfaces tunnel 0Tunnel0 is up, line protocol is upHardware is TunnelMTU 1514 bytes, BW 9 Kbit, DLY 500000 usec,reliability 255/255, txload 1/255, rxload 1/255Encapsulation TUNNEL, loopback not setKeepalive not setTunnel source 10.0.0.1 (Ethernet0/0), destination 10.0.0.2, fastswitch TTL 255Tunnel protocol/transport GRE/IP, key disabled, sequencing disabledTunnel TTL 255Checksumming of packets disabled, fast tunneling enabledLast input 00:00:14, output 00:00:04, output hang neverLast clearing of "show interface" counters neverInput queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0Queueing strategy: fifoOutput queue :0/0 (size/max)5 minute input rate 0 bits/sec, 0 packets/sec5 minute output rate 0 bits/sec, 0 packets/sec4 packets input, 352 bytes, 0 no bufferReceived 0 broadcasts, 0 runts, 0 giants, 0 throttles0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort8 packets output, 704 bytes, 0 underruns0 output errors, 0 collisions, 0 interface resets0 output buffer failures, 0 output buffers swapped outSample Output for the ping Command
To check that the local endpoint is configured and working, use the ping command on Router A:
RouterA# ping 2001:0DB8:1111:2222::2Type escape sequence to abort.Sending 5, 100-byte ICMP Echos to 2001:0DB8:1111:2222::2, timeout is 2 seconds:!!!!!Success rate is 100 percent (5/5), round-trip min/avg/max = 20/20/20 msSample Output for the show ip route Command
To check that a route exists to the remote endpoint address, use the show ip route command:
RouterA# show ip route 10.0.0.2Routing entry for 10.0.0.0/24Known via "connected", distance 0, metric 0 (connected, via interface)Routing Descriptor Blocks:* directly connected, via Ethernet0/0Route metric is 0, traffic share count is 1Sample Output for the ping Command
To check that the remote endpoint address is reachable, use the ping command on Router A.
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RouterA# ping 10.0.0.2Type escape sequence to abort.Sending 5, 100-byte ICMP Echos to 10.0.0.2, timeout is 2 seconds:!!!!!Success rate is 100 percent (5/5), round-trip min/avg/max = 20/21/28 msTo check that the remote IPv6 tunnel endpoint is reachable, use the ping command again on Router A. The same note on filtering also applies to this example.
RouterA# ping 1::2Type escape sequence to abort.Sending 5, 100-byte ICMP Echos to 1::2, timeout is 2 seconds:!!!!!Success rate is 100 percent (5/5), round-trip min/avg/max = 20/20/20 msThese steps may be repeated at the other endpoint of the tunnel.
Configuration Examples for Implementing Tunneling for IPv6
This section provides the following configuration examples:
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Configuring Manual IPv6 Tunnels: Example
The following example configures a manual IPv6 tunnel between router A and router B. In the example, tunnel interface 0 for both router A and router B is manually configured with a global IPv6 address. The tunnel source and destination addresses are also manually configured.
Router A Configuration
interface ethernet 0ip address 192.168.99.1 255.255.255.0interface tunnel 0ipv6 address 3ffe:b00:c18:1::3/127tunnel source ethernet 0tunnel destination 192.168.30.1tunnel mode ipv6ipRouter B Configuration
interface ethernet 0ip address 192.168.30.1 255.255.255.0interface tunnel 0ipv6 address 3ffe:b00:c18:1::2/127tunnel source ethernet 0tunnel destination 192.168.99.1tunnel mode ipv6ipConfiguring GRE Tunnels: Examples
The following example configures a GRE tunnel running both IS-IS and IPv6 traffic between router A and router B:
Router A Configuration
ipv6 unicast-routingclns routing!interface tunnel 0no ip addressipv6 address 2001:0DB8:1111:2222::1/64ipv6 router isistunnel source Ethernet 0/0tunnel destination 10.0.0.2tunnel mode gre ipv6!interface Ethernet0/0ip address 10.0.0.1 255.255.255.0!router isisnet 49.0000.0000.000a.00Router B Configuration
ipv6 unicast-routingclns routing!interface tunnel 0no ip addressipv6 address 2001:0DB8:1111:2222::2/64ipv6 router isistunnel source Ethernet 0/0tunnel destination 10.0.0.1tunnel mode gre ipv6!interface Ethernet0/0ip address 10.0.0.2 255.255.255.0!router isisnet 49.0000.0000.000b.00address-family ipv6redistribute staticexit-address-familyTunnel Destination Address for IPv6 Tunnel: Example
The following example shows how to configure the tunnel destination address for GRE tunneling of IPv6 packets:
Router(config)# interface Tunnel0Router(config-if)# no ip addressRouter(config-if)# ipv6 router isisRouter(config-if)# tunnel source Ethernet 0/0Router(config-if)# tunnel destination 2001:0DB8:1111:2222::1/64Router(config-if)# tunnel mode gre ipv6Router(config-if)# exit!Router(config)# interface Ethernet0/0Router(config-if)# ip address 10.0.0.1 255.255.255.0Router(config-if)# exit!Router(config)# ipv6 unicast-routingRouter(config)# router isisRouter(config)# net 49.0000.0000.000a.00Configuring CTunnels in GRE mode to Carry IPv6 Packets in CLNS: Example
The following example configures a GRE CTunnel running both IS-IS and IPv6 traffic between router A and router B in a CLNS network. The ctunnel mode gre command allows tunneling between Cisco and third-party networking devices and carries both IPv4 and IPv6 traffic.
The ctunnel mode gre command provides a method of tunneling compliant with RFC 3147 and should allow tunneling between Cisco equipment and third-party networking devices.
Router A
ipv6 unicast-routingclns routinginterface ctunnel 102ipv6 address 2001:0DB8:1111:2222::1/64ctunnel destination 49.0001.2222.2222.2222.00ctunnel mode greinterface Ethernet0/1clns router isisrouter isisnet 49.0001.1111.1111.1111.00Router B
ipv6 unicast-routingclns routinginterface ctunnel 201ipv6 address 2001:0DB8:1111:2222::2/64ctunnel destination 49.0001.1111.1111.1111.00ctunnel mode greinterface Ethernet0/1clns router isisrouter isisnet 49.0001.2222.2222.2222.00To turn off the GRE mode and restore the CTunnel to the default Cisco encapsulation routing only between endpoints on Cisco equipment, use either the no ctunnel mode command or the ctunnel mode cisco command. The following example shows the same configuration modified to transport only IPv4 traffic.
Configuring 6to4 Tunnels: Example
The following example configures a 6to4 tunnel on a border router in an isolated IPv6 network. The IPv4 address is 192.168.99.1, which translates to the IPv6 prefix of 2002:c0a8:6301::/48. The IPv6 prefix is subnetted into 2002:c0a8:6301::/64 for the tunnel interface: 2002:c0a8:6301:1::/64 for the first IPv6 network, and 2002:c0a8:6301:2::/64 for the second IPv6 network. The static route ensures that any other traffic for the IPv6 prefix 2002::/16 is directed to tunnel interface 0 for automatic tunneling.
interface Ethernet0description IPv4 uplinkip address 192.168.99.1 255.255.255.0!interface Ethernet1description IPv6 local network 1ipv6 address 2002:c0a8:6301:1::1/64!interface Ethernet2description IPv6 local network 2ipv6 address 2002:c0a8:6301:2::1/64!interface Tunnel0description IPv6 uplinkno ip addressipv6 address 2002:c0a8:6301::1/64
