<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <meta content="text/html;charset=ISO-8859-1" http-equiv="Content-Type"> </head> <body bgcolor="#ffffff" text="#000000"> Dan Young wrote: <blockquote cite="mid459D32FA.3080304@mesd.k12.or.us" type="cite"> <pre wrap="">Carl Keil wrote: </pre> <blockquote type="cite"> <pre wrap="">Can anyone suggest a way to test my LAN speeds that I'm using for K12LTSP? Screen redraws are jerky and slow on some of my clients. I've always suspected my network cabling wasn't quite right, but I don't know how to test it. </pre> </blockquote> <pre wrap=""> You can check for errors and find out what speed your NICs are negotiating with ifconfig and ethtool. Substitute your ethernet interfaces for eth0 (i.e. it may be eth1, etc.) "ifconfig eth0 | grep errors" Any number of errors is not good, especially if that number rises much over time. "ethtool eth0" Look at speed and duplex. Throughput can be monitored with iptraf (install w/ yum). The detailed interface statistics can tell you incoming/outgoing kbps. If your switches are "managed", you might want to use their command-line or web interfaces to look for CRC errors or similar. With these kind of problems, it pays to be methodical and check every device/port between the server and the client. </pre> </blockquote> And to actually generate some test traffic, I take a reasonably powerful box (dual-Athlon desktop, Core Duo laptop, or whatever) and use the following command: [microman@takhisis ~]$ su root Password: [root@takhisis microman]# ping -f -s 15000 w.x.y.z where w.x.y.z is some other pretty beefy box on the other side of the link. What you're doing here is called a "flood" ping, and you're specifying a packet size of 15,000 bytes/packet. I will do this until I fill up the link. I've actually pegged an OC-12c with multiple such ping sessions. I would have, say, four of these from Box A pinging Box B, and I'd have another four or so from Box B going to Box A. So, you should have no trouble filling up a 100Mbps client link. Here's another way: fire up full-screen TuxType or TuxMath sessions on all of your clients, simultaneously. This *WILL* generate a boatload of traffic. All you need are 15 simultaneous sessions of this to peg the server's Gig-E link (one of them will use 73Mb/sec). Then, as Dan mentions above, check out the port statistics on your switch, assuming that it's a managed switch (e. g. BayStack 450T, Cisco Catalyst, or Amer.com SR48G2i). If you're not using a managed switch, it actually would be a wise investment; 24-port BayStack 450T's with a fiber Gig-E interface can be had on eBay for about $200. They work really well. --TP </body> </html>