|
North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: Cost per prefix [was: request for help w/ ATT and terminology]
On Jan 20, 2008, at 8:46 PM, William Herrin wrote: So at this point, the part of my analysis you still dispute is where I claimed that 75% of the $40k cost of an entry-level DFZ router was attributable to its ability to carry the needed prefix count. As I said before, your calculation is in error. I very clearly explained why, but you threw out my explanation below. Apparently I assumed you had knowledge you did not. Please forgive me for not assuming you were ignorant. I shall not repeat my mistake. For example, the Cisco 3750G has all of features except for the ability to hold 300k+ prefixes. Per CDW, the 48-port version costs $10k, so the difference (ergo cost attributable to prefix count) is $40k-$10k=$30k, or 75%. Unfortunately, I have to run real packets through a real router in the real world, not design a network off CDW's website. As a simple for-instance, taking just a few thousand routes on the 3750 and trying to do multipath over, say 4xGigE, the 'router' will fail and you will see up to 50% packet loss. This is not something I got off CDW's website, this is something we saw in production. And that's without ACLs, NetFlow, 100s of peering sessions, etc. None of which the 3750 can do and still pass gigabits of traffic through a layer 3 decision matrix. Have you ever configured a 3750 to do BGP with a few gigabits running through it? A 7600? I submit that you probably have not. And you certainly have not done it in any but the most basic of configurations or you would not have posted this silliness. Or you can keep swimming in that river in Egypt. Its up to you. William, if that's the best flame you can come up with, perhaps I should stop reading your posts. Then again, given you honestly believe the only difference between a 3750 & a 7600 is the # of prefixes it can take, I'm not sure why I am still reading your posts. On Jan 20, 2008 5:10 PM, Patrick W. Gilmore <[email protected]> wrote:On Jan 20, 2008, at 3:34 PM, William Herrin wrote:( [entry level router's cost attributable to prefixes]/[expected lifespan] ) / [DFZ prefix count] We disagree. What's more, this thing called "the real world" disagrees as well. The dividing line between the two classes of equipment is in the 8k-16k prefix range. Thus your statement is like saying, "If you drop the towing weight from 900 lbs to 200lbs, the 1000lb tow cable is still not functionally equivalent to a 100lb tow cable." That has something of a high "duh" factor. If you dropped the prefix count to 8k instead of 250k, the two pieces of equipment (virtual chassis stack, entry level DFZ router) would be equivalent for most DFZ router scenarios in which an entry-level DFZ router is used. Drop it to 8K prefixes, then see example above. Drop it to 2 prefixes (local LAN + default), the two routers are still not equivalent. I'm certain there are networks who would (do?) use 3750s if the v4 table were the size of the v6 table. But they tend to be smaller networks, with few or no BGP customers, and not much traffic. No 'tier one' network would, and most networks their size would not. Most networks half their size would not. Have you ever seen the requirements put on a peering or customer aggregation router at a large network? I really do not have time to explain why if you do not already know. I've spent too much time trying to explain it to you already, yet I seem to be failing at explanations, and you just send me (pathetic) flames back anyway. Perhaps some other poster can explain it to you. For cost analysis purposes, you need only consider a true/false condition here: Would that the world were so simple. -- TTFN, patrick
|