Re: [vnrg] Review of draft-shin-virtualization-meta-arch-01.txt

[Didier Colle <[e-mail]>]

Dear Martin, all,

My two cents in this discussion.

Martin Stiemerling wrote:
> [writing as individual RG member and not as chair]
>
> Dear all,
>
> Here is a brief review of draft-shin-virtualization-meta-arch-01.txt.
>
> - Section 1, 1st paragraph: this describes abstraction but not virtualization.
>   

Would you then say that abstraction is a key tool to realizing 
virtualization?
And what would then be definition of "virtualization"? E.g., creating 
"virtual things/instances"? To my feeling, "virtualization" means 
creating "virtual things" by "abstracting away the real things 
(infrastructure)".
Hmm... this might become a pretty "artificial" discussion...

Although I tend to agree with the text that virtualization bottom-line 
always boils down to abstraction of the physical infrastructure, I 
disagree with the statement in the text: "... or end users can interact 
with those resources WITHOUT THE KNOWLEDGE OF THE PHYSICAL CHARACTERISTICS."
* For example, in an IP/WDM scenario the overlaid IP network(s) is(/are) 
virtual networks but still the IP routing protocols running in 
this(/these) virtual IP networks needs to be aware of possible SRLGs. 
Thus "without knowledge" does not seem correct to me, "with limited 
ABSTRACTED knowledge" seems more appropriate to me.
* Is this compliant with the statement in section 1.1 "When combined 
with programmability feature in network elements, USERS of virtual 
networks CAN PROGRAM the network elements on any layers FROM PHYSICAL 
LAYER to application layer according to users' requirements." How do you 
program the physical layer WITHOUT KNOWING ANYTHING about that physical 
layer?

> - Section 1, page 3, bullet list: how does this related to VNs?
> - Section 1.1: too narrow for VN and it mixes VNs with programmable networks.
>   

Euh... well, to me programmability is a key requirement for virtual 
networks. Perhaps programmability should not be mixed in section 1.1, 
but to my understanding it is missing from the requirements section 3.

> - Section 2: First para: de-ossification may be one motivation but is in IMHO not the motiviation. 
> - Section 2: VNs are not necessarily programmable networks. 
>   

Again I would not exclude programmability from the requirements.
When having a Software-Defined Radio infrastructure, it should be 
possible to create SDR virtual network instances.
When having an infrastructure based on NetFPGA-alike hardware, it should 
be possible to create FPGA-programmable virtual network instances (e.g., 
part of the FPGA footprint).

> - Section 3: The requirements are too high-level. It would be good to get more detailed requirements and where (from what system) these requirements are.
>   

Some thoughts:
* A system managing the virtual instances is needed.
* The infrastructure should provide a standardized interface/api to such 
system.
* An interface between that mgmt system and the user: giving user 
ABSTRACTED info on capabilities of the infrastructure over which he 
wants to create a virtual instance (e.g., is it programmable, or do you 
have only a limited number of combinations of "lego bricks"?) 
Information on the config/mgmt interface of the virtual network 
(element) instance(s), ... information on the subset of resources that 
were assigned to a virtual network instance (e.g., a virtual network 
instance might have been assigned a certain set of VLAN-IDs that he only 
he can use)
* Enforcement of isolation
* Enforcement of performance guarantees

Kind regards,

Didier

> - Section 4: It's too high-level. A good use case would describe a VN use case and the resulting challenges and requirements
>
> I personally do not yet see this document to be the RG problem statement draft at this point of time. 
>
> The draft misses some important points:
> - what are some use cases you have in mind (system and what it does)
>   - e.g., testbed virtualization, operator-scale, Internet-scale, etc?
> - what components are you using
> - how do these components interact
> - what about the existing work, e.g., VPNs, L2 link bundling technologies, virtual routers
> - what are the problems?
>
> In general: I do not yet see that this draft is really a problem statement. It makes a start and its worth keep working on it, but needs more thoughts and discussions.
>
>   Martin
>
>
> [e-mail]
>
> NEC Laboratories Europe - Network Research Division
> NEC Europe Limited | Registered Office: NEC House, 1 Victoria Road, London W3 6BL | Registered in England 2832014 
>
>
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-- 
Didier Colle
Ghent University - IMEC - IBBT
Department of Information Technology (INTEC)
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