Date: Thu, 3 Jul 2014 09:31:45 +0100 From: Nikolay Denev <ndenev@gmail.com> To: Kevin Oberman <rkoberman@gmail.com> Cc: Sreenivasa Honnur <shonnur@chelsio.com>, FreeBSD Current <freebsd-current@freebsd.org>, Slawa Olhovchenkov <slw@zxy.spb.ru> Subject: Re: FreeBSD iscsi target Message-ID: <CA%2BP_MZE013dv22Sb-rk7ZoiYbCTodmth0d-XpdM6mrpw3WxQmg@mail.gmail.com> In-Reply-To: <CAN6yY1von-Z586V=8qs3%2BOfV3oXes380s2GD-149EYWLxws-qA@mail.gmail.com> References: <20140626232727.GB1825@pwnie.vrt.sourcefire.com> <53ACE5B4.8070700@rice.edu> <CAPjTQNEsQGDHdApx0-=h63QN4o=zXKen0Y_6Ehj9_isfgac9tw@mail.gmail.com> <F2BBBB6E0068844991318A316F34795C390447@nice.asicdesigners.com> <20140701091252.GB3443@brick> <20140701231305.GA37246@zxy.spb.ru> <CAN6yY1t2qDzfeO37p2s_3=vzEVv5C813M0ttqjnM4tJGkkBhyA@mail.gmail.com> <20140702112609.GA85758@zxy.spb.ru> <CAN6yY1uzfjoDfEdti91Ogy11LzT3-5JvLREBdW6ynEOgm0uUPA@mail.gmail.com> <20140702203603.GO5102@zxy.spb.ru> <CAN6yY1von-Z586V=8qs3%2BOfV3oXes380s2GD-149EYWLxws-qA@mail.gmail.com>
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On Thu, Jul 3, 2014 at 12:06 AM, Kevin Oberman <rkoberman@gmail.com> wrote: > On Wed, Jul 2, 2014 at 1:36 PM, Slawa Olhovchenkov <slw@zxy.spb.ru> 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 <slw@zxy.spb.ru> >> 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 <slw@zxy.spb.ru> >> > > 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 <https://en.wikipedia.org/wiki/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 --Nikolay
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