From: Sean Doran <smd@icp.net> To: pferguso@cisco.com, salo@msc.edu Subject: Re: sell shell accounts? Cc: nanog@merit.edu Date: Wed, 24 Jul 1996 01:43:30 +0100
| o Given that each link is rather expensive, it behooves the | NSP to try to avoid needlessly moving a packet back and | forth across a DS-3 local loop just because my ATM | provider can't provide me with any more PVCs. | (Which was my major point, by the way.)
Interestingly enough, the NSPs I observe moving large amounts of traffic around are set up in such a way that their routers are generally colocated with carrier transmission gear, and so there *is* no local loop to speak of, as an added cost to an outside supplier. [...]
Hopefully, my thinking is clearer than my writing... What I originally called "local loop B," now relabeled "This Thing Here," is probably comprised of: o a port on the ATM switch/service o a connection between the router and the switch, (usually a wide-area link, given that most wide-area ATM services backhaul traffic to a few ATM switches) o a port on the router A short-cut VC would avoid needlessly passing packets back and forth across "This Thing Here." That would seem to be a good thing in most circumstances, inasmuch as some or all of the components of "This Thing Here" cost something and may potentially become a bottleneck. -tjs | ________ _______________________ ________ | | Router | loop A | | loop C | Router | | | A |=========| Wide-Area ATM Service |========| C | | |________| |_______________________| |________| | | | | <=== This Thing Here | | | ________ | | Router | | | B | | |________|