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We are using class-C IP addresses in our network setup.

The first scope of IP addresses are in Since all the IPs are exhausted in this scope we created another scope of Class-C IP in the same Domain Controller. This scope has IP addresses in

The issue we are facing is, whenever a client with IP address in the scope, tries to copy a file to a client with IP address in scope the copy is dead slow.

For e.g., transfer rate of a 1 GB file between clients in same IP scope will be around 35 MBPS or more whereas copy of the same file between clients in different IP scope will be around 5 MBPS or sometimes even lesser (sometimes drops to 0).

What is happening here? Is there a solution to make copy faster. The type of work we do requires huge data transfer between clients and changing the IP scope to a class A scope may be a out of question since we are a little short on resources to do the transition.

Am I missing some setting or something on the Domain controller or the router which is causing the copy to go so slow.

This issue is not fixed to any specific kind of OS, it happens across all types of OS we have - Windows or Mac.

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migrated from Jul 3 '12 at 12:54

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Switch to a class A network so everyone knows how to find everyone else. 10.x.x.x. – bmargulies Jul 3 '12 at 12:26
Classful networking has been replaced by CIRD since 1993. This means no more 'Class A' etc etc, but /X. E.g. /8 for old class A networks. This also allows you to create a /23 with up to 512 IPs in a network rather then tie two /24 ('c')'s together. – Hennes Sep 10 '13 at 12:31

Without knowing your entire network topology, this is quite hard to answer.

My guess is that everything is going via a gateway and the traffic is being doubled up somewhere (e.g. going in and out of the gateways same lan port).

My advice would be to change the subnet mask - If you are only using and - simply change the subnet mask to and everything should work fine.

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Even stricter subnet mask is possible for those two classes: – Radoo Jul 3 '12 at 13:45

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