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 : calculator-route-map.brocade.txt
Cisco IOS : 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 at input-router#show ip bgp routes detail 10.1.1.1 | i COMMUNITIES
COMMUNITIES: 65000:2 0:63 0:113 ! calculate 63 * 113
telnet at input-router#
telnet at calculator#show ip bgp routes detail 10.1.1.1 | i COMMUNITIES
COMMUNITIES: 0:7119 ! result: 7119
telnet at 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!