I might be misremembering, and some of those folks may have moved on, but Comcast inherited a large portion of the '@home' cable modem network, which was, as fa

I might be misremembering, and some of those folks may have moved on, but Comcast inherited a large portion of the '@home' cable modem network, which was, as far as I know, the first network to run out of RFC1918 space due to size and not horrible management. You can't grow a network that large without knowing your stuff inside and out. The netops folks at comcast are fairly active in NANOG, etc. as well.