[CentOS] Performance of CentOS as a NAT gateway

Bart Schaefer barton.schaefer at gmail.com
Sun Sep 9 18:37:46 UTC 2007

On 9/8/07, Ross S. W. Walker <rwalker at medallion.com> wrote:

> Has the Internet interface reached it's max capacity?


> Or are you saying that LAN-to-LAN traffic maxs out at 10Mbps, it is
> a little vague.

LAN-to-gateway traffic (e.g., a test FTP of a large file from the
gateway to a machine on one of the LANs) begins to degrade as the
LAN-to-internet traffic increases.  That's not surprising, but it
degrades disproportionately, i.e. when the FTP begins to show
intermittent stalls, the total traffic visible at the router on the
internet side of the gateway is only in the just-over-10Mb/s range.

Once we get to this point, no matter how many more LAN-to-internet
connections become active, the router on the internet side never sees
much over 10Mb/s of traffic.  We're not losing data or having an
unusual number of connection timeouts; each connection just slows
down.  We figured on some slowdown for NAT, but not 80%+.

LAN-to-LAN traffic that doesn't involve the gateway behaves more like
we'd expect, but I'm not sure that eliminates the switch as the

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