mGRE Tunnel Support over IPv6

The mGRE Tunnel Support over IPv6 feature enables service providers to deploy IPv6 in their core infrastructure.

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Information About mGRE Tunnel Support over IPv6

mGRE Support over IPv6

Multiple sites of a Dynamic Multipoint Virtual Private Network (DMVPN) are interconnected by IPv6. A single logical multipoint generic routing encapsulation (mGRE) tunnel interface interconnects one VPN site to another. An IPv6 subnet connects a tunnel interface with other tunnel interfaces from various VPN sites. All tunnel interfaces connecting VPN sites act as hosts on the logical IPv6 subnet. This structure is referred to as the tunnel overlay network.

To enable service providers deploy IPv6 in their core infrastructure, mGRE tunnels over IPv6 are supported. DMVPN customers may run either IPv4 or IPv6 in their local networks, so the overlay endpoints can be either IPv4 or IPv6. For an IPv6 transport endpoint, the overlay endpoint can either be an IPv4 or IPv6 private network address.

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.

How to Configure mGRE Tunnel Support over IPv6

Configuring mGRE Tunnel Support over IPv6

Perform this task on the hub and spoke device of the multipoint generic routing encapsulation (mGRE) tunnel.

Before You Begin

Create a Next Hop Resolution Protocol (NHRP) ID to configure on a multipoint generic routing encapsulation (mGRE) tunnel.

For more information on configuring NHRP, see the “How to Configure NHRP” topic in the IP Addressing : NHRP Configuration Guide.

SUMMARY STEPS

    1.    enable

    2.    configure terminal

    3.    ipv6 unicast-routing

    4.    interface tunnel tunnel-number

    5.    description description-string

    6.    ipv6 address ip-address mask

    7.    ipv6 nhrp map mulitcast dynamic

    8.    ipv6 nhrp network-id network-id

    9.    ipv6 nhrp holdtime seconds

    10.    ipv6 nhrp nhs ipv6- nhs-address

    11.    tunnel source ip-address | ipv6-address | interface-type | interface-number

    12.    tunnel mode gre multipoint ipv6

    13.    end


DETAILED STEPS
     Command or ActionPurpose
    Step 1enable


    Example: 
    Device> enable
     

    Enables privileged EXEC mode.

    • Enter your password if prompted.
     
    Step 2configure terminal


    Example: 
    Device# configure terminal
     

    Enters global configuration mode.

     
    Step 3ipv6 unicast-routing


    Example: 
    Device(config)# ipv6 unicast-routing
     

    Enables forwarding of IPv6 unicast datagrams.

     
    Step 4interface tunnel tunnel-number


    Example: 
    Device(config)# interface tunnel 1
     

    Configures a tunnel interface and enters interface configuration mode.

    • The tunnel-number argument specifies the number of tunnel interfaces that you can create or configure. There is no limit on the number of tunnel interfaces that you can configure.

     
    Step 5description description-string


    Example: 
    Device(config-if)# description DMVPN HUB
     

    Configures information specific to the interface.

     
    Step 6ipv6 address ip-address mask


    Example: 
    Device(config-if)# ipv6 address 2001:0DB8:0C18:2::300/64
     

    Specifies the IPv6 address and mask of the hub.

     
    Step 7ipv6 nhrp map mulitcast dynamic


    Example: 
    Device(config-if)# ipv6 nhrp map multicast dynamic
     

    Enables NHRP to initiate multipoint GRE tunnels to register their unicast NHRP mappings.

     
    Step 8ipv6 nhrp network-id network-id


    Example: 
    Device(config-if)# ipv6 nhrp network-id 100
     

    Configures NHRP on an interface. The IPv6 NHRP network-id is a unique 32-bit network identifier from a nonbroadcast multiaccess (NBMA) network. The range is from 1 to 4294967295.

     
    Step 9ipv6 nhrp holdtime seconds


    Example: 
    Device(config-if)# ipv6 nhrp holdtime 100
     

    Configures the time in seconds that NBMA addresses are advertised as valid in NHRP response.

     
    Step 10ipv6 nhrp nhs ipv6- nhs-address


    Example: 
    Device(config-if)# ipv6 nhrp nhs 1101:1::1
     

    Specifies IPv6 prefix of one or more NHRP servers.

     
    Step 11tunnel source ip-address | ipv6-address | interface-type | interface-number


    Example: 
    Device(config-if)# tunnel source ethernet 0
     

    Configures the source address of a tunnel interface.

     
    Step 12tunnel mode gre multipoint ipv6


    Example: 
    Device(config-if)# tunnel mode gre multipoint ipv6
     

    Sets the encapsulation mode of the tunnel to mGRE IPv6.

     
    Step 13end


    Example: 
    Device(config-if)# end
     

    Exits to global configuration mode.

     
    What to Do Next

    Verify the mGRE tunnel over IPv6.

    Verifying mGRE Tunnel Support over IPv6

    The show commands can be entered in any order.

    Before You Begin

    Configure mGRE tunnel over IPv6.

    SUMMARY STEPS

      1.    show interface tunnel tunnel-interface

      2.    show tunnel endpoints tunnel tunnel-interface

      3.    show ipv6 traffic


    DETAILED STEPS
      Step 1   show interface tunnel tunnel-interface

      This command displays information about the tunnel.



      Example: 
      Device# show interface tunnel 1

Tunnel1 is up, line protocol is down
Hardware is Tunnel
Description: DMVPN Spoke 1
MTU 1456 bytes, BW 100 Kbit/sec, DLY 50000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation TUNNEL, loopback not set
Keepalive not set
Tunnel linestate evaluation down - transport reg down
Tunnel source Ethernet1/0
Tunnel Subblocks:
src-track:
Tunnel1 source tracking subblock associated with Ethernet1/0
Set of tunnels with source Ethernet1/0, 1 member (includes iterators), on interface <OK>
Tunnel protocol/transport multi-GRE/IPv6
Key disabled, sequencing disabled
Checksumming of packets disabled
Tunnel TTL 255
Tunnel transport MTU 1456 bytes
Tunnel transmit bandwidth 8000 (kbps)
Tunnel receive bandwidth 8000 (kbps)
Last input never, output never, output hang never
      Step 2   show tunnel endpoints tunnel tunnel-interface

      This command displays tunnel interface endpoints and verifies if the tunnel is created correctly.



      Example: 
      Device# show tunnel endpoints tunnel 1
 
Tunnel 1 running in multi-GRE/IPv6 mode
Endpoint transport 1101:2::1 Refcount 3 Base 0x2B83A87F83D8 Create Time 00:22:05
overlay 1101:1::1 Refcount 2 Parent 0x2B83A87F83D8 Create Time 00:22:05
Tunnel Subblocks:
tunnel-nhrp-sb:
NHRP subblock has 1 entries
      Step 3   show ipv6 traffic

      This command displays statistics about IPv6 traffic on a tunnel.



      Example: 
      Device# show ipv6 traffic
 
IPv6 statistics:
        Rcvd:  46 total, 34 local destination
               0 source-routed, 0 truncated
               0 format errors, 0 hop count exceeded
               0 bad header, 0 unknown option, 0 bad source
               0 unknown protocol, 0 not a router
               0 fragments, 0 total reassembled
               0 reassembly timeouts, 0 reassembly failures
        Sent:  54 generated, 0 forwarded
               0 fragmented into 0 fragments, 0 failed
               8 encapsulation failed, 0 no route, 0 too big
               0 RPF drops, 0 RPF suppressed drops
        Mcast: 22 received, 21 sent

ICMP statistics:
        Rcvd: 37 input, 0 checksum errors, 0 too short
              0 unknown info type, 0 unknown error type
              unreach: 0 routing, 0 admin, 0 neighbor, 0 address, 0 port
                       0 sa policy, 0 reject route
              parameter: 0 error, 0 header, 0 option
              0 hopcount expired, 0 reassembly timeout,0 too big
              0 bad embedded ipv6
              10 echo request, 0 echo reply
              0 group query, 0 group report, 0 group reduce
              0 router solicit, 7 router advert, 0 redirects
              4 neighbor solicit, 6 neighbor advert
        Sent: 47 output, 0 rate-limited
              unreach: 0 routing, 0 admin, 0 neighbor, 0 address, 0 port
                       0 sa policy, 0 reject route
              parameter: 0 error, 0 header, 0 option
              0 hopcount expired, 0 reassembly timeout,0 too big
              0 echo request, 10 echo reply
              0 group query, 0 group report, 0 group reduce
              3 router solicit, 7 router advert, 0 redirects
              6 neighbor solicit, 6 neighbor advert

UDP statistics:
  Rcvd: 0 input, 0 checksum errors, 0 length errors
        0 no port, 0 dropped
  Sent: 0 output

TCP statistics:
  Rcvd: 0 input, 0 checksum errors
  Sent: 0 output, 0 retransmitted

      Configuration Example for mGRE Tunnel over IPv6

      Example for mGRE Tunnel over IPv6

      mGRE Tunnel over IPv6

      Configuring mGRE tunnel over IPv6 transport. 

      ! Configure the topology

R1(config)# ipv6 unicast-routing
R1(config)# ipv6 cef
R1(config)# interface Ethernet0/1
R1(config-if)# ipv6 address 2001:DB8:1111:1111::1/64
R1(config-if)# no shutdown
R1(config-if)# exit
R1(config)# ipv6 route ::/0 2001:DB8:1111:1111::2

! Configure the tunnel interface on hub

Hub(config)# ipv6 unicast-routing
Hub(config)# interface tunnel 1
Hub(config-if)# description DMVPN HUB
Hub(config-if)# ipv6 address 2001:DB8:1111:4444::1/64
Hub(config-if)# ipv6 nhrp map multicast dynamic
Hub(config-if)# ipv6 nhrp network-id 100
Hub(config-if)# ipv6 nhrp holdtime 100
Hub(config-if)# tunnel source Ethernet0/1
Hub(config-if)# tunnel mode gre multipoint ipv6

! Configure the physical interface on the hub

Hub(config)# ipv6 unicast-routing
Hub(config)# interface Ethernet0/0
Hub(config-if)# ipv6 address 2001:DB8:1111:2222::1/64
Hub(config-if)# no shutdown
Hub(config-if)# exit
Hub(config)# ipv6 route ::/0 2001:DB8:1111:2222::2


! Configure the tunnel interface on spoke 

Spoke1(config)# ipv6 unicast-routing
Spoke1(config)# interface tunnel 1
Spoke1(config-if)# description DMVPN Spoke 1
Spoke1(config-if)# ipv6 address 2001:DB8:1111:4444::2/64
Spoke1(config-if)# ipv6 nhrp map multicast dynamic
Spoke1(config-if)# ipv6 nhrp map 2001:DB8:1111:4444::1/64 2001:DB8:1111:3333::1
Spoke1(config-if)# ipv6 nhrp map multicast 2001:DB8:1111:3333::1
Spoke1(config-if)# ipv6 nhrp network-id 100
Spoke1(config-if)# ipv6 nhrp holdtime 100
Spoke1(config-if)# ipv6 nhrp nhs 2001:DB8:1111:4444::1
Spoke1(config-if)# tunnel source Ethernet0/0
Spoke1(config-if)# tunnel mode gre multipoint ipv6

! Configure the physical interface on the spoke

Spoke1(config)# interface Ethernet0/0
Spoke1(config-if)# ipv6 address 2001:DB8:1111:2222::2/64
Spoke1(config-if)# exit

! Configure the R2 device at the spoke 

R2(config)# interface Ethernet0/1
R2(config-if)# ipv6 address 2001:DB8:1111:3333::1/64
R2(config-if)# no shutdown
R2(config-if)# exit
R2(config)# ipv6 route 2001:DB8:1111:1111::/64 2001:DB8:1111:2222::1

      Additional References

      Related Documents

      Related Topic

      Document Title

      IPv6 addressing and connectivity

      IPv6 Configuration Guide

      Cisco IOS commands

      Cisco IOS Master Command List, All Releases

      IPv6 commands

      Cisco IOS IPv6 Command Reference

      Cisco IOS IPv6 features

      Cisco IOS IPv6 Feature Mapping

      Standards and RFCs

      Standard/RFC

      Title

      RFCs for IPv6

      IPv6 RFCs

      MIBs

      MIB

      MIBs Link

      To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL:

      http:/​/​www.cisco.com/​go/​mibs

      Technical Assistance

      Description

      Link

      The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password.

      http:/​/​www.cisco.com/​cisco/​web/​support/​index.html

      Feature Information for mGRE Tunnel Support over IPv6

      The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

      Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to . An account on Cisco.com is not required.
      Table 1 Feature Information for mGRE Tunnel Support over IPv6

      Feature Name

      Releases

      Feature Information

      mGRE Tunnel Support over IPv6

      15.2(1)T

      XE Release 3.8S

      mGRE tunnels are configured to enable service providers deploy IPv6 in their core infrastructure.