From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Lunn Subject: Re: cascaded switch Date: Fri, 18 May 2018 22:29:20 +0200 Message-ID: <20180518202920.GI23100@lunn.ch> References: <20180518191357.GH23100@lunn.ch> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: netdev@vger.kernel.org To: Ran Shalit Return-path: Received: from vps0.lunn.ch ([185.16.172.187]:37201 "EHLO vps0.lunn.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751897AbeERU3W (ORCPT ); Fri, 18 May 2018 16:29:22 -0400 Content-Disposition: inline In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: > Hi, > > I mean the same terminology used in marvell's switch.(I don't think > there is more than one terminology for this, please correct me if > wrong). > Anyway, I can see examples how it is done, but I don't understand the > benefit of this constellation, and why device tree needs to be > familiar with it. > > < switch 1 >---port10--------port10- < switch 2 > > | ....| | | ....| | > port 1-9 | port 1-9 | > | | > | | > --mdio---------------------------------------------- Your ASCII art is all messed up, but i get what you mean. This is the D in DSA. You would use this when a single switch does not have enough ports for your use case. So you use two switches. You need to tell each switch what links are used to get to other switches. There is an internal routing table. So you need to describe these links in device tree. Andrew