"IS-IS" is IGP; most typically seen in ISP networks.
If you are deploying IGP in Enterprise network, most typically you would be using OSPF, EIGRP or BGP.
PS:
http://www.cisco.com/c/en/us/td/docs/ios/12_2/ip/configuration/guide/1cfisis.html
http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/iproute_isis/configuration/12-4t/irs-12-4t-book.pdf