Layer 2 vs. Layer 3 to TOR

Bulger, Tim Tim_Bulger at
Thu Nov 12 20:40:26 UTC 2009

If you use stackable switches, you can stack across cabinets (up to 3 with 1 meter Cisco 3750 Stackwise), and uplink on the ends.  It's a pretty solid layout if you plan your port needs properly based on NIC density and cabinet size, plus you can cable cleanly to an adjacent cabinet's switch if necessary.

Slightly off-topic.. Consider offloading 100Mb connections like PDUs, DRAC/iLO, etc. to lower cost switches to get the most out of your premium ports.


-----Original Message-----
From: Seth Mattinen [mailto:sethm at] 
Sent: Thursday, November 12, 2009 3:20 PM
To: 'nanog at'
Subject: Re: Layer 2 vs. Layer 3 to TOR

Steve Feldman wrote:
> On Nov 12, 2009, at 2:48 PM, Raj Singh wrote:
>> Guys,
>> I am wondering how many of you are doing layer 3 to top of rack
>> switches and what the pros and cons are. Also, if you are doing layer
>> 3 to top of  rack do you guys have any links to published white papers
>> on it?
> Dani Roisman gave an excellent talk on this subject at NANOG 46 in
> Philadelpha:

I'd always wondered how you make a subnet available across racks with L3
rack switching. It seems that you don't.


More information about the NANOG mailing list