On Oct 6, 2005, at 2:57 PM, Richard A Steenbergen wrote:
On Thu, Oct 06, 2005 at 01:59:01PM -0400, Patrick W. Gilmore wrote:
You are mistaken.
If I sent 100 Gbps outbound and 20 inbound, I can sell 40-60 Gbps of additional inbound for FAR, FAR less than 40-60 Gbps of additional outbound.
Zero cost? Probably not. Trivial cost? Possibly, depends on network.
Patrick, I keep telling you, you are not an ISP. :)
Ha, ha.
Yes clearly there is SOME reduction in equipment cost at the edge, you need to buy fewer peering and transit ports if there is available capacity on a full duplex circuit in the opposite direction. You may also see some savings on the customer edge where you are utilizing the extra capacity in the opposite direction on trunk ports out of your aggregation layer.
Unfortunately in the core traffic is traffic, and you usually don't see such an obvious "but I have this extra capacity in the other direction" pattern. The opex cost of hauling the bits that other folks hot potato onto you is going to quickly negate the capex cost of the equipment. I know you don't deal with this, since as we've already established you are not an ISP, but the cost of longhaul circuits (even very large and well negotiated ones between major cities on major routes) is huge. The cost per meg to get a bit from one side of the US to the other is roughly equal to or above what people are selling transit for per meg these days, and in many cases that doesn't take into account non-perfect utilization and the need for backup capacity on diverse paths. There is nothing trivial about this cost for an actual network, and this completely different from using a rule of 95th percentile billing to squeeze some extra service out of someone else's network for free.
Please note the "Possibly, depends on network" comment. There are ABSOLUTELY networks where their backbone circuits are empty but their tail circuits to the peering locations are used in one direction. There are networks which have cities / POPs / regions pushing or pulling more than the opposite. There are lots & lots of various configurations where you can plop down a sink or a source and know that they will be utilizing unused resources. Doing so, and selling it at a discount, is simply good business. Sorry if your network isn't like that, but that doesn't make it so for everyone. Oh, and I'd argue you ain't an ISP either. :) -- TTFN, patrick