<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns="http://www.w3.org/TR/REC-html40"> <head> <meta http-equiv=Content-Type content="text/html; charset=us-ascii"> <meta name=Generator content="Microsoft Word 11 (filtered medium)">  <style>  </style> </head> <body lang=EN-US link=blue vlink=purple> <div class=Section1> In doing a quick with the 2.4.28 kernel, after flushing the cache with ip route flush cache, 5mins later we get the infamous “dst cache overflow” messages. Doing a route –Cn | wc results in the following on each time the messages started to appear:<o:p></o:p> <o:p> </o:p> 5mins<o:p></o:p> 4095 29609 315201<o:p></o:p> <o:p> </o:p> 5mins<o:p></o:p> 4093 29575 315043<o:p></o:p> <o:p> </o:p> Our /proc/sys/net/ipv4/route/max_size is set to 4096, so I guess that’s why we get the messages, but eventually the network connections stop and the firewall needs to be hard rebooted. So I’m not sure of the point in setting that, unless there is a memory leak somewhere… <o:p></o:p> <o:p> </o:p> <div> Thanks,<o:p></o:p> Michael Brown<o:p></o:p> </div> <div> <div class=MsoNormal align=center style='text-align:center'> <hr size=2 width="100%" align=center tabindex=-1> </div> </div> From: fedora-list-bounces@redhat.com [mailto:fedora-list-bounces@redhat.com] On Behalf Of Fedora Posted At: Wednesday, December 08, 2004 1:32 PM Posted To: Fedora Conversation: kernel: dst cache overflow Subject: kernel: dst cache overflow I have been searching all over the internet for a solution to the common “kernel: dst cache overflow” problem people have been having… Here’s my synopsis, I am running 14 Linux firewalls, 9 on Fedora core 2, 1 on Fedora core 1 and 3 on Red Hat 9. All of the firewalls have about 3-4 Copper Gig NICs, on Dell PowerEdge 700 with 512mb memory and a P4 2.8Ghz CPU. The firewalls have just above bare minimal pkgs installs, all installed from a kickstart file and all services (if any un-used) have been turn off and disable in the runlevels. These are only firewalls for internet and private traffic across T1’s and higher. All fedora core 2 firewalls have and running the latest kernel 2.6.9-1.6_FC2smp, but each kernel before that also had the errors, so there are no fixes in the kernel. All Red Hat firewalls are running 2.4.25 kernel and the 1 fedora core 1 is running 2.4.26, but none of them are experiencing this issue.<o:p></o:p> <o:p> </o:p> On the Fedora Core 2 firewalls, I get the below kernel messages after a certain amount of traffic, what that amount is, I do not know. <o:p></o:p> <o:p> </o:p> kernel: dst cache overflow<o:p></o:p> kernel: printk: 52 messages suppressed.<o:p></o:p> kernel: dst cache overflow<o:p></o:p> kernel: printk: 36 messages suppressed.<o:p></o:p> kernel: dst cache overflow <o:p></o:p> <o:p> </o:p> After so much traffic or time, the firewall becomes unresponsive on the network and I may or may not get this new message, and the system needs a hard reboot.<o:p></o:p> syslogd: sendto: No buffer space available<o:p></o:p> kernel: dst cache overflow<o:p></o:p> last message repeated 5 times<o:p></o:p> last message repeated 9 times<o:p></o:p> last message repeated 3 times<o:p></o:p> syslogd: sendto: No buffer space available<o:p></o:p> kernel: dst cache overflow<o:p></o:p> last message repeated 3 times<o:p></o:p> last message repeated 3 times<o:p></o:p> <o:p> </o:p> I have tried just resetting the network ( service network restart), I also tried just to stop the network for a few hours, I tried the recommendation of setting the route max_size in /proc/sys/net/ipv4/route/max_size (<a href="http://seclists.org/lists/vulnwatch/2003/Apr-Jun/0076.html">http://seclists.org/lists/vulnwatch/2003/Apr-Jun/0076.html</a>), none seemed to help. I am now trying a custom 2.4.28 kernel on one of the firewalls to see if that may help. <o:p></o:p> <o:p> </o:p> Has anyone run into this and fixed it? It seems to be only with Fedora Core 2, I am curious if Fedora 3 would make a difference, but I am not ready to leap into that bird nest just yet.<o:p></o:p> <o:p> </o:p> <o:p> </o:p> Thanks,<o:p></o:p> Michael Brown<o:p></o:p> <o:p> </o:p> </div> </body> </html>