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 <job@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