[CentOS] Performance of CentOS as a NAT gateway
Ross S. W. Walker
rwalker at medallion.com
Mon Sep 10 20:35:59 UTC 2007
Bart Schaefer wrote:
> On 9/9/07, Barry Brimer <lists at brimer.org> wrote:
> > Maybe it is time for some kernel networking tuning.
> After doing a bit of research:
> I ended up with this:
> net.core.rmem_default = 873800
> net.core.wmem_default = 655360
> net.core.rmem_max = 8738000
> net.core.wmem_max = 6553600
> net.ipv4.tcp_rmem = 8192 873800 8738000
> net.ipv4.tcp_wmem = 4096 655360 6553600
> net.ipv4.tcp_mem = 195584 873800 8738000
> (The first number in tcp_mem is the original default.)
> ifconfig eth0 txqueuelen 1000
> ifconfig eth1 txqueuelen 1000
> Unfortunately so far this doesn't seem to have made any difference.
> We've had a load peak going since early this morning and the traffic
> looks exactly like it did last week.
The only way your going to know for absolute sure where the bottleneck
exists is to do a wireshark/tcpdump trace simultaneously on both sides.
Then with that information you will know where the bottleneck is and
armed with that you can start exploring why there is a bottleneck
Off the top of my head, there could be a IP MTU mismatch somewhere and
with ICMP disabled this would cause a blackhole for some full packet
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