My personal feeling is that the provision of service should be implemented on a separate port of the ISP's router - this provides both the ISP and the web farmer with a measurable point of demarcation
My personal feeling is that any Unix machines should be provisioned on separate IP space from the routers. And that perhaps a default- monitoring program (which we run ourselves anyway) might be run to make sure that the machines aren't defaulting to anyone if the machines are hooked up to the same switched fabric as the routers (which I think is a bad idea). I'm not arguing that getting transit via an XP fabric is a bad idea - as long as the XP provider gets beefy enough switching and as long as the transit providers have enough ports into their routers from the XP fabric, it's a fine idea - much better than lots of rack-rack cables. But boxes w/ hard drives are a different story IMO.
independent of the IX. If the web farmer paid for an Ethernet or whatever interface, they'd get an Ethernet or whatever interface, and the bandwidth available to the customer on that port would not vary with other traffic as it would if the web farmer were competing with the ISP's peers for an interface attached to the GIGAswitch. Should the web farmer purchase connectivity from other ISPs, their purchases can be implemented as cross-connects to ISP routers (assuming the address space can be advertised, the topology of the web farmer's network can handle it, etc., etc., etc.).
ISPs might also wish to implement certain peering relationships with cross-connects rather than consume bandwidth on their interface to the GIGAswitch. To us, cross-connects are cross-connects, whether they connect ISPs to web farmers or ISPs to ISPs.
Stephen
Avi