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<article>

<title>RTACCT Utility
<author>Robert Olsson
<date>some_negative_number, 20 Dec 2001

<p>
Here is some code for monitoring the route cache. For systems handling high
network load, servers, routers, firewalls etc the route cache and its garbage
collection is crucial. Linux has a solid implementation.

<p>
The kernel patch (not required since linux-2.4.7) adds statistics counters
from route cache process into 
/proc/net/rt_cache_stat. A companion user mode program presents the statistics
in a vmstat or iostat manner. The ratio between cache hits and misses gives 
the flow length.

<p>
Hopefully it can help understanding performance and DoS and other related
issues.

<p> An URL where newer versions of this utility can be (probably) found
is ftp://robur.slu.se/pub/Linux/net-development/rt_cache_stat/


<p><bf/Description/

<p>The format of the command is:

<tscreen><verb>
       rtstat [ OPTIONS ]
</verb></tscreen>

<p> <tt/OPTIONS/ are:

<itemize>

<item><tt/-h/, <tt/-help/ - show help page and version of the utility.

<item><tt/-i INTERVAL/ - interval between snapshots, default value is
2 seconds.

<item><tt/-s NUMBER/ - whether to print header line. 0 inhibits header line,
1 prescribes to print it once and 2 (this is default setting) forces header
line each 20 lines. 

</itemize>

</article>
