
                                RTACCT Utility

Robert Olsson

   some_negative_number, 20 Dec 2001

   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.

   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.

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

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

   Description

   The format of the command is:

       rtstat [ OPTIONS ]

   OPTIONS are:

     * -h, -help - show help page and version of the utility.
     * -i INTERVAL - interval between snapshots, default value is 2
       seconds.
     * -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.
