Routers in Data Centers

Richard A Steenbergen ras at
Mon Sep 27 02:29:07 UTC 2010

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. :)

> 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)

More information about the NANOG mailing list