Re: [trill] draft-mme-trill-fcoe as an independent submission

"Pat Thaler" <> Fri, 19 October 2012 23:59 UTC

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From: "Pat Thaler" <>
To: "Jon Hudson" <>, "" <>
Thread-Topic: [trill] draft-mme-trill-fcoe as an independent submission
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Date: Fri, 19 Oct 2012 23:59:03 +0000
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Cc: Donald Eastlake <>, Anoop Ghanwani <>
Subject: Re: [trill] draft-mme-trill-fcoe as an independent submission
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The draft seems to have only partly implemented the comments from INCITS T11. 

Terminology usage that is inconsistent with FC-BB-5 FCoE definitions. As defined in FC-BB-5, the FCF includes any Ethernet Switching Elements that are packaged with the FC Switching Element. FCoE. Therefore, the box labeled FCF in Figure 2 is not an FCF, it is an FC Switching Element plus its underlying FC layer 2 virtual ports and FCoE link end points. The FCF in that picture is the whole FCRB.

There seems to have been some attempt at a change to respond to the comment on Figures 4 and 5 but it still implies that hop by hop forwarding from FCF to FCF is likely. In fact, each FCF will attempt to initiate Inter-Switch Links (ISLs) with each FCF that it sees. Therefore, there will be an ISL between ToR 1 and ToR 2 unless there are some management constraints applied such that ToR 1 only sees EoR and can not send directly to ToR 2. Therefore, the more likely forwarding for the packet described in is that the FCF in ToR 1 addresses the packet to the FCF in ToR 2 and the packet flows through the RBridge in the EoR but not through the FCF in EoR. Similarly in, the likely FCF path is from ToR to Core bypassing the FCF in the EoR. Given the choice of 2 hops or 1 hop (from the Fibre Channel view of hops), FSPF is generally going to choose 1 hop. 

It is theoretically possible to put in constraints so that the extra FCF hop is taken, but it isn't clear that there is any reason to do so and the draft doesn't describe doing that so in describing the path, the draft should describe the more likely path.

The words in the last paragraph of 3.1 were rearranged, but it still says about the same thing.  The comment that the paragraph should be toned down hasn't been addressed by that change. 

Even as an individual draft, the corrections should be made, especially terminology consistency and describing the more likely path for a packet.


-----Original Message-----
From: Jon Hudson [] 
Sent: Thursday, October 18, 2012 10:11 PM
Cc: Donald Eastlake; Anoop Ghanwani
Subject: Re: [trill] draft-mme-trill-fcoe as an independent submission

I agree.

I reviewed this draft.

It has no material impact and requires no changes in or by the TRILL or FCoE standards.

We have _plenty_ todo in TRILL and really need to stay focused.

And while this is by no means meant to insult the authors, this is a harmless informational draft that stands on its own as it is. 

I do not support making this a WG group document. 

It should be simply published as an individual submission.


On Oct 18, 2012, at 4:56 PM, Anoop Ghanwani <> wrote:

> While I don't see any value in having this as a
> working group document, I don't have any objections
> to have it published as an individual submission.
> Anoop
> On Wed, Oct 17, 2012 at 8:23 PM, Donald Eastlake <> wrote:
>> Hi,
>> was briefly
>> presented to the TRILL WG at the Quebec City IETF-81 meeting. I'll
>> paste an extract from the minutes at the end of this email.
>> There have been three references to this draft on the TRILL WG mailing
>> list (before this message), none of which produced any response:
>> The draft is being processed by the RFC Independent Submissions Editor
>> and is awaiting a determination by the IESG as to whether the draft
>> does or does not conflict with ongoing work in the IETF such as that
>> of the TRILL WG. Based on the current state of the IESG ballt
>> (,
>> I request further WG discussion of whether or not this draft should be
>> a TRILL WG draft and whether or not it conflicts with work in the
>> Thanks,
>> Donald
>> =============================
>> Donald E. Eastlake 3rd   +1-508-333-2270 (cell)
>> 155 Beaver Street, Milford, MA 01757 USA
>> Extract from Minutes of TRILL WG at IETF-81:
>> FCoE over TRILL, David Melman (Marvell), Tal Mizrahi (Marvell)
>> draft-mme-trill-fcoe-00.txt
>> (very limited time because earlier presentations and discussion ran
>> over)
>> Tal Mizrahi (Marvell): This draft is intended for
>> informational. ... selected slides ...
>> Anoop Ghanwani: Are you changing the TRILL header hop-by-hop.
>> Donald: The frame is being TRILL encapsulated and decapsulated at each
>> hop.
>> Anoop: So the TRILL Header isn't doing anything. The whole path is
>> computed by FCSP. If you are running both control planes, why have the
>> TRILL Header at all.
>> Tal: There is a slide on that: not all RBridges are FCRBs. In that
>> case, you still want the TRILL clouds to do optimal routing.
>> Puneet Agarwal (Broadcom): I don't see what this does other than state
>> the obvious. FCoE is running over TRILL. Why do you need a draft for
>> that?
>> Tal: We are just showing how they work together.
>> Puneet: So, should I do a draft on IP routing over TRILL?
>> Donald: It is a little different because you would normally have the
>> routers at the edge but here you have the Fiber Channel devices
>> distributed throughout the TRILL cloud with a savings in cabling and
>> cabinetry. If the FC is external to the TRILL cloud, then typically
>> you have to transit the TRILL cloud twice. So, it is a way of doing
>> it. If you think this draft has no value, so be it. If the WG thinks
>> that way, then it shouldn't be a working group draft.
>> Puneet: OK. I don't think it should be a working group draft.
>> Donald: Well, we are out of time. Thanks everyone and see you in
>> Taiwan.
>> _______________________________________________
>> trill mailing list
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