From owner-freebsd-current@FreeBSD.ORG Thu Jul 3 09:13:27 2014 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 8733A3BE for ; Thu, 3 Jul 2014 09:13:27 +0000 (UTC) Received: from zxy.spb.ru (zxy.spb.ru [195.70.199.98]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 3B6D42E4D for ; Thu, 3 Jul 2014 09:13:26 +0000 (UTC) Received: from slw by zxy.spb.ru with local (Exim 4.82 (FreeBSD)) (envelope-from ) id 1X2d4z-000K0o-JA; Thu, 03 Jul 2014 13:13:21 +0400 Date: Thu, 3 Jul 2014 13:13:21 +0400 From: Slawa Olhovchenkov To: Nikolay Denev Subject: Re: FreeBSD iscsi target Message-ID: <20140703091321.GP5102@zxy.spb.ru> References: <20140701091252.GB3443@brick> <20140701231305.GA37246@zxy.spb.ru> <20140702112609.GA85758@zxy.spb.ru> <20140702203603.GO5102@zxy.spb.ru> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) X-SA-Exim-Connect-IP: X-SA-Exim-Mail-From: slw@zxy.spb.ru X-SA-Exim-Scanned: No (on zxy.spb.ru); SAEximRunCond expanded to false Cc: Kevin Oberman , Sreenivasa Honnur , FreeBSD Current X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 03 Jul 2014 09:13:27 -0000 On Thu, Jul 03, 2014 at 09:31:45AM +0100, Nikolay Denev wrote: > On Thu, Jul 3, 2014 at 12:06 AM, Kevin Oberman wrote: > > On Wed, Jul 2, 2014 at 1:36 PM, Slawa Olhovchenkov wrote: > > > >> On Wed, Jul 02, 2014 at 12:51:59PM -0700, Kevin Oberman wrote: > >> > >> > On Wed, Jul 2, 2014 at 4:26 AM, Slawa Olhovchenkov > >> wrote: > >> > > >> > > On Tue, Jul 01, 2014 at 10:43:08PM -0700, Kevin Oberman wrote: > >> > > > >> > > > On Tue, Jul 1, 2014 at 4:13 PM, Slawa Olhovchenkov > >> > > wrote: > >> > > > > >> > > > > On Tue, Jul 01, 2014 at 11:12:52AM +0200, Edward Tomasz Napierala > >> > > wrote: > >> > > > > > >> > > > > > Hi. I've replied in private, but just for the record: > >> > > > > > > >> > > > > > On 0627T0927, Sreenivasa Honnur wrote: > >> > > > > > > Does freebsd iscsi target supports: > >> > > > > > > 1. ACL (access control lists) > >> > > > > > > >> > > > > > In 10-STABLE there is a way to control access based on initiator > >> > > > > > name and IP address. > >> > > > > > > >> > > > > > > 2. iSNS > >> > > > > > > >> > > > > > No; it's one of the iSCSI features that seem to only be used > >> > > > > > for marketing purposes :-) > >> > > > > > > >> > > > > > > 3. Multiple connections per session > >> > > > > > > >> > > > > > No; see above. > >> > > > > > >> > > > > I think this is help for 40G links. > >> > > > > > >> > > > > >> > > > I assume that you are looking at transfer of large amounts of data > >> over > >> > > 40G > >> > > > links. Assuming that tis is the case, yes, multiple connections per > >> > > session > >> > > > >> > > Yes, this case. As I know, single transfer over 40G link limited by > >> > > 10G. > >> > > > >> > ??? No, not at all. Getting 40G performance over TCP is not easy, but > >> there > >> > is no 10G limitation. > >> > >> As I know (may be wrong) 40G is bundled 4x10G link. > >> For prevent packet reordering (when run over diferrent link) all > >> packets from one sessoin must be routed to same link. > >> Same issuse for Etherchannel. > >> > > > > No, 40G Ethernet is single channel from the interface perspective.. What > > my be confusing you is that they may use "lanes" which, for 40G, are > > 10.3125G. But, unlike the case with Etherchannel, these lanes are "hidden" > > from the MAC. The interface deals with a single stream and parcels it out > > over the 10G (or 25G) lanes. All 100G optical links use multiple lanes > > (4x25G or 10x10G), but 40G my use either a single 40G lane for distances of > > up to 2km or 4x10G for longer runs. > > > > Since, in most cases, 40G is used within a data center or to connect to > > wave gear for DWDM transmission over very long distances, most runs are > > under 2km, so a single 40G lane may be used. When 4 lanes are used, a > > ribbon cable is required to assure that all optical or copper paths are > > exactly the same length. Since the PMD is designed to know about and use > > these lanes for a single channel, the issue of packet re-ordering is not > > present and the protocol layers above the physical are unaware of how many > > lanes are used. > > > > Wikipedia has a fairly good discussion under the unfortunate title of 100 > > Gigabit Ethernet . > > Regardless of the title, the article covers both 40 and 100 Gigabit > > specifications as both were specified on the same standard, 802.3ba. > > > > -- > > R. Kevin Oberman, Network Engineer, Retired > > E-mail: rkoberman@gmail.com > > _______________________________________________ > > freebsd-current@freebsd.org mailing list > > http://lists.freebsd.org/mailman/listinfo/freebsd-current > > To unsubscribe, send any mail to "freebsd-current-unsubscribe@freebsd.org" > > I found this white paper useful in understanding how this works : > http://www.cisco.com/c/en/us/products/collateral/switches/nexus-3000-series-switches/white_paper_c11-726674.pdf In real world "Reality is quite different than it actually is". http://www.cisco.com/c/en/us/products/collateral/switches/catalyst-6500-series-switches/white_paper_c11-696669.html See "Packet Path Theory of Operation. Ingress Mode".