6 to 4 tunneling

[Moshi]

IPv6

i had this error. what happen?

%Tunnel0: Error: 2001:DB9::/43 is overlapping with 2001:DB9::/64 on FastEthernet0/0

[Martin L · Accepted solution]

overlapping  means that 1 address falls into range of the another one. you cannot have that on a router. router should have all its interfaces in different networks.  like 10.10.0.1 /24 falls into 10.10.1.1 /16

here, 2001:DB9::/64 falls into range of 2001:DB9::/43.  not sure where the "border" is; where 43 bit ends; somewhere in 3rd nibble (1 hex is 4 bits) but I wouldn't do ipv6 without calculator.

Regards, ML
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[Deepak Kumar]

HI,

 2001:DB9::/43

2001:DB9::/64

check the both subnets.  It is clearly showing that the network portion of the complete subnet is matching. It shows overlapping. The router will not allow configuring overlapping subnetting in the same VRF.