Ok everyone. I want to apologize for this post. The culprit was a poorly configured Cisco 2950 switch (2 of them to be precise). On VLAN creation, STP (spanning tree) is enabled by default. Disabling this feature completely eliminated all the funky latency issues I've been experiencing. Doh! -Ken -----Original Message----- From: Ken Price [mailto:kprice@agentware.net] Sent: Friday, October 25, 2002 2:27 PM To: 'Stef Coene'; lartc@mailman.ds9a.nl Subject: RE: MTU problem with simple router? Yes. Nothing out of the ordinary. I'm seeing packets being sent at 1460 and returned at 1448 - both under my interface's MTU of 1500. I even tried with MTU sizes down to 500 at the firewall. No luck. The TCPDUMP actually looks just like our development firewall's TCPDUMP in the office - and development works fine. So I'm lost. The routers in question are Dell 350's ... PIII-850s with 256Mb RAM with Intel Pro100 NICS, plus one has a 4-port Znyx card (tulip drivers). Page data (just the HTML text) is returned within 1-2 seconds in development or on an outer production router, 8-10 seconds within production. That's a considerable difference. Leaving firewalling out of it, if you were to setup a Linux router to simply bridge two subnets, after assigning the correct IPs to the interfaces, setting the default gateway to the enterprise router of the ISP, and # echo 1 > /proc/sys/net/ipv4/ip_forward what needs to be done? Ken -----Original Message----- From: Stef Coene [mailto:stef.coene@docum.org] Sent: Friday, October 25, 2002 1:22 PM To: Ken Price; lartc@mailman.ds9a.nl Subject: Re: MTU problem with simple router? On Friday 25 October 2002 18:53, Ken Price wrote: > All of our public IPs are reverse mapped. The initial connection to the > site is fast. The delay happens when data starts comming back. A way to > visualize this problem is using a browser. You hit "Go" and the target > site immediately returns text, but like a low-bandwidth or overloaded site, > graphics trickle back. This problem is not limited to a single site ... > it's all of them. And isn't limited to a single router, I have two > different production evironments setup with different loadbalancer/firewall > combos. What they both have in common is the RedHat router doing simple > forwarding. One in each environments. Stange. Have you tried to dump the packets with tcpdump so you can analyse what happens ? Stef -- stef.coene@docum.org "Using Linux as bandwidth manager" http://www.docum.org/ #lartc @ irc.oftc.net _______________________________________________ LARTC mailing list / LARTC@mailman.ds9a.nl http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/ _______________________________________________ LARTC mailing list / LARTC@mailman.ds9a.nl http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/
