[Nsi-wg] minutes from today's NSI call
Jerry Sobieski
jerry at nordu.net
Thu Apr 21 07:58:00 CDT 2011
Hey John-
On 4/21/11 8:49 AM, John MacAuley wrote:
> The interesting conclusion I came to in this whole discussion is that
> a fully qualified STP is actually an under qualified STP for the layer
> above. The real question we need to ask is if the connection services
> protocol should support the dynamic creation of new topological
> layers, or is it a stitching protocol such that we only interconnect
> already specified topologies. The fully qualified STP leans more
> towards a stitching model, where the under qualified supports the
> creation of new topology layers.
So my key beef with all this is that we have begun discussing topology
as a pre-requisite to getting V1.0 out the dor. And we've added another
feature that was not a requirement. And as you indicate above, there
are other aspects and implications we have not thought through.
None of these objections is about the quality of the concept
proposed...just that its going to take additional thinking to vett it
properly ...additional delay to the 1.0 spec that is unnecessary.
>
> I think both "fully" and "under" have their place in the solution. I
> think the fully-qualified definitely has a place at E-NNI boundaries
> between networks to allow for predetermined (VLAN) connectivity and to
> reduce the need for technology specific negotiation between the
> domains during connection reservation. I can even see that
> administrators may want to use the fully-qualified STP on some client
> ports where limited connectivity options are needed. However, I also
> see great value in the under-specified STP at these client ports as well.
>
> Guy is totally correct in his statement. Everything is solvable
> through the yet to be defined topology protocol ;-)
But we are requiring something in the spec that we have not defined
yet...additional topological constructs.
>
> John.
Jerry
>
> On 2011-04-21, at 6:40 AM, Guy Roberts wrote:
>
>> Hi Jerry,
>> On this point:
>> ‘…I know (and the NSA can tell) what a fully specified STP is because
>> it is in his local name table. But how does an NSA recognize an
>> "underspecified" stp? … ’
>> I don’t see why an under-specified STP can’t be in the topology –
>> after all we have not agreed what the topology looks like. So my
>> feeling is that if a network advertises a 10GE port (under specified
>> STP) then it should still be possible to request a VLAN on that
>> port. This work as follows:
>> RA sends a CS request for a VLAN service, giving one end as an STP
>> for the 10GE port. The PA does its stuff and finds an available VLAN
>> (this is pathfinding so is out of scope for the moment). The PA then
>> sends back a CS confirmation to the RA with the STP of the Ethernet
>> port replaced by the STP of the VLAN.
>> Describing the mechanism of how this is achieved may be too advanced
>> for V1.0, but I don’t think should do anything to the protocol/WSDL
>> to prevent this happening.
>> Guy
>> *From:*Jerry Sobieski [mailto:jerry at nordu.net]
>> *Sent:*21 April 2011 06:26
>> *To:*Guy Roberts
>> *Cc:*nsi-wg at ogf.org <mailto:nsi-wg at ogf.org>
>> *Subject:*Re: [Nsi-wg] minutes from today's NSI call
>> Hi All-
>>
>> I apologize for missing the call today... The Internet2 Spring
>> meeting had me wrapped up, and I just missed the call.
>>
>> I have read the minutes. I have two comments:
>>
>> 1. As much as I want to support the underspecified endpoints
>> thinking, I really don't think we can in V1.0 ... To wit: Define an
>> "underspecified" STP. I know (and the NSA can tell) what a fully
>> specified STP is because it is in his local name table. But how does
>> an NSA recognize an "underspecified" stp? And if the NSA can
>> recognized it, how is it to resolve it into a "fully specified" STP?
>> i.e. what does an "underspecified STP" mean? What are the
>> semantics? Have we just started defining new topology structures?
>>
>> 2. AS for technology specific info in the STP. IMO, we should avoid
>> this religiously - this breaks the NSI abstraction. Why would this
>> even be necessary? The NSI connection service primitives are
>> technology agnostic. Technology specifics may be found in the
>> Service Request that are part of the Service Definition (e.g. MTU),
>> but other than that, we should make sure the primitives themselves
>> remain technology agnostic - including the names of endpoints. The
>> Endpoint will always map to some topological location - *that* is
>> where the physical or technology specific info should be found - not
>> in the stp name itself. Admittedly, we can't stop a local NSA from
>> encoding information in the local endpoint(s) names (e.g.
>> name:="vlan100") but that is purely a local convention and of no
>> significance to the other NSAs. Doing so may have human
>> significance, but not NSI significance. If you encode technology
>> specifics in the WSDL that defines an NSI Message, then you are
>> adding information to the NSI message. That information therefore
>> should be common to all Connection Services regardless of
>> technology. So fundamentally, adding information to the WSDL that
>> defines a NSI message is redefining the NSI message and is therefore
>> considered a protocol addition. As a new protocol addition, it
>> should be justified within the NSI protocol semantics, or should be
>> expressly forbidden. Again - why would this even be necessary?
>>
>>
>> All- If we keep the NSI-CS protocol faithful to the NSI abstractions,
>> (Networks, Endpoints, Connections, and Services) we will be fine. The
>> protocol works beautifully as is without last minute hacks. The CS
>> primitives do Reservations and Provisioning. The issues of
>> pathfinding are dependent on Topology - which we have not worked out
>> yet. Be patient, and have confidence - the CS protocol is really
>> well thought out as is. We will find that many of these issues go
>> away or will be improved with the ensuing topology
>> discussions...don't panic and try to wedge something in at this
>> eleventh hour that we have not considered thoroughly.
>>
>> Thanks!
>> Jerry
>>
>> On 4/20/11 1:36 PM, Guy Roberts wrote:
>> The minutes from today’s NSI call are available here:
>> http://forge.gridforum.org/sf/go/doc16256?nav=1
>> _____________________________________________________________________
>> ** Guy Roberts, PhD Network Engineering & Planning
>> * * Tel: +44 (0)1223 371300
>> * * City House Direct: +44 (0)1223 371316
>> * 126-130 Hills Road Fax: +44 (0)1223 371371
>> * Cambridge
>> * CB2 1PQ E-mail:guy.roberts at dante.net
>> <mailto:guy.roberts at dante.org.uk>
>> D A N T E United Kingdom WWW: http://www.dante.net
>> _____________________________________________________________________
>>
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