Re: [sfc] 答复: questions of "load balancing considerations" in the draft-quinn-sfc-arch-05

["Andrew G. Malis" <[e-mail]>]

Joel,

I disagree, I really don't see it as confusing at all. We're all in
agreement that there will be cases where a service function is split among
multiple hardware and/or software entities that can work in parallel, or
else there wouldn't be a section on load sharing. How else would one
describe these entities if not as "Service Function Instances"?

Cheers,
Andy

On Thu, May 29, 2014 at 3:57 PM, Joel M. Halpern <[e-mail]>wrote:

> the problem I have with the definition you propose for Service Function
> Instance is that what is an instance will depend upon where you look.
> What management, and particularly what virtual machine monitoring and
> management, sees as an instance has to be a single image running on a
> single VM.
> But what Service Chaining sees as an instance may be one such thing, or
> may be a cluster of such things organized in such a way as to present a
> single view to the service chaining infrastructure.
>
> Thus, trying to define Service Function Instance, and then talk explicitly
> about such instances in service chaining, gets very difficult.  We are
> likely to end up with a definition that says that a service function
> instance may be made up of multiple software instances.  Such a definition
> seems likely to cause more confusion than it solves.
>
> If we can come up with a definition that allows for the range of
> deployments, and does not itself further confuse the readers, then I am
> happy to add such a term definition and usage in the document.
>
> Yours,
> Joel
>
>
> On 5/29/14, 2:25 PM, Linda Dunbar wrote:
>
>> It would be so much easier to formally introduce the concept of
>> "Service Function Instance" in SFC. For example:
>>
>> "Service Function Instance: One instantiation of a service function.
>> One service function could have multiple identical instances.
>>
>> For a service function with different functional instantiations, e.g.
>> one instantiation applies policy-set-A (NAT44-A) and other applies
>> policy-set-B (NAT44-B), they are considered as two different service
>> functions."
>>
>> Some Service Function Instances are visible to Service Chain Path.
>> Sometimes a collection of service function instances can appear as
>> one single entity to the Service Chain Path."
>>
>>
>> Linda
>>
>>