Auto Negotiate versus Fixed Speeds on 10G SFP+ Modules

[ir8trader]

I was looking at the Qotom Q20332G9-S10 unit as outlined on one of the Youtube videos here as an option for a Performance Testing System. I need a 10G, preferably SFP+ interface on a mini-Server running iPerf3 or actually any other tools that allow me to send packets through a network link to validate speeds. Before I purchase a system or 2, I need to know if I can disable Auto-negotiate and hard code specific speeds on the 10G SFP+ Interface. I'll need at least 1G, 2.5G and 10G. Can I do that with the Qotom Q20332G9-S10 system and the installed NIC ?

Also, if anyone has any suggestions on performance software that can saturate a 10G Link and any other HW platforms like theQotom Q20332G9-S10 that are easily transportable, reasonably low cost, I'd be happy to listen to suggestions.

Thanks

 

[sko]

Usually this depends on the driver and has to be set there. To see the supported media types and options you can use ifconfig -m or ifconfig <iface> media and then use ifconfig <interface> media <mediatype> [mediaopts <mediaopts>] to set a fixed media type/option, hence disabling the autoselect.

That being said, SFP+ by default only supports 10Gbit and 1Gbit via SFP backwards compatibility. There are however some (usually copper) transceivers available that negotiate at other speeds while faking a 10Gbit link to the NIC.


iperf3 is single-threaded and hence CPU-restricted, so depending on system load you might see fluctuations in your measurements.
Also "validate speeds" isn't particulary specific... usually single-stream bandwidth (as measured by iperf3) doesn't really matter, because any halfway decent gear is able to reach/sustain line-speeds. So those metrics aren't of any use except for some colorful graphs for managers.
Much more important are things like PPS, forwarding rate etc - those heavily depend on your actual use-case and application(s). So you should first know (and probably tell us) with *what* you want to saturate the links - because this is mostly dictated by other factors than what the NICs can handle...

 

[ir8trader]

Thanks for the reply. At least for now, actual PPS using various Packet Sizes isn't as important as simply driving BW across a specific type of Network to Network link. I'm trying to validate several SFP based HW devices that support a variety of transport protocols and media types such as G.hn over Coax or Cat 5,6,7 and of course simple Fiber to Fiber connections. In almost all cases I'm looking to emulate the typical home traffic patterns to the Internet which has a mix of packet sizes but tends to lean toward ~1500 byte packets.

As far as SFP+ only supporting 10 and 1, yes, but there are NICs that support "Multi-Gig" and where I get confused is whether or not the drivers or OS supports the various speeds along with Auto. I'm assuming so, but I've assumed before.

It would also be nice to be able to transmit/generate packets without the need to involve a receiver, in other words, simply send a stream of packets to a MAC or IP so that I can validate the Router to Router Link speeds without having to worry about configuring a target server like IPerf3 does.

As to Iperf3 being single threaded, correct me if I'm wrong, but the -P option should allow me to use multiple parallel processes, but now I'm limited to Cores ?? Which if so is one reason why I am leaning toward the Qotom Q20332G9-S10 because of it's 8 cores.

Thanks.

 

[sko]

typical home traffic patterns to the Internet

I.e. only a fraction of the advertised/paid bandwidth is used and even this only in a handful of small bursts over the day?
99% of home users are completely clueless as to what their actual bandwitdth requirements are and wouldn't notice if their expensive Gbit line caps at <100Mbit thanks to massive ovesubscription and shitty uplinks in the ISP network...

It would also be nice to be able to transmit/generate packets without the need to involve a receiver, in other words, simply send a stream of packets to a MAC or IP so that I can validate the Router to Router Link speeds without having to worry about configuring a target server like IPerf3 does.

and what's the purpose of that, if you don't check what's coming through at a receiver/server side? sure, you could simply spit out UDP traffic to a broadcast address, but this has nothing to do with measuring the bandwidth of a link - you need to *measure* something for that...

As to Iperf3 being single threaded, correct me if I'm wrong, but the -P option should allow me to use multiple parallel processes,

read the manpage, it says streams. Yes, this somewhat conceals the underlying problem and usually you should be able to saturate 10GBit with any halfway recent hardware anyways (if you're not using some very-low-end systems/CPU...). But you should still keep this in mind if you have other loads running on that system and see fluctuations in your measurements.


Wild guess: the Quotom Q2033 devices can easily handle what you want to do (if you actually find out what you want to measure), and even the smaller CPU should easily suffice.
But for anything else than 1Gbit and 10Gbit you still have to use special transceivers and those can't be configured, only reflashed. So you will have to buy a pair of transceivers for the linespeed you want to enforce. Those are only available for standard ancient copper ethernet. For anything else (like G.hn you mentioned) you'd need media converters anyways - which usually have a fixed rate uplink port anyways. Same goes for the various SFP(+) modules for media other than standard ethernet over copper or fiber - they have fixed link rates which often are different from the port speed. (even SFP usually is rated at 1.19-1.25GBit physical link speed while the port is only 1Gbit)

 

[ir8trader]

I.e. only a fraction of the advertised/paid bandwidth is used and even this only in a handful of small bursts over the day?
99% of home users are completely clueless as to what their actual bandwitdth requirements are and wouldn't notice if their expensive Gbit line caps at <100Mbit thanks to massive ovesubscription and shitty uplinks in the ISP network...

You're preaching to the choir here.. but if you want to sell a networking device to an operator, you have to show it's performance capabilities. Unfortunately, what is advertised and sold versus what is used is wildly different, but people are sheep, it is what it is.


and what's the purpose of that, if you don't check what's coming through at a receiver/server side? sure, you could simply spit out UDP traffic to a broadcast address, but this has nothing to do with measuring the bandwidth of a link - you need to *measure* something for that...

I was going to measure it at the switch. Inna 2 switch environment, I can measure on both ends.


read the manpage, it says streams. Yes, this somewhat conceals the underlying problem and usually you should be able to saturate 10GBit with any halfway recent hardware anyways (if you're not using some very-low-end systems/CPU...). But you should still keep this in mind if you have other loads running on that system and see fluctuations in your measurements.

THis is a dedicated system for testing, no issue with other loads.


Wild guess: the Quotom Q2033 devices can easily handle what you want to do (if you actually find out what you want to measure), and even the smaller CPU should easily suffice.
But for anything else than 1Gbit and 10Gbit you still have to use special transceivers and those can't be configured, only reflashed. So you will have to buy a pair of transceivers for the linespeed you want to enforce. Those are only available for standard ancient copper ethernet. For anything else (like G.hn you mentioned) you'd need media converters anyways - which usually have a fixed rate uplink port anyways. Same goes for the various SFP(+) modules for media other than standard ethernet over copper or fiber - they have fixed link rates which often are different from the port speed. (even SFP usually is rated at 1.19-1.25GBit physical link speed while the port is only 1Gbit)

Thanks for the opinion on the Quotom., For fiber transceiver's I'm not really concerned as I would only use those to pass sufficient load data to the remote switch, they don't have to be 2.5 or 5, 1 or 10 is fine. For the actual Copper SFP modules, I don't need media converters, the devices are SFP based, conversion is done on an SOC on the SFP module, but as you say, there are some quirks where Auto-Negotiate may not work, in which case I have to disable it and set the speed.