Re: [trill] 答复: Explaining three options for upgrading to FGL (fine-grained-labeling)
Radia Perlman <radiaperlman@gmail.com> Fri, 01 February 2013 10:45 UTC
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Date: Fri, 01 Feb 2013 02:45:30 -0800
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From: Radia Perlman <radiaperlman@gmail.com>
To: Haoweiguo <haoweiguo@huawei.com>
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Cc: Anoop Ghanwani <anoop@alumni.duke.edu>, Ayan Banerjee <ayabaner@gmail.com>, Sam Aldrin <aldrin.ietf@gmail.com>, Donald Eastlake <d3e3e3@gmail.com>, "trill@ietf.org" <trill@ietf.org>, "Tissa Senevirathne (tsenevir)" <tsenevir@cisco.com>, Jon Hudson <jon.hudson@gmail.com>
Subject: Re: [trill] 答复: Explaining three options for upgrading to FGL (fine-grained-labeling)
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I think you were just misinterpreting what I wrote. It is OK to let things through that could be pruned. It is *not* OK to falsely delete things. The example I gave of interpreting the first FGL label as a VL label is something that the RBridge MUST NOT do. So we're not disagreeing. Radia On Fri, Feb 1, 2013 at 1:11 AM, Haoweiguo <haoweiguo@huawei.com> wrote: > Hi Radia, > > I agree with your definition of "Safe FGL",but I have a problem about the > following point: > > > b) multicast pruning: it's OK not to do pruning at all, or to actually > look at all 24 bits of the FGL and prune as a proper FGL guy would do. But > an example of what you canNOT do is look at the first 12 bits of FGL, > pretend it's the same as VL, and delete the multicast packet because nobody > downstream is listening to that 12 bit VL value > > [weiguo]:If a switch performs pruning by first 12 bits of FGL, can the > switch called "Safe FGL" switch? If downstream have one VL switch with VLAN > is equal to first 12 bits of FGL,then the switch will forward multicast > data frame to downstream VL switch. > thanks > weiguo > ------------------------------ > *发件人:* Radia Perlman [radiaperlman@gmail.com] > *发送时间:* 2013年2月1日 4:24 > > *到:* Tissa Senevirathne (tsenevir) > *Cc:* Anoop Ghanwani; Ayan Banerjee; Sam Aldrin; trill@ietf.org; Donald > Eastlake; Jon Hudson > *主题:* Re: [trill] Explaining three options for upgrading to FGL > (fine-grained-labeling) > > Tissa said: > >> how can you make sure all of the so called "Safe FGL" have consistent > behavior > > "Safe FGL" need not all have the *same* behavior as each other...they > just have to do "nothing bad" with an FGL frame. It's worth summarizing > (again) what it means to be "FGL-safe", which allows you to coexist safely > with FGL frames. To be FGL-safe you must do the following: > > a) unicast: you MUST NOT drop a packet because of seeing the unrecognized > FGL tag. You also MUST NOT get confused and do flow hashing improperly > (choosing different paths for packets for the same flow). > > b) multicast pruning: it's OK not to do pruning at all, or to actually > look at all 24 bits of the FGL and prune as a proper FGL guy would do. But > an example of what you canNOT do is look at the first 12 bits of FGL, > pretend it's the same as VL, and delete the multicast packet because nobody > downstream is listening to that 12 bit VL value > > c) egress of either unicast or multicast: you MUST NOT egress an FGL > frame onto a link that is not supposed to get that FGL value > > d) you have to advertise that you are FGL-safe...otherwise other RBs will > assume you are VL ("FGL-unsafe") > > --------- > Also, TIssa said: > >>Do you agree if we say, FGL will always be core of the network, and VL > will be at the edge of the network ? > > With option 2, a VL guy *cannot even be at the edge of a network with FGL > links* unless it is upgraded to FGL-safe AND advertises that it is > FGL-safe. Option 2 says a VL guy is completely ostrasized once FGL-labeled > links are introduced. There is NO coexistence of VL guys and FGL-links. > The only kinds of coexistence in option 2 are: > > a) VL and FGL-safe RBridge, but no actual FGL links yet. > b) FGL-safe guys, even if some of them don't really understand FGL, but > just don't do "anything bad" with it, and FGL frames. > > So...again...the migration phases in option 2 are > 1) VL-only (today's deployment), then > 2) A mixture of VL and FGL-safe, until > 3) EVERYone upgraded to FGL-safe, then > 4) FGL-links can be introduced. > > > ---- > Also, Tissa said: > >>what about some devices who are not "safe FGL" and so on, are we saying > do not buy no safe FGL devices, if you do that you cannot get FGL interop ? > > *If* it's important to have VL guys as transit, and they cannot be > upgraded to FGL-safe because upgrading requires a hardware change (it > involves parsing data packets), then we are stuck with option 3. In option > 3, we can forever have VL guys at the edge speaking through an FGL-safe or > full-FGL core. In option 2, as I said, there is *no coexistence* of VL > guys, *even at the edg*e, once FGL links are introduced. In option 2, a > VL guy, even at the edge, will be ostrasized completely once anyone > advertises connectivity to an FGL link. > > I personally like option 2, because it's simple, but as Einstein said > "make things as simple as possible, but no simpler". We have to make sure > that everyone understands the implications of option 2, and can live with > them. To summarize again (since there seems to be some confusion about > what the implications of option 2 are), > > If we can upgrade all existing VL implementations to FGL-safe through > software upgrade only, then option 2 provides smooth migration by changing > ALL RBridges (edge as well as transit) to FGL-safe, and only after ALL of > them are upgraded, then FGL-labeled links can be introduced. If there are > any remaining VL guys once FGL-labeled links are introduced, the VL guys > are ostrasized, *even if they are just at the edge.* > > If we canNOT upgrade all existing VL to FGL-safe, AND if it's important to > be able to mix VL guys into a network with FGL frames (say, having VL guys > at the edge), then option 3 allows this. > > So hopefully everyone understands the implications of option 2 fully > before voting. As I said, I don't know about whether there are VL chips > that would require a hardware upgrade to become FGL-safe. Assuming there > are none, then I'm quite happy with option 2. And actually, it looks like > people are converging on option 2 (though I hope it's based on fully > understanding option 2). Now is the time for people to speak up, that know > of problems this would cause...for instance, needing to have non-upgradable > VL guys at the edge for a long time. > > Radia > > >
- [trill] Explaining three options for upgrading to… Radia Perlman
- [trill] 答复: Explaining three options for upgradin… Haoweiguo
- Re: [trill] 答复: Explaining three options for upgr… Radia Perlman
- [trill] 答复: 答复: Explaining three options for upgr… Haoweiguo
- Re: [trill] Explaining three options for upgradin… Anoop Ghanwani
- Re: [trill] Explaining three options for upgradin… Donald Eastlake
- Re: [trill] 答复: 答复: Explaining three options for … Donald Eastlake
- Re: [trill] Explaining three options for upgradin… Ayan Banerjee
- Re: [trill] Explaining three options for upgradin… Donald Eastlake
- Re: [trill] Explaining three options for upgradin… Ayan Banerjee
- Re: [trill] Explaining three options for upgradin… Anoop Ghanwani
- Re: [trill] Explaining three options for upgradin… Donald Eastlake
- Re: [trill] Explaining three options for upgradin… Ayan Banerjee
- Re: [trill] Explaining three options for upgradin… Donald Eastlake
- [trill] 答复: 答复: 答复: Explaining three options for … Haoweiguo
- Re: [trill] Explaining three options for upgradin… Yizhou Li
- Re: [trill] Explaining three options for upgradin… Tal Mizrahi
- Re: [trill] Explaining three options for upgradin… hu.fangwei
- Re: [trill] Explaining three options for upgradin… zhai.hongjun
- Re: [trill] Explaining three options for upgradin… Sam Aldrin
- Re: [trill] Explaining three options for upgradin… Linda Dunbar
- Re: [trill] Explaining three options for upgradin… Jon Hudson
- Re: [trill] Explaining three options for upgradin… Sam Aldrin
- Re: [trill] Explaining three options for upgradin… Jon Hudson
- Re: [trill] Explaining three options for upgradin… Sam Aldrin
- Re: [trill] Explaining three options for upgradin… Tissa Senevirathne (tsenevir)
- Re: [trill] Explaining three options for upgradin… Radia Perlman
- Re: [trill] Explaining three options for upgradin… Olen Stokes
- Re: [trill] Explaining three options for upgradin… Radia Perlman
- [trill] 答复: Explaining three options for upgradin… Haoweiguo
- Re: [trill] 答复: Explaining three options for upgr… Radia Perlman
- [trill] 答复: 答复: Explaining three options for upgr… Haoweiguo
- Re: [trill] Explaining three options for upgradin… Jon Hudson