Re: [Teas] Thoughts about draft-nsdt-teas-ietf-network-slice-definition and isolation

Stewart Bryant <> Tue, 17 November 2020 10:22 UTC

Return-Path: <>
Received: from localhost (localhost []) by (Postfix) with ESMTP id 7F8DF3A0E50; Tue, 17 Nov 2020 02:22:32 -0800 (PST)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -1.097
X-Spam-Status: No, score=-1.097 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001, FREEMAIL_REPLY=1, HTML_MESSAGE=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001] autolearn=no autolearn_force=no
Authentication-Results: (amavisd-new); dkim=pass (2048-bit key)
Received: from ([]) by localhost ( []) (amavisd-new, port 10024) with ESMTP id LkhcmGnZtsWl; Tue, 17 Nov 2020 02:22:30 -0800 (PST)
Received: from ( [IPv6:2a00:1450:4864:20::331]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by (Postfix) with ESMTPS id 9165D3A0E4F; Tue, 17 Nov 2020 02:22:30 -0800 (PST)
Received: by with SMTP id a3so2684334wmb.5; Tue, 17 Nov 2020 02:22:30 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;; s=20161025; h=from:message-id:mime-version:subject:date:in-reply-to:cc:to :references; bh=ddh70PZD4pl4y30pHl3xUQ92BCIPnxdRT9rHThGc6Os=; b=CUuivSyO09AZ5KfyQg9Esn+2cwUzGJ/kaFnqpNaypW1Mc4RU7ImWEFDgjdu6ZrH0U1 nD2u6m+y/b6wbqD6naD7sn5N2iMnUEpFwTRSG4Eh/YeJQtOOW0h9v/cRvgW1qzg/DhWA KFGN9Thk7FpBssgQZQSNfg5rA7q18iN99CVPafUQyH23HBzlioMnRFtAbk0coJJ0n9jA R/STA555LEmIplkohdetTj1+M11MogzEyObMniQUO6TMLwd1nlRDPnXt07xYm2g/d04z Bxb2XTlj9zANO/7lKgPvhERkniqcLHo0t8zNIeQVP2FK8uC8jIDakm9AXihqZWvMgcAK jxIA==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;; s=20161025; h=x-gm-message-state:from:message-id:mime-version:subject:date :in-reply-to:cc:to:references; bh=ddh70PZD4pl4y30pHl3xUQ92BCIPnxdRT9rHThGc6Os=; b=eyZI/+f6VPDWQHXfQmHlpg5x+M8m7y8FZ8+CUKBv3lKE0FL849OrlVeB7+58f1/0cG rF8bgx6fzeuiAA/N3rYJRbU0VyFrgXBNixpC5owiVg3p4Q0HCP9QPEOx6W8vyojgqKxr CMDYtqpJkA2RpPIPaJgzRbRDSJ0kBZ3mR1MA+KAouNQ0J7yJLrvnGfo8QwfVPzpbD2xc dyP/I5VUP2rZiVjOEqO9OkBkz8sE+5tcweZhclBhy5y6gIJNJLYtuiSSVqPa5uEL8S9e Zo2+fUDkYUFUK4kAF0R0/e4iYQ/GPQFXlnMWWZsI0Dz+zy+ax5bvkYY0zTjfy/RXvFpC X3WQ==
X-Gm-Message-State: AOAM530KtU2kt0qqsR+NRtn7F60EN4AaK5YKI8XXC2DaQswtohP+DI4N rDyLjzYeq561NSrNuJ0Jilk=
X-Google-Smtp-Source: ABdhPJyOBORFZIQN07tazT61tActj5tM7vfQJNJ8M7k7Kny5wfv2LVGqGBtGMP6EQUHAbilEFB8Ajw==
X-Received: by 2002:a05:600c:d2:: with SMTP id u18mr3581669wmm.102.1605608548852; Tue, 17 Nov 2020 02:22:28 -0800 (PST)
Received: from ([2a00:23c5:3395:c901:a9c3:7842:c90b:a6e1]) by with ESMTPSA id f5sm27795343wrg.32.2020. (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Tue, 17 Nov 2020 02:22:28 -0800 (PST)
From: Stewart Bryant <>
Message-Id: <>
Content-Type: multipart/alternative; boundary="Apple-Mail=_4F58019C-8CFC-4929-9E92-B084F675A914"
Mime-Version: 1.0 (Mac OS X Mail 13.4 \(3608.\))
Date: Tue, 17 Nov 2020 10:22:27 +0000
In-Reply-To: <>
Cc: Stewart Bryant <>,,
To: Joel Halpern Direct <>
References: <059e01d6b6ce$0f74a830$2e5df890$> <> <13178999-9168-46fb-8455-36d4d5683a2e@Spark> <> <a9d968ed-90af-4889-8cc8-bc57b76edbf3@Spark> <> <>
X-Mailer: Apple Mail (2.3608.
Archived-At: <>
Subject: Re: [Teas] Thoughts about draft-nsdt-teas-ietf-network-slice-definition and isolation
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Traffic Engineering Architecture and Signaling working group discussion list <>
List-Unsubscribe: <>, <>
List-Archive: <>
List-Post: <>
List-Help: <>
List-Subscribe: <>, <>
X-List-Received-Date: Tue, 17 Nov 2020 10:22:33 -0000

They are terms from the timing world where you look at a defect in terms of its probability within a window within a larger observation period.,_NSN).pdf <,_NSN).pdf>

ITU define MTIE in G.810, but they are looking at a different class of application (frequency transfer), but I think the concept translates over here.

If you look at slide 5 “MTIE of a practical packet clock” you get the idea, but I think it needs expanding and applying to other characteristics. 

Now some of the error sources will be within the slice, but we also need to worry about error sources induced from outside the slice.

Best regards


> On 17 Nov 2020, at 10:05, Joel Halpern Direct <> wrote:
> Stewart, I think you are raising an interesting question, but one where I got lost part way through.
> Can you elaborate one what you mean by "something analogous to MTIE and TDEV to describe packet and network interaction".
> Thank you,
> Joel
> On 11/17/2020 4:57 AM, Stewart Bryant wrote:
>>> On 9 Nov 2020, at 23:37, Jeff Tantsura < <>> wrote:
>>> I don’t think mixing performance objectives with isolation is a great idea though,
>>> an SLA doesn’t change because there’s someone else sharing infrastructure with you, it is well understood that any changes within other customers should not affect you.
>> No, but in this class of networks the interaction between customers may be a lot more sensitive and detailed than we are used to. For example the single metrics that we normally associate with delay and jitter will likely become a mask in the same way that time and frequency transfer system find necessary to completely specify and instrument the behaviour of the subs system. We will likely need something analogous to MTIE and TDEV to describe packet and network interaction.
>> I therefore think it is useful to have an umbrella term for concept and the set of metrics that are of necessity more complex and critical than we are used to.
>> A possible alternative umbrella term is network cross talk. We understand the concept of crosstalk at the physical layer. The concept here in terms of performance is that packets do not interact at the micro level as well as the more normal macro level.
>> However, isolation has other feature that we need to think about under this umbrella, for example the need to only mix certain types of traffic allow (or exclude) traffic to flow over certain geographies or through nodes manufactured by certain countries. We do not have to agree with these constraints, but we need to accept that they are becoming a reality.
>> Now we could achieve the above by buying dedicated fibre or dedicated hardware, but that that does not support economies of scale.
>> I would be fine with us using a term other than isolation, but I think it is worthwhile highlighting that we are not in “ordinary” SLA territory with this, but that it is more complex and more detailed, and a top level term to group these characteristics is in my view helpful.
>> Best regards
>> Stewart