Job, Fun! More generally, BGP has the same computing power as a Turing Machine:
Marco Chiesa, Luca Cittadini, Guiseppe Di Battista, Laurent Vanbever, and Stefano Vissicchio Using routers to build logic circuits: How powerful is BGP? (ICNP'13) http://vanbever.eu/pdfs/vanbever_turing_icnp_2013.pdf -- Jen On Apr 1, 2014, at 11:11 AM, Job Snijders <j...@instituut.net> wrote: > Hi all, > > Do you often find yourself in need of a simple calculator, and all you have > available to you is a Brocade or Cisco IOS router? No longer will you > experience the horror and dread of mental arithmetics. The route-map > calculator > is here! > > Brocade : http://instituut.net/~job/calculator-route-map.brocade.txt > Cisco IOS : http://instituut.net/~job/calculator-route-map.ioscisco.txt > (file size ~ 12 megabyte) > > In general I don't find route-maps useful to accomplish, well, anything. > However, this is a striking example of re-usable configuration that has > a measurable impact on daily operations! > > Calculations can be performed with integers between 1 and 256. The > answer will be presented as a rounded positive integer. In case the > calculation would result in a negative integer, larger than 2^16 > (65536), an helpful error message is generated: 65000:7777. For > divisions and substractions the order of the BGP communities is > relevant, one must always place the operator first! > > arithmetic operators: > > 'add' operator community: 65000:1 > 'multiply' operator community: 65000:2 > 'substract' operator community: 65000:3 > 'divide' operator community: 65000:4 > > example output: > > telnet@input-router#show ip bgp routes detail 10.1.1.1 | i COMMUNITIES > COMMUNITIES: 65000:2 0:63 0:113 ! calculate 63 * 113 > telnet@input-router# > > telnet@calculator#show ip bgp routes detail 10.1.1.1 | i COMMUNITIES > COMMUNITIES: 0:7119 ! result: 7119 > telnet@calculator# > > Super convenient right?! > > WARNING: due to IOS/Ironware architecture this route-map consumes quite > some memory. Always test in a lab before deploying in production! > > Kind regards, > > Job >
