From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joakim Tjernlund Subject: Re: DSA vs. SWTICHDEV ? Date: Wed, 30 Nov 2016 17:44:14 +0000 Message-ID: <1480527852.3563.146.camel@infinera.com> References: <1480495831.3563.135.camel@infinera.com> <20161130135257.GC18716@lunn.ch> <1480516241.3563.142.camel@infinera.com> <20161130152503.GE21645@lunn.ch> <1480523716.3563.144.camel@infinera.com> <20161130165500.GH21645@lunn.ch> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-15" Content-Transfer-Encoding: quoted-printable Cc: "netdev@vger.kernel.org" To: "andrew@lunn.ch" Return-path: Received: from mail-co1nam03on0043.outbound.protection.outlook.com ([104.47.40.43]:28257 "EHLO NAM03-CO1-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752789AbcK3SAf (ORCPT ); Wed, 30 Nov 2016 13:00:35 -0500 In-Reply-To: <20161130165500.GH21645@lunn.ch> Content-Language: en-US Content-ID: <22B2C4AC2FBA7344B429E3E32EC3A3A3@infinera.com> Sender: netdev-owner@vger.kernel.org List-ID: On Wed, 2016-11-30 at 17:55 +0100, Andrew Lunn wrote: > > This is an embedded system with several boards in a subrack. > > Each board has eth I/F connected to a switch to communicate with each o= ther. > > One of the board will also house the actual switch device and manage th= e switch. > > Then the normal app just communicates over the physical eth I/F like an= y other board > > in the system. There is a "manage switch app" which brings the switch u= p and partition > > phys VLANs etc. (each phys I/F would be a a separate domain so no loop) >=20 > So you are planning on throwing away the "manage switch app", and just > use standard linux networking commands? That is what switchdev is all > about really, throwing away the vendor SDK for the switch, making a > switch just a bunch on interfaces on the host which you manage as > normal interfaces. Something like that. I need to run routing protocols on the switch I/Fs and= egress pkgs on selected switch I/Fs bypassing ARP, just like DSA does with its ven= dor tags. >=20 > > I guess I could skip the phys I/F and have the switch app create a virt= ual eth0 I/F over PCIe >=20 > No need to create this interface. It will exist if you go the > switchdev route. >=20 > > > > And switchdev can do all this over PCIe instead? Can you have a > > > > switch tree in switchdev too? > > >=20 > > > Mellonex says so, but i don't think they have actually implemented it= . > >=20 > > Not impl. any of DSAs features? What can you do with a Mellonex switch = then? >=20 > They don't have a tree of switches, as far as i know. Just a single > switch. But DSA does support a tree of switches, that is what the D in > DSA means, distributed. And there are a couple of boards which have 2 > to 4 switches in a tree. We might have a tree as well so now I really wonder: Given we write a proper switchdev driver, can it support switchtrees without touching switchdev infra structure? If not I guess we will attach a physical eth I/F to the switch and use both DSA and switchdev to support both trees and HW offload.=20 >=20 > I think this is partially down to market segments. Mellonex market is > top of rack switches. High port count, very high bandwidth. DSA is > more wireless access points, set top boxes, generally up to 7 ports of > 1Gbps and a few custom embedded products which need more ports, so > build a tree of switches. We have on an existing board with a BCM ROBO switch with lots of ports(>24)= , managed over SPI. Looking at BCM DSA tag code it looks like it only support= s some 8 ports or so. I still have to find out if this is a limitation in BCM= tagging protocol or if just not impl. in DSA yet.