Linux BRIDGE-STP-HOWTO: About The Linux Modular Bridge And STP
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# C. FAQ

Here you will find some of the frequently asked questions connected to bridging.

## FAQ

1. Hardware
  What hardware do I need to run a bridge with 2-`n` NICs.
  Can you please recommend some tools to measure a 2-port linux bridge throughput.
2. Software
  I'm running with kernel x.x.x. Is a patch out there, to give me chance to use this stuff?

### 1. Hardware

What hardware do I need to run a bridge with 2-`n` NICs.

I think a fat 486 or a modest Pentium should be able to keep up with 2x100Mbit pretty well, but I have never tested this. I don't think RAM will matter much (8 or 16MB and all should be fine). CPU will not matter a whole lot either (486/Pentium and all should be fine). I think the primary contributor is the type of bus (ISA, PCI) and the type of network cards (some network cards require less "work" than others). Big switches usually have immensely fat internal buses (3 or 4 gigabits is not uncommon). Standard PCI, for example, can't keep up with a gigabit ethernet cards.

Can you please recommend some tools to measure a 2-port linux bridge throughput.

Well, first question is: does it have 100mbit interfaces? If it hasn't (10mbit only), it shouldn't have problems with keeping up, almost regardless of the processor speed. If it does have 100mbit interfaces and you're not sure it will keep up, you can run a flood ping with big packets across it (ping -f -s 1450 `ipaddress`) and see whether it keeps up.

### 2. Software

I'm running with kernel x.x.x. Is a patch out there, to give me chance to use this stuff?

There are patches for and 2.2.14, 2.2.15. Since 2.3.47 it's in the mainstream kernel, so you don't need to patch. If you're talking about others, you will have to upgrade, if you need to bridge.

> Note: I've heared unconfirmed roumors about the 2.2.15 patches working without any change also with the 2.2.16 kernel. Anyone mind telling me about it?

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