IOS is the operating system of cisco routers and switches. The name is a acronym for Internetworking Operating System. Usually you access it by telnet.  It is unix based operating system and everyone that know unix feels at home when telnetting into cisco router. Good resourse about the cisco IOS commands is:

http://www.cisco.com/univercd/cc/td/doc/product/software/ios120/12cgcr/rbkixol.htm

The ping commmand in cisco ios is divited into simple and extended ping. 

With simple ping you can ping one ip address. With extended ping you can use the ping for measuring many things other than simple conectivity between ip adresses. For example you can change the packet size.  A good webpage deschribing how extended ping works and the possibilities that you can use is

http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080093f22.shtml