[Nsi-wg] NSI endpoint references

Sat Mar 12 20:03:38 CST 2011

Yes I think there might be some "crosstalk" here.

I think Jerry is talking about STPs and Vangelis may be talking about NSA EPR?

Regarding STPs, since there is amapping of STP to a data plane topological space, whether multiple NSA's advertise same end-point is upto the implementation of the domain and its policy. We had agreed a while ago that ONE NRM "owns" the provisioning and resource allocation of that end-point.

btw, someone keeping track of how many things are out of scope of NSI? :)

Inder

On Mar 12, 2011, at 5:49 PM, John MacAuley wrote:

> Oops, forgot to make both components mandatory as Vangelis has.  I guess I should have moved back in time :-)
> 
> Are we defining an STP or an endpoint?  Are they the same and we are just changing terminology?  I am a bit confused.
> 
>> - Does a domain-id represent ownership/responsibility of the EPR by an  
>> NSA?
>> - Can an EPR "belong to" multiple NSAs?
> 
> I think we are saying an endpoint belongs to a single domain, but I believe multiple NSA could manage the same domain, and therefore, the same endpoint.
> 
>> - Does this affect which NSAs receive a connection request? If so, how?
> 
> Domain to NSA resolution is out of scope based on the last NSI call.
> 
> John.
> 
> 
> On 2011-03-10, at 4:19 PM, Evangelos Chaniotakis wrote:
> 
>> Jerry,
>> 
>> I disagree with part of what you're saying here: i.e. that the entire  
>> endpoint reference is a string. In my opinion the standard should  
>> define it is an abstract tuple: (domain-id, local-id).
>> 
>> The implementation of the standard should decide how to encode that  
>> tuple. It could be a pair of two XML elements for SOAP, or a colon- 
>> delimited concatenation, or whatever. It's absolutely trivial to go  
>> the extra mile and support multiple representations, converting  
>> between them on the fly.
>> 
>> Let me propose this schema snippet for the SOAP implementation:
>> 
>> <xsd:complexType name="nsiEndpointReference">
>>  <xsd:sequence>
>>    <xsd:element name="domainId" type="xsd:string" maxOccurs="1"  
>> minOccurs="1"/>
>>    <xsd:element name="localId" type="xsd:string" maxOccurs="1"  
>> minOccurs="1"/>
>>  </xsd:sequence>
>> </xsd:complexType>
>> 
>> 
>> I do agree with the points you're making about the local part, and I'm  
>> fine with the clarification you want to explicitly set in the standard.
>> 
>> 
>> 
>> In my opinion a much more important clarification needs to be made  
>> about the domain-id part. Here are some questions that should probably  
>> be answered.
>> 
>> - Does a domain-id represent ownership/responsibility of the EPR by an  
>> NSA?
>> - Can an EPR "belong to" multiple NSAs?
>> - Does this affect which NSAs receive a connection request? If so, how?
>> 
>> 
>> 
>> On Mar 10, 2011, at 12:03 PM, Jerry Sobieski wrote:
>> 
>>> Hi Vangelis-
>>> 
>>> You are right except for one part:...  As I see this, it is really  
>>> only the NRM that cares about the endpoint name.  NSI has no  
>>> interest in what the endpoint string looks like other than maybe  
>>> some purely aesthetic lexical conventions (e.g. no backspace  
>>> characters, etc.)    Therefore, the *NSI* protocol implementers must  
>>> explicitly treat the string as just a string.    If one domain wants  
>>> to name its endpoints with topology info encoded, they can do that,  
>>> but no other domain or NSA will look for that info in their  
>>> string...as far as the other NSAs are concerned, the string is just  
>>> a string.
>>> 
>>> I will say though that for the mapping of the NSI endpoint reference  
>>> to the NRM resource *is* the responsibility of the implementors who  
>>> are coding the PA frontend onto an NRM.  They do need to know if  
>>> local convention expects or requires local endpoints to be named a  
>>> certain way.  But again it is only relevant for the local endpoints,  
>>> and so is only of local significance and only for that particular  
>>> NRM.   So this is not an NSI issue.
>>> 
>>> I recommend that we are explicit in the NSI standard and say the  
>>> following:
>>> The <local part> of the endpoint reference is a string that uniquely  
>>> identifies a particular endpoint within the <domain> specified.    
>>> The NSI framework and protocol explicitly leave the value of the  
>>> endpoint reference string to be assigned by the network domain  
>>> within which the endpoint resides.   The NSI Framework and protocol  
>>> do not encode any information directly into the endpoint reference  
>>> string.
>>> 
>>> How is that?   This insures that local domains have full sway to  
>>> name their own endpoints as they see fit.
>>> 
>>> Best regards
>>> Jerry
>>> 
>>> 
>>> On 3/10/11 11:48 AM, Evangelos Chaniotakis wrote:
>>>> Jerry,
>>>> 
>>>> If I may distill your email to:
>>>> 
>>>> "Let's define an NSI-CS endpoint reference as this tuple: (globally  
>>>> unique domain identifier, locally scoped opaque identifier)."
>>>> 
>>>> I'm fine with that definition.
>>>> 
>>>> The actual implementation/representation/format of such a tuple  
>>>> should be left to the implementors of the protocol. It's just an  
>>>> ordered pair of strings, it does not deserve a big discussion about  
>>>> formats.
>>>> 
>> 
>> -- 
>> Evangelos Chaniotakis
>> Network Engineer, ESnet
>> Visit our blog: http://bit.ly/9mNapV
>> 
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> 
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---
Inder Monga
imonga at es.net