6rd configuration

[sachin30720041]

Hello,

I am trying to configure 6rd  between 2 CSRs.

I have created 2 loopbacks lo4 on both the CSRs.

And Lo4's prefix is the same as the general prefix of 6rd tunnels.

R2-----R3

R2#show tunnel 6rd tunnel 1

Interface Tunnel1:

Tunnel Source: 2.2.2.2

6RD: Operational, V6 Prefix: 2001:FACE::/32

V4 Prefix, Length: 8, Value: 2.0.0.0

V4 Suffix, Length: 0, Value: 0.0.0.0

General Prefix: 2001:FACE:202:200::/56

lo4 on R2.

interface Loopback4
ipv6 address 2001:FACE:202:200::1/128

R3#show tunnel 6rd tunnel 1

Interface Tunnel1:

Tunnel Source: 3.3.3.3

6RD: Operational, V6 Prefix: 2001:FACE::/32

V4 Prefix, Length: 8, Value: 3.0.0.0

V4 Suffix, Length: 0, Value: 0.0.0.0

General Prefix: 2001:FACE:303:300::/56

lo4 on R3.

interface Loopback4
ipv6 address 2001:FACE:303:300::1/128

There is a static route on both the routers pointing to the tunnel.

ipv6 route 2001:face::/32 tunnel1

But ping does not work between lo4 of r2 and lo4 of r3.

Below is the complete configuration on both routers. I am not sure why ping is not working.

CSR2

-----------

ipv6 unicast-routing

int gi1

ip address 100.10.20.2 255.255.255.0

no sh

ip ospf 1 area 0

int gi3

ip address 100.20.30.2 255.255.255.0

no sh

ip ospf 1 area 0

int lo0

ip address 2.2.2.2 255.255.255.255

ip ospf 1 area 0

int lo4

ipv6 address 2001:face:1000:200::2/128

int tunnel1

ipv6 address 2001:face::2/128

tunnel source lo0

tunnel mode ipv6ip 6rd

tunnel 6rd prefix 2001:face::/32

tunnel 6rd ipv4 prefix-len 8

ipv6 route 0::0/0 tunnel1 2001:face:1000:100::

ipv6 route 2001:face::/32 tunnel1

interface Loopback4

no ip address

ipv6 address 2001:FACE:202:200::1/128

end

CSR3

-------------

ipv6 unicast-routing

ipv6 route 2001:face::/32 tunnel1

int tunnel1

ipv6 address 2001:face::3/128

tunnel source lo0

tunnel mode ipv6ip 6rd

tunnel 6rd ipv4 prefix-len 8

tunnel 6rd prefix 2001:face::/32

ipv6 unicast-routing

int gi3

ip address 100.20.30.3 255.255.255.0

no sh

ip ospf 1 area 0

int gi2

ip address 100.10.30.3 255.255.255.0

no sh

ip ospf 1 area 0

int lo0

ip address 3.3.3.3 255.255.255.255

ip ospf 1 area 0

interface Loopback4

no ip address

ipv6 address 2001:FACE:303:300::1/128

end

ipv6 route 2001:face::/32 tunnel1

[balaji.bandi]

Do you have OSPF neighbourship ?

can you post the below output from both the devices :

show IP interface brief

show ospf neigh

check some sample config :

https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/interface/configuration/xe-16-9/ir-xe-16-9-book/ip6-6rd-tunls-xe.html#GUID-77366043-AFFE-42A5-9B6C-C37734A44E2C

[Harold Ritter · Accepted solution]

Hi @sachin30720041 ,

Since you configured the ipv4 prefix length to be 8, both the source and destination need to shared the first 8 bits. In your case, R2 has lo0 2.2.2.2 and R3 has a lo0 3.3.3.3, but since R2 sends packet using its local ipv4 prefix 2 with the suffix present in the ipv6 address (3.3.3) packets will be sent to 2.3.3.3, which will fail, as you don't have a proper 6rd BR for that destination address. 

You need to change the CSR3 lo0 to 2.3.3.3. 

Also remove the ipv6 address from the tunnel interface, which is not required and not part of the allocated 6rd space.

CSR2:

int tu1

no ipv6 address

ipv6 enable

CSR3:

int tu1

no ipv6 address

ipv6 enable

Regards,