Routers in Data Centers

Christian Martin christian.martin at
Mon Sep 27 02:46:48 UTC 2010

On Sep 26, 2010, at 10:29 PM, Richard A Steenbergen <ras at> wrote:

> On Sun, Sep 26, 2010 at 09:24:54PM -0400, Alex Rubenstein wrote:
>> And, not to mention that some vendors do it sometimes.
>> "The 9-slot Cisco Catalyst 6509 Enhanced Vertical Switch (6509-V-E) 
>> provides [stuff]. It also provides front-to-back airflow that is 
>> optimized for hot and cold aisle designs in colocated data center and 
>> service provider deployments and is compliant with Network Equipment 
>> Building Standards (NEBS) deployments."
> A classic 6509 is under 15U, a 6509-V-E is 21U. Anyone can do front to 
> back airflow if they're willing to bloat the size of the chassis (in 
> this case by 40%) to do all the fans and baffling, but then you'd have 
> people whining about the size of the box. :)

I would point out that it is quite possible to build a compact (say 4-5 U) front-back airflow platform if vendors were willing to pay to engineer a small midplane and leverage modular I/O cards in a single vertical arrangement.  As an example, envisage an M10i with 8 single height PIC slots, rear mounted RE/PFE combos, and a top/bottom impeller.  Same for a 72/73xx, or whatever platform you fancy.  But would it make business sense?  You'd lose rack space in favor of thermal efficiency.  

I think the push toward cloud computing and the re-emergence of big datacenters with far more stringent power and heat restrictions may actually drive such a move.   I guess we'll see...


>> It only took 298 years from the inception of the 6509 to get a 
>> front-to-back version. If you can do it with that oversized thing, it 
>> certainly can be done on a 7200, XMR, juniper whatever, or whatever 
>> else you fancy.
> Well, a lot of people who buy 7200s, baby XMRs, etc, are doing it for 
> the size. Lord knows I certainly bought enough 7606s instead of 6509s 
> over the years for that very reason. I'm sure the vendors prefer to 
> optimize the size footprint on the smaller boxes, and only do front to 
> back airflow on the boxes with large thermal loads (like all the modern 
> 16+ slot chassis that are rapidly approaching 800W/card). Also, remember 
> the 6509 has been around since its 9 slots were lucky to see 100W/card, 
> which is a far cry from a box loaded with 6716s at 400W/card or other 
> power hungry configs.
> Remember the original XMR 32 chassis, which had side to side airflow? 
> They quickly disappeared that sucker and replaced it with the much 
> larger version they have today, I can only imagine how bad that was. :)
> -- 
> Richard A Steenbergen <ras at>
> GPG Key ID: 0xF8B12CBC (7535 7F59 8204 ED1F CC1C 53AF 4C41 5ECA F8B1 2CBC)

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