There are mods / addons available for WHMCS that offer this. Check the WHMCS forums and you will see a couple of them available. They work well, I have persoanlly used a couple of them in WHMCS.
You can also setup bandwidth graphs in WHMCS rather easily using cacti and simple template mods .
The full feature set available with Ubersmith's device manager and IP management is hard to replicate in something like WHMCS, but the basic reboot and bandwidth graphing is easily had.
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