maximum throughput on network card

[William Pribble]

Hello,

What is the realistic maximum throughput on a pci gigabit network card and a pci 100mb network card? Any suggestions on the best way to monitor capacity and performance on the network cards?

Thanks

[John Bolene]

It depends on if you are running them thru a switched network or a hubbed network.

Switching gives each connection full bandwidth from the switch to the machine and the switch normally has a higher bandwidth connection out to the backbone. The hubbed connection is standard Ethernet and goes thru a collision detection algorithm. With several machines all wanting to talk at the same time, the switched will give better thruput.

Our tests show that hubbed gives about 60% utilization of the bandwidth before getting too many collisions resulting in retransmissions. The switched hums up to around 80% of bandwidth.

It all depends on how everything is connected and if you can segment network traffic by the use of routers to keep the maximum data flowing.

Hopefully this helps.

[Jim Turner]

Elaine,

There are a myriad of factors beyond the network. Take the example of two gigabit hosts connected back-to-back with a cross-over cable. This effectively removes all network variables.

You are still constrained by how fast you can actually get the data to the xcvr on the NIC. How fast is each machine's CPU, memory, disks, backplane, and bus adapter(s)? What processes do you have running that will contend for i/o or CPU thus impacting your network throughput?

What I'm trying to say here is that the only thing going gigabit ethernet (or even 100BT FD for that matter) will do for sure is remove the "network" as a limiting factor. The weakest link will now be something else. I have yet to see (and I have 62 HP-UX boxes) any instance of a box saturating a 100BT or GB link. Will it run faster? You bet. I've got GB ethernet b2b via xcable that shoots data through there like sh*t through a tin horn. Will it run right up at 100Mb or 1000Mb? Probably not.

I'd try some "real-life" tests. Try some different protocols (ftp, rcp, remsh), too. This is one case where your mileage will *definitely* vary.

Cheers,
Jim

[Jeff Carlin]

I found link to a document from Cupertino performance labs that I made a spreadsheet off of to calculate the maximum packet rate for a card based on the average packet size for that server. Use the lanadmin command to fetch the values.

Hope this helps... years later...

[William Wong_2]

There are lots of different factors that can affect the maximum throughput that you can achieve on a gigabit network card and a 100meg network card. You can measure the throughput using netperf. You can pickup a copy of netperf from the website: www.netperf.org. On the site there is also a database of submitted netperf benchmark numbers for different system configurations as well as network card configurations that you can peruse to get a feel for what the maximum throughput you can expect should be about. As for the measuring capacity and performance it is probably best done at the router port or switch port. And there's a variety of commercial tools available that will such as Lanalyzer or SolarWinds Standard Edition Toolset.

[Tim D Fulford]

1 - It, as always depends. Networking wat with what ... The best way to find out is to use netperf (www.netperf.org) or go to the HP-UX porting centre (I do not know the URL, sorry)

2 - Generally a a full duplex card can achieve 85-95% of advertised maximum, half duplex 65-75%.

3 - I use a database & bandwidth (kB/s) is not the problem it is throughput (pkt/s). Throughput is, geneerally, CPU related (as opposed to network card)

4 - As always MeasureWare C.03.70 (or above) will monitor BOTH bandwidth and throughput through each network interface. If you dont have MeasureWare then script something with lanadmin (there is a thread with this on I'll attache latter).

Regards

Tim

[Tim D Fulford]

here is the perl script.. kbit+pktRate.pl

[Steven E. Protter]

Interesting answers.

Theoretically its math.

100 Megabits per second, 8 bits to a byte.

In reality its really hard to push these cards to the limit unless you are running a public anonymous FTP server and have constant traffic, lots of machines.

I'm running a web hosting business on a Linux server with 384 Kbps of band width and rarely max that connection out, even with hundreds of people browsing the web sites.

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