iproute is a package used for TrafficShaping and as an interface to NetEm typically through the use of the program tc. /sbin/ip is one of the applications in this package and it uses LinuxNetlinkSockets
The home page for this is at 
http://linux-net.osdl.org/index.php/Iproute2
See also iproute(7) or, much better, ip(8).
Part of NetworkingUtilities
3 pages link to IpRoute:
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