Layer 2 vs. Layer 3 to TOR

Raj Singh raj.singh at
Thu Nov 12 20:04:06 UTC 2009

We are actually looking at going Layer 3 all the way to the top of rack and make each rack its own /24. This provides us flexibility when doing maintenance (spanning-tree). Also, troubleshooting during outages is much easier by using common tools like ping and trace routes.

I want to make sure this is something other people are doing out there and want to know if anyone ran into any issues with this setup.

Raj Singh   |    Director Network Engineering
Demand Media | eNom, Inc.
Direct: 425.974.4679
15801 NE 24th St.
Bellevue, WA 98008
Raj.Singh at

-----Original Message-----
From: Paul Stewart [mailto:pstewart at] 
Sent: Thursday, November 12, 2009 11:53 AM
To: Raj Singh; nanog at
Subject: RE: Layer 2 vs. Layer 3 to TOR

We are heading towards that type of deployment beginning next year with
Juniper EX4200 switches in a redundant configuration.  This will be pure
Layer2 in nature on the switches and they will "uplink" to Juniper
M10i's for layer3... the power savings, space savings etc over
traditional Cisco 6500 chassis (plus all the cabling between cabinets
which is in our case a nightmare) made this a pretty easy choice... and
price too..;)

Somewhere on Juniper's website in the product info section they have
deployment whitepapers on this kind of stuff if that's of interest....

Hope this helps..


-----Original Message-----
From: Raj Singh [mailto:raj.singh at] 
Sent: November-12-09 2:49 PM
To: 'nanog at'
Subject: Layer 2 vs. Layer 3 to TOR


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?

Raj Singh



"The information transmitted is intended only for the person or entity to which it is addressed and contains confidential and/or privileged material. If you received this in error, please contact the sender immediately and then destroy this transmission, including all attachments, without copying, distributing or disclosing same. Thank you."

More information about the NANOG mailing list