01-16-2012 03:19 PM - edited 03-01-2019 05:32 PM
Hi everybody.
please consider the following address- overlapping- scenario:
R2(config)#int loopback 2
R2(config-if)#ipv6 address 2002:a09:901:1::1/64
R2(config-if)#int tunnel 1
R2(config-if)#ipv6 address 2002:a09:901::/128
I don't get any error even though we have overlapping address. For example, the range of valid ipv6 address on subnet 2002:a09:901::/64 is
2002:a09:901:: ---- 2002:a09:901:FFFF:FFFF:FFFF:FFFF:FFFF
The address 2002:a09:901:: configured on tunnel interface falls with in the range described above but yet we don't get any error message.
If I perform the similar action on ipv4 enabled interface, I will get error.
R2(config)#int loopback 4
R2(config-if)#ip address 12.12.12.12 255.255.0.0
R2(config-if)#int loopback 13
R2(config-if)#ip address 12.12.12.12 255.255.255.0
% 12.12.12.0 overlaps with Loopback4
In above case we get error because address 12.12.12.12/24 falls in the range of subnet 12.12.0.0/16. However in case of ipv6, the address 2002:a09:901::/128 on tunnel1 falls with in range of prefix 2002:a09:901::/64,but yet we don't get any error message.
Any input will be greatly appreciated.
Solved! Go to Solution.
01-17-2012 05:49 AM
If the example you provided is as you typed it in the IOS CLI then these are not overlapping IPv6 ranges
The range on loopback2 in it's expanded format is:
2002:0a09:0901:0001::1/64
The range on tunnel 1 is
2002:0a09:0901:0000::/128
These are different /64s (/64 boundary is after the 4th Hextet, not after the embedded IPv4 address which is a /48)
I hope this clarifies the issue.
01-18-2012 07:10 AM
Hopefully this will help:
int loopback2
2002:0a09:0901:0001::1/64
Range will be 2002:0a09:0901:1:0:0:0:0------2002:0a09:0901: 1:ffff:fffff:ffff:ffff
Correct
int tunnel
2002:0a09:0901:0000::/128
This address with any mask from /64 - /128 will _not_ overlap with the above subnet of loopback 2
If the mask is any smaller then /64 (
My point about the /48 vs /64 was just a point of clarification to ensure you were not assuming that the /64 bit boundary wasn't somewhere where it wasn't. For all intents and purposes ignore this if it is confusing and just focus on the above.
I hope this helps
01-17-2012 05:49 AM
If the example you provided is as you typed it in the IOS CLI then these are not overlapping IPv6 ranges
The range on loopback2 in it's expanded format is:
2002:0a09:0901:0001::1/64
The range on tunnel 1 is
2002:0a09:0901:0000::/128
These are different /64s (/64 boundary is after the 4th Hextet, not after the embedded IPv4 address which is a /48)
I hope this clarifies the issue.
01-17-2012 05:39 PM
HI stmillet.
I am still at loss.
I am going to break it down for better understanding for myself
int loopback2
2002:0a09:0901:0001::1/64
Range will be 2002:0a09:0901:1:0:0:0:0------2002:0a09:0901: 1:ffff:fffff:ffff:ffff
is that the correct range?
int tunnel
2002:0a09:0901:0000::/128
First , I need to clarify what prefix length are you referring to is 48/ or 128?
Let say it is 48 .i.e 2002:0a09:0901::/48
then range will be: 2002:0a09:0901:0:0:0:0:0----- 2002:0a09:0901:ffff:ffff:ffff:ffff:ffff
the adress assigend to loopback2 i.e 2002:0a09:0901:1::1 falls in the above range. Is that correct ?
thanks and I appreciate your help.
01-18-2012 07:10 AM
Hopefully this will help:
int loopback2
2002:0a09:0901:0001::1/64
Range will be 2002:0a09:0901:1:0:0:0:0------2002:0a09:0901: 1:ffff:fffff:ffff:ffff
Correct
int tunnel
2002:0a09:0901:0000::/128
This address with any mask from /64 - /128 will _not_ overlap with the above subnet of loopback 2
If the mask is any smaller then /64 (
My point about the /48 vs /64 was just a point of clarification to ensure you were not assuming that the /64 bit boundary wasn't somewhere where it wasn't. For all intents and purposes ignore this if it is confusing and just focus on the above.
I hope this helps
01-22-2012 09:55 AM
Thanks Stmillet. I apologies for the late reply.
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