I'm in the process of planning some segmentation for our network to better isolate systems, but ran into some specs that have introduced some new questions I didn't know to ask. We have some el-cheapo SG-300 cisco switches that can do rudimentary layer 3 switching, but apparently they have some tight limits that might be a problem. From this link I gleaned this:
The SX300 switch, in a layer 3 mode, it will hardware switch up to 100 IP addresses. Once above the 100 IP addresses, it gets in to software switching additional requests. The routing module in the switch can report SFFT over flow conditions once that treshhold is reached.
The MAC table can support up to 16000 MAC addresses. The IP table if I remember right should be maximum around 510.
However, this switch is designed for only 100 users. Anything above this can be beyond the capability of the switch.
I have realised now I have no idea how to "size" a layer 3 switch, or how to configure my topology to work around these limits. I was looking at ubiquiti's EdgeSwitch products and it appears in their admin guide on page 20:
The ARP cache can support 1,024 entries...
My intuition here says ARP cache >= # Hosts being routed is needed but I am not sure if that is correct, or even what effects a full cache would have on further clients. I assume it would mean constantly re-arping "who has x.x.x.x" if the switch was dealing with traffic constantly from more hosts than it has entries. Any guidance is appreciated.
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