Layer 2 vs. Layer 3 to TOR

George Bonser gbonser at
Thu Nov 12 22:46:49 UTC 2009

I believe the issue will become a moot point in the next 12 months when
vendors begin to ship switches with TRILL.

TRILL is basically a layer 2 routing protocol that will replace spanning
tree.  It will allow you to connect several uplinks, utilize all the
bandwidth of the uplinks, prevent loops, and find the best path to the
destination through the switch fabric.  Think of it like OSPF for layer

It should be shipping within the next 6 to 9 months.

-----Original Message-----
From: Raj Singh [mailto:raj.singh at] 
Sent: Thursday, November 12, 2009 11:49 AM
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

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