Private networks 172.15.0.0

[lasteeno]

I administer a private network for a company. Internal on my network, i have address in the 172.15.0.0 range. Technically, the private address space doesn't begin until 172.16.0.0.
Is 172.15.x.x allocated publically? Will I encounter problems if I leave this 172.15.x.x present on my LAN?

 

[bierhunter]

Yes, 172.15.x.x is publicly allocated, although doing a search, I haven't found yet who has it. If you keep this address range internally, you most likely won't notice anything, unless you try to communicate with whomever has an address in that range. Then your router will think that is your internal subnet and it won't send out the packet.

Years ago when I was with an ISP, we had a couple of customers with this exact same problem. One left to another ISP. Their old subnet was reassigned to a new customer. This new customer just happened to be a business associate of our old customer. Suddenly, the two businesses could no longer email or anything to each other.

Once we found out what the problem was, the old customer had to resubnet internally to fix it.

I would avoid the potential problems and resubnet to a private range now, so you won't have to do it in a crisis later on.

BierHunter
CNE, MCSE, CCNP

 

[bcastner]

Fix the subnet issue. It could be a problem down the road, and yes, you are not entitled to use the addressing you are now using.

RFC 1918 requests that organizations make use of the private Internet address space for hosts that require IP connectivity within their enterprise network, but do not require external connections to the global Internet. For this purpose, the IANA has reserved the following three address blocks for private internets:

10.0.0.0/8
127.0.0.0/8
172.16.0.0/12
192.168.0.0/16
IP's above 224.0.0.0 are used for both multicast and experimental purposes.

 

[chieftan999]

127 address range is reserved for loopback testing I thought???????

 

[bcastner]

chieftan999,

Yes it is, and reserved as a private IP range by the IANA.