Cost per prefix [was: request for help w/ ATT and terminology]

Patrick W. Gilmore patrick at ianai.net
Sun Jan 20 22:10:32 UTC 2008


On Jan 20, 2008, at 3:34 PM, William Herrin wrote:

>> The difference is much, much, much greater than that.  Can the switch
>> do ACLs?  Policy routing?  SFlow with the same sampling rate?  Same
>> number of BGP session?
>
> Is there some alternate piece of cheap hardware that supports the DFZ
> prefix count at high data rates but doesn't have those features? If
> the answer is no (and I'm pretty sure the answer is no), then the
> prefix count remains the proper attribution for the cost delta.

We still disagree.

I notice you cut out the next two sentences:

<quote>
In short, if the table were 50K prefixes instead of 250K, would these  
pieces of equipment be equivalent?  The answer is a blatant "no".
</quote>

If we take out the "proper attribution for the cost delta" out of the  
equation and the equipment is still not considered equal, I submit  
your idea of "proper attribution" is, well, not proper.

To be clear, of course there are some people who could use either if  
the table were 50K prefixes.  But the majority of routers in the DFZ  
cannot be replaced by cheap 1U (or whatever) switches which can do a  
few 10s of 1000s of prefixes.  (Besides, the people who _can_ use them  
can use them today with properly configured filters, perhaps on the  
upstream router's side.  Which, of course, means the upstream router  
cannot be one of those cheap switches. :)

Perhaps you should justify numbers with nine zeros a little better  
before asking me to justify why they are wrong.

-- 
TTFN,
patrick




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