From mboxrd@z Thu Jan 1 00:00:00 1970 From: Roopa Prabhu Subject: Re: [patch iproute2 1/6] iproute2: ipa: show switch id Date: Thu, 04 Dec 2014 09:59:02 -0800 Message-ID: <5480A0E6.3050301@cumulusnetworks.com> References: <1417683438-10935-1-git-send-email-jiri@resnulli.us> <1417683438-10935-2-git-send-email-jiri@resnulli.us> <87y4qne6if.fsf@x220.int.ebiederm.org> <20141204163024.GG1861@nanopsycho.orion> <87388v9ua6.fsf@x220.int.ebiederm.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Jiri Pirko , netdev@vger.kernel.org, davem@davemloft.net, nhorman@tuxdriver.com, andy@greyhouse.net, tgraf@suug.ch, dborkman@redhat.com, ogerlitz@mellanox.com, jesse@nicira.com, pshelar@nicira.com, azhou@nicira.com, ben@decadent.org.uk, stephen@networkplumber.org, jeffrey.t.kirsher@intel.com, vyasevic@redhat.com, xiyou.wangcong@gmail.com, john.r.fastabend@intel.com, edumazet@google.com, jhs@mojatatu.com, sfeldma@gmail.com, f.fainelli@gmail.com, linville@tuxdriver.com, jasowang@redhat.com, nicolas.dichtel@6wind.com, ryazanov.s.a@gmail.com, buytenh@wantstofly.org, aviadr@mellanox.com, nbd@openwrt.org, alexei.starovoitov@gmail.com, Neil.Jerram@metaswitch.com, ronye@mellanox.com, simon.horman@netronome.com, alexander.h.duyck@redhat.com, john.ronciak@intel.com, mleitner@redhat.com, shrijeet@gmail.com, gospo@cumulusnetworks.com, bcrl@kvack.org, hemal@broadc To: "Eric W. Biederman" Return-path: Received: from ext3.cumulusnetworks.com ([198.211.106.187]:56216 "EHLO ext3.cumulusnetworks.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932455AbaLDR7c (ORCPT ); Thu, 4 Dec 2014 12:59:32 -0500 In-Reply-To: <87388v9ua6.fsf@x220.int.ebiederm.org> Sender: netdev-owner@vger.kernel.org List-ID: On 12/4/14, 9:52 AM, Eric W. Biederman wrote: > Jiri Pirko writes: > >> Thu, Dec 04, 2014 at 05:15:04PM CET, ebiederm@xmission.com wrote: >>> Jiri Pirko writes: >>> >>> Would someone please explain to me what a switch id is? >>> >>> I looked in the kernel source, and I looked here and while I know >>> switches I don't have a clue what a switch id is. >>> >>> My primary concern at this point is that you have introduced a global >>> identifier that is isn't a hardware property (it certainly does not look >>> like a mac address) and that is unique across network namespaces and >>> thus breaks checkpoint/restart (aka CRIU). >> IFLA_PHYS_SWITCH_ID is very similar to IFLA_PHYS_PORT_ID. It is >> generated by the driver and ensures that there is the same switch id for >> all ports belonging to the same switch chip/asic. It is up to the driver >> how to implement the id. I would like to point you to driver >> implementing ndo_get_phys_port_id > Looking at ndo_get_phys_port_id it is just the per port mac address. Or > guid in the case of infiniband. Which really makes me wonder why we > didn't use the same abstractions in the code for address types that we > do for hardware addresses. > > Using mac address or other hardware addresses that are used for layer 2 > addressing makes sense to me. There is a long tradition of that and as > I recall protocols like STP actually requiring having a different mac > address per port. > > When I asked the question I thought the switch id was going to be > something like the ifindex, the software index of a network device. > > > Finally having tracked down the rocker implementation of > rocker_port_switch_parent_id_get I see it you are reading some 64bit > hardware register. > > Which leads me to ask what are the semantics of switch_id? > > Is the switch id an identifier with a prefix from IEEE and assigned by > the manufacture so that it is guaranteed to the tolerances of the > manufacturing process to be globally unique? > > Is the switch id a random number that is statistically likely to be > globally unique because you have enough bits? As I recall you need > at least 128 bits to have a reasonable chance of a random number > avoiding the birthday paradox. > > Do we need some kind of manufacturer id to tell one switch id from > another? > > Is the switch id persistent across reboots? > >>> Also what in the world does PHYS mean in IFLA_PHYS_SWITCH_ID? Does that >>> mean we can't have a purely software implementation of this interface? >>> Given that we will want a software implementation at some point >>> including PHYS in the name seems completely wrong. >> We can remove the "PHYS", no problem. I do not understand what you say >> about "software implementation". The point is to allow hw switch/ish >> chips to be supported. > If we are talking about something typically stored in a eeprom like a > mac address phys seems appropriate. > > Still having a definition of this switch id clean clear enough that > net/bridge and drivers/net/macvlan can implement it seems important. > > Even more important is having a definition of switch id clear enough > that userspace can use the switch id to do something useful. > > Right now switch id looks like one of those weird one manufacturer > properties that is fine to expose as a driver specific property > but I don't yet see it being a generic property I that can be used > usefully in userspace. > > So can we please get some clear semantics or failing that can we please > not expose this to userspace as generic property. Agree..100%. This was my original concern as well and i have raised it earlier. Don't expose it to userspace if the semantics are still not clear. Thanks. >>>> Signed-off-by: Jiri Pirko >>>> --- >>>> include/linux/if_link.h | 1 + >>>> ip/ipaddress.c | 8 ++++++++ >>>> 2 files changed, 9 insertions(+) >>>> >>>> diff --git a/include/linux/if_link.h b/include/linux/if_link.h >>>> index 4732063..a6e2594 100644 >>>> --- a/include/linux/if_link.h >>>> +++ b/include/linux/if_link.h >>>> @@ -145,6 +145,7 @@ enum { >>>> IFLA_CARRIER, >>>> IFLA_PHYS_PORT_ID, >>>> IFLA_CARRIER_CHANGES, >>>> + IFLA_PHYS_SWITCH_ID, >>>> __IFLA_MAX >>>> }; >>>> >>>> diff --git a/ip/ipaddress.c b/ip/ipaddress.c >>>> index 4d99324..bd36a07 100644 >>>> --- a/ip/ipaddress.c >>>> +++ b/ip/ipaddress.c >>>> @@ -589,6 +589,14 @@ int print_linkinfo(const struct sockaddr_nl *who, >>>> b1, sizeof(b1))); >>>> } >>>> >>>> + if (tb[IFLA_PHYS_SWITCH_ID]) { >>>> + SPRINT_BUF(b1); >>>> + fprintf(fp, "switchid %s ", >>>> + hexstring_n2a(RTA_DATA(tb[IFLA_PHYS_SWITCH_ID]), >>>> + RTA_PAYLOAD(tb[IFLA_PHYS_SWITCH_ID]), >>>> + b1, sizeof(b1))); >>>> + } >>>> + >>>> if (tb[IFLA_OPERSTATE]) >>>> print_operstate(fp, rta_getattr_u8(tb[IFLA_OPERSTATE]));