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Company acquired Subnet issues

prakashcsco
Beginner
Beginner

HI   if   A company with 10.0.0.0/8 subnet acquired a company B which also having 10.0.0.0/8 range IP. how we can we resolve this scenario as both are using same subnet.

 

 

2 Accepted Solutions

Accepted Solutions

Jon Marshall
VIP Community Legend VIP Community Legend
VIP Community Legend

 

That is a large range so there may not be any overlapping but if there is basically you need to look to readdress the subnets that do. 

 

As a temporary measure you may be able to use NAT to communicate between subnets using the same range but that would only be a short term solution, you really need to readdress. 

 

Jon

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Karsten Iwen
VIP Mentor VIP Mentor
VIP Mentor

Jon already mentioned the best option (readdress the network) and the worst option (NAT). There is a third that at least should be evaluated: Adding IPv6 on top of both networks for the systems that need to communicate with each other.

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6 Replies 6

prakashcsco
Beginner
Beginner

Additing some details 

 

Company have DMVPN  and using EIGRP for routing. 

prakashcsco
Beginner
Beginner

Adding some details 

 

Company A have DMVPN  and using EIGRP for routing. 

Jon Marshall
VIP Community Legend VIP Community Legend
VIP Community Legend

 

That is a large range so there may not be any overlapping but if there is basically you need to look to readdress the subnets that do. 

 

As a temporary measure you may be able to use NAT to communicate between subnets using the same range but that would only be a short term solution, you really need to readdress. 

 

Jon

Karsten Iwen
VIP Mentor VIP Mentor
VIP Mentor

Jon already mentioned the best option (readdress the network) and the worst option (NAT). There is a third that at least should be evaluated: Adding IPv6 on top of both networks for the systems that need to communicate with each other.

Joseph W. Doherty
Hall of Fame Master Hall of Fame Master
Hall of Fame Master

Just to add to what @Jon Marshall and @Karsten Iwen have noted, the NAT they refer to, I believe, is known as "double NAT".

Another issue you can easily run into, especially in the case of using two /8s, what address block do you map to for the other side to "see"?

Having been in this situation, i.e. merging two companies both using 10.0.0.0/8, you may end up NATting only some address blocks that really, really need to be accessed from the other side.  You then work, to try to partition 10.0.0.0/8 such that it can be "shared", without overlap, by the two companies.

BTW, in the (rather large) company where I encountered this situation, the new to be added company only used part of 10.0.0.0/8, as most companies would, however, our company actually used all of 10.0.0.0/8 (and 172.16.0.0/12 and 192.168.0.0/16).  (We were early adopters of IPv6 due to depletion of all IPv4 private address space.)

Leo Laohoo
VIP Community Legend VIP Community Legend
VIP Community Legend

@prakashcsco wrote:

A company with 10.0.0.0/8 subnet acquired a company B which also having 10.0.0.0/8 range IP.


That's a trick question.  10.0.0.0/8 is a private IP address.  No single individual or company "owns" this subnet.  

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