Question : How much broadcast traffic is too much?

I have a small LAN with about 265 ips being used. These are all on the same subnet. While my users are not complaining, I am still concerned about the possibility that I have too many hosts on the same subnet thus potential problems such as too much broadcast traffic.

Is there a general rule how many hosts should be on a subnet or any type of calculator for determining how much broadcast traffic is too much?

While I would like to segregate my hosts, all these hosts need to access the same server due to them all using the same client server app. I have thought about implementing multiple VLANs and configuring servers so that their interfaces are able to handle traffic from multiple vlans. However, I am not certain that this is necessary.

Thank You.

Answer : How much broadcast traffic is too much?

microsoft and cisco seem to suggest about 250,

although some books state up to 500.

much of the problem was CPU usage would get hammered after about 200 PC but now it is all ofloaded this is less of a problem.

This question is really only like how long is a piece of string.

if you had 2000 pcs on the network but they did very little network talking. then you may be fine, on the other hand100 busy PC's may start to casue problems if there is a lot of broadcast traffic.

I was given a rule of thumb that if your broadcast traffic by packet numbers is greater than 5% then you really should consider splitting the network or doing some thing about it. However this again depends how busy your network is. I would say anything above 30 or 40 broadcast packets a second hitting an interface is also a sure sign its time to do something about it. rember every broadcast packet that hits a server nic is potentially reducing the pro-formance.

so thats

greater than 5% by packet number
more than 30 packets a second hitting the NIC (espicaly in the case of server NICS)
or more than 250 devices on a segment

I would say there the levels that you really want to start thinking about it, espicaly if you meet more than on of thoses.