Re: [vnfpool] 答复: 答复: 答复: Updated VNFPool Charter

[LAC Chidung <[e-mail]>]

Hi Ning,
1- On further consideration, my remark (i) in the previous e-mail ("/no 
redundancy at all ...../") should not be applied in the VNF context if 
the intention is to use a pool for redundancy purposes *while minimizing 
the needed resources*. As shown in the figure enclosed, this PNF scheme 
(no redundancy at all, i.e., all instances of the pool participate 
actively) is not applicable in the VNF framework where additional 
instances are created *only* if needed.
2- Back to your e-mail of June 19th "/the VNF instance scaling within a 
VNF pool is included in the charter/": I don't think "scaling", 
"scalability" appearing in the charter - it would be nice to introduce a 
sentence (somewhere) with one of these two words to avoid this 
ambiguity. Again, scaling in/out is one main characteristic of VNF.
Best,
Chidung

Le 27/06/2014 03:36, Zongning a écrit :
>
> Hi, Chidung,
> Thanks for your suggestions. I will make the text clear for comment 
> Z2. But for comment Z9, I’d prefer to keep “VNF Pool”, as we don’t 
> propose/discuss a concrete VNF Pool architecture in the charter, but 
> just introduce a general concept.
> Look forward to your further comments.
> -Ning
>
> *发 件人:*LAC Chidung [mailto:[e-mail]]
> *发 送时间:*2014年6月26日22:53
> *收件人:*Zongning
> *抄送:*[e-mail]
> *主题:*Re: 答复: [vnfpool] 答复: Updated VNFPool Charter
>
> Hi Ning,
> Thank you for the reply. Some comments/suggestions to your:
> * comment Z2: I knew that the « elementary » NFs are part of the job, 
> but wanted to suggest to add something in this section to avoid 
> readers to perceive  the wrong feeling mentioned in my comment #1
> * comment Z7: Thank you for this clarification. I thus understand that 
> three types of pools (and not more than three) may exist:
>      - (i) no redundancy at all, i.e., all instances of the pool 
> participate actively - an upstream load balancing mechanism shares the 
> incoming load among these instances;
>      - (ii) 1:1 (active-active) redundancy - for example, 5 "images" 
> (to avoid the word 'instance') of the VNF, and each of them is 
> redundant -> in this case, there are 10 instances running in parallel 
> in the pool;
>      - (iii) N+K (active-standby) redundancy where some instances run 
> actively, while others are in a dormant state.
>
> * comment Z9: How about this add-on then ? "... achieved by the VNF 
> Pool *architecture* utilized/adopted by the VNF ..."
> Best,
> Chidung
>
> Le 19/06/2014 05:14, Zongning a écrit :
>
>     Hi, Chidung,
>     Please see my reply enclosed in the attachment. Regarding
>     comment#6, I’d like to explain that we don’t restrict to the case
>     that in a pool, at a given time, there is only one running
>     instance and all others are sleeping. A pool should be flexible to
>     handle more cases, including multiple running instances and
>     multiple standby instances.
>     Look forward to your further comments & suggestions.
>     -Ning
>
>     *发 件人:*LAC Chidung [mailto:[e-mail]]
>     *发 送时间:* 2014年6月19日 0:40
>     *收件人:* Zongning
>     *抄送:* [e-mail] <mailto:[e-mail]>
>     *主题:* Re: [vnfpool] 答复: Updated VNFPool Charter
>
>     Hi Ning,
>     1) Is it exact that scaling out/in, one main characteristic of
>     VNFs (compared to PNFs), is not included ?
>     2) Some comments/suggestions are enclosed.
>     Best,
>     Chidung
>
>     Le 12/06/2014 05:38, Zongning a écrit :
>
>         Dear all,
>         Please review the charter text included in the last email. We
>         are hoping that a general consensus on the charter could be
>         achieved on the list, then a stable charter is ready for the
>         VNFPool session in Toronto.
>         Thanks.
>         -Ning
>
>         *发件人:*vnfpool [mailto:[e-mail]] *代 表
>         *Zongning
>         *发 送时间:* 2014年6月12日 11:20
>         *收件人:* [e-mail] <mailto:[e-mail]>
>         *主题:* [vnfpool] Updated VNFPool Charter
>
>         Dear all,
>
>         Based on the list discussion since we posted the last version,
>         I have made some (minor) revision of the charter. The main
>         changes are:
>
>         1)State that service state synchronization is out of scope “in
>         this phase”;
>
>         2)Include VNF Pool with both virtualized and non-virtualized
>         network function for further study;
>
>         3)Explicitly state that the reference solution & gap analysis
>         is not limited to RSerPool, but open to any other solutions,
>         although no decision on protocols will be made in this phase;
>
>         4)State that the linkage between SFC and VNF Pool is just like
>         a pool user and a pool – nothing specified (yet);
>
>         5)Update bullet #4 under “Questions that are raised…”, to keep
>         it consistent with the idea that pooling is not visible to the
>         service control entity.
>
>         ==========================================================================
>
>         Network functions such as firewalls, load balancers, and WAN
>         optimizers are conventionally deployed as specialized hardware
>         servers in both network operators' networks and data center
>         networks as the building blocks of the network services. There
>         is a trend to implement such network functions as software
>         instances running on general purpose servers, via a
>         virtualization layer (i.e., hypervisors). These virtualized
>         functions are called Virtualized Network Functions (VNFs),
>         which can be used to build network services.
>
>         The use of VNFs introduces additional challenges to the
>         reliability of the provided network services. A single VNF
>         instance would typically not have built-in reliability
>         mechanisms on its host (i.e., a general purpose server).
>         Instead, there are more factors of risk such as software
>         failure at various levels including hypervisors and virtual
>         machines, hardware failure, and instance migration that can
>         make a VNF instance unreliable.
>
>         In order to achieve higher reliability, a VNF may adopt a
>         pooling mechanism, where a number of VNF instances with the
>         same function can be grouped as a pool to provide the
>         function. We call such a pool a VNF Pool.Conceptually, a Pool
>         Manager is used to manage a VNF Pool, e.g., selects
>         active/standby VNF instances, and potentially interacts with a
>         service control entity. Such a service control entity is an
>         entity that orchestrates a set of network functions to build
>         network services. The major benefit of using VNF Pool is that
>         reliability mechanisms such as redundancy model are achieved
>         by the VNF Pool inside the VNF and thus not visible to the
>         service control entity. A VNF Pool-enabled VNF still appears
>         as a normal VNF when orchestrated by a service control entity.
>
>         Questions that are raised by the addition of a pooling
>         mechanism to VNF include:
>
>         ·How to manage the redundancy model, e.g., select
>         active/standby VNF instances in a VNF Pool?
>
>         ·What pool states need to be maintained to support the pooling
>         mechanism itself, and how are such states maintained?
>
>         ·What information is exchanged between a VNF and a service
>         control entity? For example, how can a VNF Pool be addressed
>         by the service control entity?
>
>         ·After a VNF instance failover, how does the Pool Manager
>         notify the service control entity some characteristic changes
>         of the VNF, e.g., capacity change, but without disclosure of
>         the pooling procedure?
>
>         The WG initially focuses on several reliability mechanisms
>         that are mainly associated with a redundancy model based on a
>         VNF Pool. Additional mechanisms may include pool state
>         maintenance only for pooling purpose. Service state
>         synchronization is out of scope for this phase. The
>         WGassumesthat a VNF Pool contains redundant VNF instances of
>         same functional type. Different types of VNFs are envisioned
>         to be held in separate VNF Pools. VNF Pool composed by both
>         virtualized and non-virtualized functional instances may be
>         included after further use case and requirements study. The WG
>         will address the reliability of an individual VNF, but not the
>         reliability related to the control or the routing between
>         adjacent VNFs that can form a network service.
>
>         Specifically, the WG will work on the following technical aspects:
>
>         ·Redundancy management within a VNF Pool, such as the
>         signaling between the Pool Manager and the instances in the
>         pool for instance registration, backup instances selection,
>         and switching between active and standby instances.
>
>         ·The protocol between the Pool Manager and the underlying
>         network to collect the network information required for
>         appropriate placement/selection of backup instances.
>
>         ·The protocol between a VNF and the service control entity to
>         exchange operational information between a VNF Pooland the
>         service control entity.
>
>         ·Identify and analyze reliable interfaces, such as transport
>         protocol like MPTCP and SCTP for reliable delivery of the
>         messages associated with the redundancy management within a
>         VNF Pool.
>
>         ·Analysis of pooling security characteristics and requirements
>         to identify and mitigate threats against the pooling
>         mechanism. Identification of an appropriate trust model
>         between pool members, and between pool members and the Pool
>         Manager.
>
>         The WG plans to deliver a problem statement, a set of use
>         cases, requirements and an architecture covering the
>         aforementioned technical aspects, and applicability and gap
>         analysis of existing technologies including but not limited to
>         RSerPool. We will rely heavily on existing IETF technologies,
>         but that gaps will be found around problems like redundancy
>         mechanisms, state maintenancesolely for pooling purposes,
>         reliable transport, and trust/security, all of which will need
>         to be considered and addressed. Although no decision on
>         protocols will be made in this phase, we will keep open for
>         candidate protocols for VNF Pool. The WG will seek
>         re-chartering before adopting any work to develop new, or
>         extend existing, protocols.
>
>         In particular, we will work closely with the SFC WG, as we
>         believe that SFC and VNF Pool are independent but
>         complementary. SFC would essentially see a VNF Pool-enabled
>         VNF as a normal service function and therefore be able to
>         merge it into an SFC just like any other service functions.
>         Just like the communication between any pool users and VNF
>         Pool, the information exchanged between the VNF Pool and the
>         SFC may include some operational information of the VNF Pool.
>
>         Goals and Milestones:
>
>         December 2014 - Submit VNFPool Problem Statement to IESG for
>         publication as an Informational document.
>
>         April 2015 - Submit VNFPool Use Cases to IESG for publication
>         as an Informational document.
>
>         August 2015 - Submit VNFPool Requirements, including the
>         manageability of VNF Pool to IESG for publication as an
>         Informational document.
>
>         August 2015 - Submit VNFPool Architecture to IESG for
>         publication as an Informational document.
>
>         December 2015 - Submit one or more Applicability and Gap
>         Analysis of existing protocols to VNFPool to IESG for
>         publication as Informational document(s).
>
>         ==========================================================================
>
>         Your comments and suggestions to the charter are ALWAYS highly
>         appreciated!
>
>         Thanks.
>
>         -Ning
>
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