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Subnet mask 16 bit 24 bit.

By brunner ·
I had a user (Windows Admin) who made a request to have our subnet mask on our NAT end from 16 bit to a 24 bit mask.
His chief concern was the windows machines performance, which he said was being impacted by all the Broadcast traffic.
We are a large network with Mulitple Gig Backbones and the LAN traffic has a lot of "head room"

My question is this a valid concern/issue?

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by BFilmFan In reply to Subnet mask 16 bit 24 bit ...

The answer truly depends on how the network traffic is segmented. Is it on a switch? Is there a large amount of broadcast traffic? What version of Windows is on the server?

My honest answer is that the server isn't being impacted.

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by CG IT In reply to Subnet mask 16 bit 24 bit ...

subnet maks doesn't affect performance because of broadcast traffic. Just filter ICMP traffic if you've got a problem.

The purpose of a subnet mask is to mask the network portion of the IP address so that only the host portion is read.

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by SamTheDon In reply to Subnet mask 16 bit 24 bit ...

just chk the patch cord,as it might be generating broadcast traffic,changing subnet from 16 to 24 bit does not affect traffic,only the performance does not impact the particular m/c only.

i dont this is a valid concern for an administrator

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by mshavrov In reply to Subnet mask 16 bit 24 bit ...

The amount of a broadcast traffic does not depend much on your subnet mask. But it depends havily on quantity of hosts in your subnet.

For example, if you have /16 mask for your network, and you have 1000 servers. If each server sends 1 broadcast packet per second, you have 1000 broadcasts per second. But if you have /24 mask, and you have 5 subnets with 200 servers each, then each subnet will have 200 broadcasts per second.

Even though private addresses are widely available, splitting your network to smaller subnets makes it more manageable. We have a problem with /16 mask when we need to do network security scanning. Just imagine scanning 16k hosts to find just a hundred servers...

Good luck,

Michael Shavrov
CCNP, CCDP, CCSP, MCSE W2K, MCSE+I, Security+, etc.
http://www.ciscoheadsetadapter.com

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by chaudharyjee In reply to Subnet mask 16 bit 24 bit ...

Subnet maks doesn't affect performance of your network..it depends on the number of hosts in your subnet!
The purpose of a subnet mask is to mask the network portion of the IP address so that only the host portion is read.

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