[CentOS] OT: looking for network performance comparison chart

[Simon Billis]

Hi Rudi,

> Does anyone have, or know of a comparison chart of the different
> network adapters, i.e. 1GB  / 10GB, Infiniband, etc. And if possible
> with a few top brand NIC's and switches listed as well.
> 
> I would like to see, for example, what the max throughput is of a 1GB
> NIC (and this could probably differ from PCI to PCIE-x1 to PCIE-x4),
> and 10GBE. Different switches would probably also have different
> ratings, but could a layer 2 switch & layer3 switch deliver the same
> performance for example?
> 
> Basically I need to know what upload / download speeds I should be
> getting from the different networks, set aside other options like CPU
> / RAM / disc IO / etc.

If you exclude the host capability to deliver data to the interface and also
the ability of the host to assemble and disassemble packets, then the speeds
will be dependent on the switches capability to handle the packet size and
numbers of packets arriving at an interface in a specific time period. You
should expect wirespeeds (minus the overhead of the Ethernet frame and the
IP frame) for most switches with usual packet sizes (below 1500 bytes) i.e.
the usual (if there is such a thing) packet size, provided that you're not
flooding the interfaces with very small packets and your switch is set to
store and forward. If your switch is able to cut and forward which is a must
for jumbo frames to be handled quickly, then you can also expect close to
wirespeeds for any frame size. Cut and forward switches are expensive but
are a must for storage networks if you're interested in low latency
switching.

Layer 3 switching is basically routing done on a switch and therefore
increases the latency slightly to a lot as the switch has to decode the
layer 3 information and make a decision based on that as opposed to the
outer layer 2 information.

Due to the many factors affecting network speeds, most switch manufacturers
specify the switch capability/capacity in backplane bandwidth, maximum
packet numbers switched per second and memory available for store and
forward. As soon as one of these limits is breached then the performance
will take a hit and this hit can be a big one.

I'm sorry that I can't be more helpful and provide you with what you're
after, but I hope that this has answered some questions for you.

Rgds

Simon.