Re: [Teas] Network Slicing design team definitions - isolation and resolution

"Joel M. Halpern" <jmh@joelhalpern.com> Thu, 30 April 2020 03:22 UTC

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To: Greg Mirsky <gregimirsky@gmail.com>
Cc: "teas@ietf.org" <teas@ietf.org>
References: <E0C26CAA2504C84093A49B2CAC3261A43F83079E@dggeml531-mbs.china.huawei.com> <c467e349-efd8-1519-7d8a-1f242042cfed@joelhalpern.com> <a94fe17dae2244b0af6a9303e68f1e0e@huawei.com> <b54e1be6-cfd2-0bf7-1601-f6764253dfa3@joelhalpern.com> <CA+RyBmWaBN=WP3A4qwCOvm5Vax2ookYYas1-L5yQFiGmRH2OBA@mail.gmail.com> <aac854e6-92e5-59ea-3dac-e95fbf424a98@joelhalpern.com> <fc242b850689461da7861d81e3ab1a13@huawei.com> <CA+RyBmXrqjXNtFiYyoUT5ACtJ8fOJF7z78xnjC1MosNxXTZYzw@mail.gmail.com> <1212271585.1682731.1588096301849@mail.yahoo.com> <CA+RyBmU=cvnthYwP8JFOw1yLScb5c+M986dGjib=Y9ie9LQiJQ@mail.gmail.com>
From: "Joel M. Halpern" <jmh@joelhalpern.com>
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Subject: Re: [Teas] Network Slicing design team definitions - isolation and resolution
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I have never seen a good or useful distinction between hard and soft 
isolation.  The one described in the draft (based on causes of failure) 
is not effective.

Everything has a confidence / reliability / variability.  some are 
better than 5 9s.  And some are one 9.  Niether is hard.  And neither is 
soft.

Yours,
Joel

On 4/29/2020 11:13 PM, Greg Mirsky wrote:
> Hi Igor,
> I agree with you but with some clarification. If we, as in the draft, 
> introduce the notion of "hard isolation" and "soft isolation", then, in 
> my opinion, we acknowledge that in some cases isolation is not 
> guaranteed. Hence, everything that you've said is the case for hard 
> isolation. But for soft isolation, I think, a network might be affected 
> by another network.
> What is your opinion on hard vs. soft isolation?
> 
> Regards,
> Greg
> 
> On Tue, Apr 28, 2020 at 10:52 AM Igor Bryskin <i_bryskin@yahoo.com 
> <mailto:i_bryskin@yahoo.com>> wrote:
> 
>     Hi Greg,
> 
>     Flow isolation and network isolation are different things. For
>     example, you do not expect receiving data in one network broadcasted
>     over properly isolated another network. Likewise, you do not expect
>     congestion in one network caused by an activity in another
>     (isolated) network. Om the other hand, flows in the same network may
>     influence on each other.
> 
>     Igor
> 
> 
>     On Tuesday, April 28, 2020, 12:30:38 PM EDT, Greg Mirsky
>     <gregimirsky@gmail.com <mailto:gregimirsky@gmail.com>> wrote:
> 
> 
>     Hi Jie,
>     thank you for listing the existing cases of isolation term use in
>     IETF RFCs. My understanding of these quotes is that most of them
>     refer to data flow isolation/separation. And that is what
>     Connectivity Verification OAM is intended to monitor. At the same
>     time, as Joel has pointed out, the term isolation is being used in
>     the draft-nsdt-teas-transport-slice-definition in a different
>     manner, particularly in Section 4.1.1. In that section, several
>     levels (hard and soft) of the isolation are discussed whereas
>     isolation of data flows, in my understanding, is always "hard". As
>     I've mentioned earlier, we might look for different terms when
>     referring to use/access to underlay resources vs. data flows
>     interaction.
> 
>     Regards,
>     Greg
> 
> 
>     On Tue, Apr 28, 2020 at 2:31 AM Dongjie (Jimmy) <jie.dong@huawei.com
>     <mailto:jie.dong@huawei.com>> wrote:
> 
>         Hi Joel and Greg,
> 
>         As I mentioned during the virtual meeting, isolation was
>         described as a requirement in several PPVPN requirement and
>         framework RFCs. In summary, isolation is firstly required to
>         avoid unwanted exposure of both data traffic and routing
>         information, then it is also mentioned that isolation is needed
>         to avoid the effects of traffic congestion happened in other
>         VPNs in the network.
> 
>         Just quote some of them:
> 
>         RFC 3809: Generic Requirements for Provider Provisioned Virtual
>         Private Networks (PPVPN)
> 
>         4.4.  Data isolation
> 
>             The PPVPN MUST support forwarding plane isolation.  The
>         network MUST
>             never deliver user data across VPN boundaries unless the two
>         VPNs
>             participate in an intranet or extranet.
> 
>             Furthermore, if the provider network receives signaling or
>         routing
>             information from one VPN, it MUST NOT reveal that information to
>             another VPN unless the two VPNs participate in an intranet or
>             extranet.
> 
> 
>         RFC 4031: Service Requirements for Layer 3 Provider Provisioned
>         Virtual Private Networks (PPVPNs)
> 
>         4.1.  Isolated Exchange of Data and Routing Information
> 
>             A mechanism must be provided for isolating the distribution of
>             reachability information to only those sites associated with
>         a VPN.
>             ...
>             Note that isolation of forwarded data or exchange of
>         reachability
>             information to only those sites that are part of a VPN may
>         be viewed
>             as a form of security - for example, [Y.1311.1], [MPLSSEC].
> 
>         5.8.  Isolation
> 
>             These features include traffic and routing information exchange
>             isolation, similar to that obtained in VPNs based on Layer 1 and
>             Layer 2 (e.g., private lines, FR, or ATM) [MPLSSEC].
> 
>         6.8.  Isolation of Traffic and Routing
>             ...
>             From a high-level SP perspective, a PE-based L3VPN MUST
>         isolate the
>             exchange of traffic and routing information to only those
>         sites that
>             are authenticated and authorized members of a VPN.
> 
>             In a CE-based VPN, the tunnels that connect the sites
>         effectively
>             meet this isolation requirement if both traffic and routing
>             information flow over the tunnels.
> 
>             An L3VPN solution SHOULD provide a means to meet L3VPN QoS SLA
>             requirements that isolates VPN traffic from the effects of
>         traffic
>             offered by non-VPN customers.  Also, L3VPN solutions SHOULD
>         provide a
>             means to isolate the effects that traffic congestion produced by
>             sites as part of one VPN can have on another VPN.
> 
> 
>         RFC 4110: A Framework for Layer 3 Provider-Provisioned Virtual
>         Private Networks (PPVPNs)
> 
>         1.2 Overview of Virtual Private Networks
> 
>             In PE-based layer 3 VPNs, the PE devices may
>             route the VPN traffic based on the customer addresses found
>         in the IP
>             headers; this implies that the PE devices need to maintain a
>         level of
>             isolation between the packets from different customer networks..
>             ...
>             Tunneling is also important for other reasons, such as providing
>             isolation between different customer networks, allowing a
>         wide range
>             of protocols to be carried over an SP network, etc. 
>         Different QoS
>             and security characteristics may be associated with different
>             tunnels.
> 
>         4. 3 VPN Tunneling
> 
>             Another capability optionally provided by tunneling is that of
>             isolation between different VPN traffic flows.  The QoS and
>         security
>             requirements for these traffic flows may differ, and can be
>         met by
>             using different tunnels with the appropriate
>         characteristics.  This
>             allows a provider to offer different service characteristics for
>             traffic in different VPNs, or to subsets of traffic flows
>         within a
>             single VPN.
> 
> 
>         Hope this helps.
> 
>         Best regards,
>         Jie
> 
>          > -----Original Message-----
>          > From: Teas [mailto:teas-bounces@ietf.org
>         <mailto:teas-bounces@ietf.org>] On Behalf Of Joel M. Halpern
>          > Sent: Tuesday, April 28, 2020 5:33 AM
>          > To: Greg Mirsky <gregimirsky@gmail.com
>         <mailto:gregimirsky@gmail.com>>
>          > Cc: teas@ietf.org <mailto:teas@ietf.org>
>          > Subject: Re: [Teas] Network Slicing design team definitions -
>         isolation and
>          > resolution
>          >
>          > Greg, that definition seems to be a specific subset of VPN.
>          > As far as I can tell, the slice definition does include what
>         endpoints the slice
>          > participants can talk to.  Presumably, with some way to say
>         "the Internet".
>          > So Whether the slice supports communication with the Internet
>         or not is
>          > definitely an observable property.  I would tend not to call
>         it isolation.
>          > Separately, the definition you propose is unrelated to the
>         definition in the
>          > document, Which is why I suggest, for now, removing all
>         discussion of
>          > isolation from the document.
>          >
>          > Yours,
>          > Joel
>          >
>          > On 4/27/2020 5:22 PM, Greg Mirsky wrote:
>          > > Dear Joel,
>          > > thank you for bringing the matter of "isolation" to the
>         discussion. I
>          > > agree, that it is not practical to expect physical
>         isolation in modern
>          > > networks. In my view, a transport slice that requires
>         isolation is as
>          > > a transport connection that expects to receive data only
>         from the
>          > > specific domain and not from any other domain. In other
>         words, I view
>          > > isolation as the absence of mis-connectivity (in transport
>         network
>          > > interpretation which differentiates between path continuity
>         check and
>          > > connectivity verification). If my interpretation is
>         acceptable, then
>          > > isolation can be monitored using connectivity verification OAM
>          > mechanism(s).
>          > > I much appreciate your thoughts, opinion on the proposed
>          > > interpretation of isolation on transport slice.
>          > >
>          > > Regards,
>          > > Greg
>          > >
>          > > On Sun, Apr 26, 2020 at 8:57 AM Joel Halpern Direct
>          > > <jmh.direct@joelhalpern.com
>         <mailto:jmh.direct@joelhalpern.com>
>         <mailto:jmh.direct@joelhalpern.com
>         <mailto:jmh.direct@joelhalpern.com>>>
>          > wrote:
>          > >
>          > >     Trimmed, in line.
>          > >     Joel
>          > >
>          > >     On 4/26/2020 11:08 AM, Dongjie (Jimmy) wrote:
>          > >      > Hi Joel,
>          > >      >
>          > >      > Please see some replies inline:
>          > >      >
>          > >      >> -----Original Message-----
>          > >      >> From: Teas [mailto:teas-bounces@ietf.org
>         <mailto:teas-bounces@ietf.org>
>          > >     <mailto:teas-bounces@ietf.org
>         <mailto:teas-bounces@ietf..org>>] On Behalf Of Joel M. Halpern
>          > >      >> Sent: Sunday, April 26, 2020 10:52 AM
>          > >      >> To: Zhenghaomian <zhenghaomian@huawei.com
>         <mailto:zhenghaomian@huawei.com>
>          > >     <mailto:zhenghaomian@huawei.com
>         <mailto:zhenghaomian@huawei.com>>>; teas@ietf.org
>         <mailto:teas@ietf.org>
>          > <mailto:teas@ietf.org <mailto:teas@ietf.org>>
>          > >      >> Subject: Re: [Teas] Network Slicing design team
>         definitions -
>          > >     isolation and
>          > >      >> resolution
>          > >      >>
>          > >     ....
>          > >      >> More importantly, it is not something the customer
>         has any way
>          > >     to verify.
>          > >      >> There is no test a customer can run that will
>         verify this.
>          > >      >> Making unverifiable promises is rarely a useful
>         thing to do.
>          > >      >
>          > >      > Totally agree that tools for verification is
>         important. As
>          > >     mentioned in Haomian's mail, isolation can be verified
>         with suitable
>          > >     tools which can be used to collect the information at
>         the necessary
>          > >     places with a suitable interval. And it is important
>         that customers
>          > >     can be provided with such tools to monitor the
>         performance and be
>          > >     informed of SLA violation.
>          > >
>          > >     As far as I can tell, the observable that you describe
>         is latency
>          > >     variation (or maybe loss).  Fine, describe the SLO in
>         terms of latency
>          > >     variation  (or loss).  Given that there are always
>         imperfections in
>          > the
>          > >     system, the customer may think that the issue is
>         isolation.  But
>          > >     what he
>          > >     can observe, and as far as I can tell what he cares
>         about, is delay
>          > >     variation, loss, or other factors that affect his traffic.
>          > >
>          > >     To use a different example, I have learned from the
>         advocates to hate
>          > >     bufferbloat.  But even their tests measure delay, delay
>         variation,
>          > >     etc..
>          > >     They then infer the presence of large buffers.  But in
>         fact, if the
>          > >     large buffers are present but never used, we would all
>         be happy.  So
>          > >     the
>          > >     SLO on this would be in terms of latency, latency
>         variation, loss, etc.
>          > >     Not bufferbloat.`
>          > >
>          > >     Yours,
>          > >     Joel
>          > >
>          > >      >
>          > >      > Best regards,
>          > >      > Jie
>          > >      >
>          > >      >>
>          > >      >> Yours,
>          > >      >> Joel
>          > >      >>
>          > >      >> PS: Note that I understand that operators get asked
>         for odd
>          > >     things mby
>          > >      >> customers.  But if we are going to define standards
>         to support
>          > >     it, we need to
>          > >      >> understand the actual need.
>          > >      >>
>          > >      >> On 4/25/2020 10:44 PM, Zhenghaomian wrote:
>          > >      >>> Not sure if I understand your question correctly.
>          > >      >>> Well, it's reasonable for people to request hard
>         isolation
>          > >     because 'I don't want
>          > >      >> my data to be transported together with other
>         people's data'.
>          > >      >>> For delivery this can be achieved by separating
>         physical
>          > >     devices/connections,
>          > >      >> which are visible to users. For example dedicated
>         boxes and
>          > >     fibers will guarantee
>          > >      >> the user's data is not mixed with others...
>          > >      >>>
>          > >      >>> Best wishes,
>          > >      >>> Haomian
>          > >      >>>
>          > >      >>> -----邮件原件-----
>          > >      >>> 发件人: Joel M. Halpern
>         [mailto:jmh@joelhalpern.com <mailto:jmh@joelhalpern.com>
>          > >     <mailto:jmh@joelhalpern.com <mailto:jmh@joelhalpern.com>>]
>          > >      >>> 发送时间: 2020年4月26日 10:34
>          > >      >>> 收件人: Zhenghaomian <zhenghaomian@huawei.com
>         <mailto:zhenghaomian@huawei.com>
>          > >     <mailto:zhenghaomian@huawei.com
>         <mailto:zhenghaomian@huawei.com>>>; teas@ietf.org
>         <mailto:teas@ietf.org>
>          > <mailto:teas@ietf.org <mailto:teas@ietf.org>>
>          > >      >>> 主题: Re: [Teas] Network Slicing design team
>         definitions -
>          > >     isolation and
>          > >      >>> resolution
>          > >      >>>
>          > >      >>> (trimmed)
>          > >      >>> What is the user perceivable effect that the user
>         is asking for
>          > >     when you say "if
>          > >      >> the user requests isolation"?
>          > >      >>>
>          > >      >>> Yours,
>          > >      >>> Joel
>          > >      >>>
>          > >      >>> On 4/25/2020 10:31 PM, Zhenghaomian wrote:
>          > >      >>>> Hi, Kiran, Joel,
>          > >      >>>>
>          > >      >>> ...
>          > >      >>>> BTW, regarding the isolation, I don't see the
>         necessity to
>          > >     argue whether it
>          > >      >> should be in SLO or not. The isolation itself, can
>         either be
>          > >     requested by the user
>          > >      >> of the transport slice (then from NBI of TSC) to
>         express the
>          > >     demand of reliability,
>          > >      >> or be offered by the provider of the transport
>         slice (then from
>          > >     the SBI of TSC) to
>          > >      >> achieve the SLO requested from the user. In other
>         words, if the
>          > >     user requests
>          > >      >> certain level of isolation in an SLO, such
>         isolation should be
>          > >     provided; if the user
>          > >      >> does not request certain level of isolation (no
>         isolation
>          > >     request in SLO), then
>          > >      >> there may be some isolation provided to satisfy the
>         user's
>          > request.
>          > >      >>>>
>          > >      >>>> Best wishes,
>          > >      >>>> Haomian
>          > >      >>
>          > >      >> _______________________________________________
>          > >      >> Teas mailing list
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>         <mailto:Teas@ietf.org <mailto:Teas@ietf.org>>
>          > >      >> https://www.ietf.org/mailman/listinfo/teas
>          > >
>          > >     _______________________________________________
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