is that large companies spending lots on capex that they must do to keep all the high bandwidth offerings alive (video etc.) like YouTube rarely have single source suppliers. For the core internet, the largest supplier is Cisco and the most technically advanced is Juniper, and frankly there are few other 'real' contenders. So if you're a telco, and you're buying (which you need to) you're spending on Juniper. Also, since their kit currently has an edge, they are gaining market share.
So it's a nice way to play a solid trend, the hard bit is choosing how high Juniper will go....