Re: [ippm] Review on draft-ietf-ippm-ioam-data-06

Vijay Rangarajan <vijayr@arista.com> Thu, 22 August 2019 14:23 UTC

Return-Path: <vijayr@arista.com>
X-Original-To: ippm@ietfa.amsl.com
Delivered-To: ippm@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 796B7120114 for <ippm@ietfa.amsl.com>; Thu, 22 Aug 2019 07:23:00 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -1.999
X-Spam-Level:
X-Spam-Status: No, score=-1.999 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, HTML_MESSAGE=0.001, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001] autolearn=ham autolearn_force=no
Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (2048-bit key) header.d=arista.com
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id yFdKb1cpLbts for <ippm@ietfa.amsl.com>; Thu, 22 Aug 2019 07:22:57 -0700 (PDT)
Received: from mail-vs1-xe2b.google.com (mail-vs1-xe2b.google.com [IPv6:2607:f8b0:4864:20::e2b]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 5893C120105 for <ippm@ietf.org>; Thu, 22 Aug 2019 07:22:57 -0700 (PDT)
Received: by mail-vs1-xe2b.google.com with SMTP id j25so3934531vsq.12 for <ippm@ietf.org>; Thu, 22 Aug 2019 07:22:57 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=arista.com; s=googlenew; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=Wi1g5kB3kDjgFTWzbV4taS1IAfRiuwTcYwh7BUpJF20=; b=Rmr+Ucsbb2ytRY2EygM6A43wK+zXqwR5YEQXUC+XPWEBdJwXLUqRqpCHBaux0GBNH9 rBVRe1hzOF5J5o4Ffpw7T8rvJBL2EpjIpK19dRkdwmSMaMn/AFrcfyc7XBupubanADBd eccp6qzE4TTybOdhp6lxYb2lRLDpdgGh/FYew1yTEwtQnteMMYmiouz6JjmhnPllCXmv z8FzrseOulxFpAu4g4mPyDrowSdFd7cciGa+WbC3/f/lWxoRuBv8B6sEWWmQJoxNYNbh ZPWVCzzKvOTFBLPeiqcTvgBBBuzAcuAdzZEoyf72huemXoK5DserThhqhyjhpTFjGSeI Fe5w==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=Wi1g5kB3kDjgFTWzbV4taS1IAfRiuwTcYwh7BUpJF20=; b=HzlcFIhl/YFs7WQmb1O1S0PTzV+NJ2YDC8LgtN95FdoNOxAtHszlkYwhYrKkt6hsbB hmtlox0gRa0utZB8mIb4u/3TOaiIaeSumveg+gGA/z9ZaSxJkdviVnu0O42eSPJupj/H KlzRUxo7p4WcRnlrZP/MTBTyMwG91IBuWmB+G0hJ7OPaSepkL9D+1lrVmL5WnTfalec2 AdYwS4Yv5u11Cs7LjX2HKCGd6+lz0psgRJItkzCwLzC8OC4+Begij+i20uCDr/KaDnBc 0uDH4GaPA3EFN6fn+AbugMlCYvoToi/Ami9BId744frMiRoOZIzji77HWeO94vOggaQ0 r3rA==
X-Gm-Message-State: APjAAAXiT0HnqodD1S5DUnKDY70A/c8hAUEcDJW/+uFDHTt699ez8Oaq BNZ6lh+yQtvZiayQNeyeaxTBFt6LdQvTxMD2ZKG5pw==
X-Google-Smtp-Source: APXvYqwI9KiHYmuD3R45/WExTvzZYd0JRoV9R+9jaLGpJY+vBxEEdi/x6x03AiGmQgVTbTgntdPQgcB8sxtsr6pHR1Q=
X-Received: by 2002:a05:6102:24c:: with SMTP id a12mr24273384vsq.226.1566483776131; Thu, 22 Aug 2019 07:22:56 -0700 (PDT)
MIME-Version: 1.0
References: <B5A76AB5-AE39-4771-9472-38454CF52152@broadcom.com> <CAGn858RE4p8gez+b0=9PSsZQ=Y1uZANno5V7tqSo=cuqY7AJLA@mail.gmail.com> <BD32CF3D-C6F3-4CF6-A618-C41ED0C4D1CB@cisco.com> <CAGn858SLr4vix18=09gXgsN-VOspBL=qZ2-q6dWyF5b3ASgCYA@mail.gmail.com> <BYAPR11MB25845CFB28F096937486F8D7DAA50@BYAPR11MB2584.namprd11.prod.outlook.com>
In-Reply-To: <BYAPR11MB25845CFB28F096937486F8D7DAA50@BYAPR11MB2584.namprd11.prod.outlook.com>
From: Vijay Rangarajan <vijayr@arista.com>
Date: Thu, 22 Aug 2019 19:52:44 +0530
Message-ID: <CAGn858QOPgXb=-WgWhXETKgEw5v1soo=JsDB+LemOr7G6DKB1A@mail.gmail.com>
To: "Frank Brockners (fbrockne)" <fbrockne@cisco.com>
Cc: "Carlos Pignataro (cpignata)" <cpignata@cisco.com>, Jai Kumar <jai.kumar@broadcom.com>, "draft-ietf-ippm-ioam-data@ietf.org" <draft-ietf-ippm-ioam-data@ietf.org>, IETF IPPM WG <ippm@ietf.org>, Hugh Holbrook <holbrook@arista.com>, Anoop Ghanwani <Anoop.Ghanwani@dell.com>, "OU, Heidi" <heidi.ou@alibaba-inc.com>, Surendra Anubolu <surendra.anubolu@broadcom.com>, John Lemon <john.lemon@broadcom.com>
Content-Type: multipart/alternative; boundary="000000000000061cf00590b56d05"
Archived-At: <https://mailarchive.ietf.org/arch/msg/ippm/kUKDQhlzwkiqwXznxiDwKOzrvLY>
X-Mailman-Approved-At: Thu, 22 Aug 2019 10:06:26 -0700
Subject: Re: [ippm] Review on draft-ietf-ippm-ioam-data-06
X-BeenThere: ippm@ietf.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: IETF IP Performance Metrics Working Group <ippm.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/ippm>, <mailto:ippm-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/ippm/>
List-Post: <mailto:ippm@ietf.org>
List-Help: <mailto:ippm-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/ippm>, <mailto:ippm-request@ietf.org?subject=subscribe>
X-List-Received-Date: Thu, 22 Aug 2019 14:23:00 -0000

Hi Frank:
Thanks, I knew I was missing something.
So basically what you are saying is - let's say we have a UDP packet, we
are just going to stick in the GRE header and IOAM Header and Metadata
in-between the original IP and UDP headers?

So, the next protocol in the IOAM Header should indicate the L4 protocol -
i.e UDP/TCP?
Looking at https://datatracker.ietf.org/doc/draft-weis-ippm-ioam-eth/, it
actually defines the "Next protocol" in the IOAM header to be an ethertype
value?

Thanks,
Vijay


On Thu, Aug 22, 2019 at 6:22 PM Frank Brockners (fbrockne) <
fbrockne@cisco.com> wrote:

> Hi Vijay,
>
>
>
> note that you don’t necessarily need to “tunnel” – you can just use the
> GRE header to sequence-in IOAM.
>
>
>
> Cheers, Frank
>
>
>
> *From:* Vijay Rangarajan <vijayr@arista.com>
> *Sent:* Donnerstag, 22. August 2019 05:31
> *To:* Carlos Pignataro (cpignata) <cpignata@cisco.com>
> *Cc:* Jai Kumar <jai.kumar@broadcom.com>om>;
> draft-ietf-ippm-ioam-data@ietf.org; IETF IPPM WG <ippm@ietf.org>rg>; Frank
> Brockners (fbrockne) <fbrockne@cisco.com>om>; Hugh Holbrook <
> holbrook@arista.com>gt;; Anoop Ghanwani <Anoop.Ghanwani@dell.com>om>; OU, Heidi
> <heidi.ou@alibaba-inc.com>om>; Surendra Anubolu <
> surendra.anubolu@broadcom.com>gt;; John Lemon <john.lemon@broadcom.com>
> *Subject:* Re: [ippm] Review on draft-ietf-ippm-ioam-data-06
>
>
>
> Thanks Carlos, for pointing me to the draft.
>
>
>
> Based on my understanding of the two drafts I have the following questions
> and concerns:
>
>    1. If I understand correctly, to deploy inband telemetry, we would
>    need to construct GRE tunnels coinciding with the IOAM domain?
>    2. GRE typically requires configuration to provision the tunnels.
>    Provisioning and managing these tunnels and keeping these updated as the
>    network grows/shrinks could be a significant overhead.
>    3. In order to get the benefit of telemetry, we are imposing a change
>    in forwarding protocol/topology and configuration - which, I feel is not
>    desirable. For example, a customer might have basic L3 routing enabled and
>    the expectation would be for inband telemetry to work seamlessly, without
>    having to revamp the network with GRE tunnels and such. This could be a
>    significant barrier to deployment.
>    4. If sampling is used to select packets for performing IOAM encap, is
>    the expectation that only sampled IOAM packets go through GRE encap? Or all
>    data packets?
>    5. Due to network nodes inserting the IOAM data, the inner L3/L4
>    headers keep getting pushed deeper. I would imagine this gets challenging
>    for ASICs to access these fields for hashing/load balancing.
>    6. Assuming only a subset of packets in a flow are subject to IOAM
>    (based on sampling), how do we ensure these packets take the same network
>    path as the rest of the packets in the flow?
>
> Thanks,
>
> Vijay
>
>
>
>
>
> On Wed, Aug 21, 2019 at 5:04 PM Carlos Pignataro (cpignata) <
> cpignata@cisco.com> wrote:
>
> Hello, Vijay,
>
>
>
> Please see https://datatracker.ietf.org/doc/draft-weis-ippm-ioam-eth/,
> and the document this replaces.
>
>
>
> Thanks!
>
> Thumb typed by Carlos Pignataro.
>
> Excuze typofraphicak errows
>
>
> 2019/08/21 6:35、Vijay Rangarajan <vijayr@arista.com>のメールt;のメール:
>
> Hello all:
>
> Apologise if this has been previously discussed.
>
> In reading "draft-ietf-ippm-ioam-data-06", I don't see mention of GRE
> encap. The draft, in fact in Sec 3, says the following - "The in-situ OAM
> data field can be transported by a variety of transport protocols,
> including NSH, Segment Routing, Geneve, IPv6, or IPv4.  Specification
> details for these different transport protocols are outside the scope of
> this document."
>
>
>
> Is there another document, or a description somewhere, that talks about
> how IOAM is proposed to be carried in GRE? what would be the GRE payload,
> the GRE protocol type etc?
>
>
>
> Thanks,
>
> Vijay
>
>
>
>
>
> On Wed, Aug 21, 2019 at 7:52 AM Jai Kumar <jai.kumar@broadcom.com> wrote:
>
> Hello Frank,
>
>
>
> This is in context of our conversation at IETF105. My goal is to provide
> input and improve current IOAM data draft with the learnings we had with
> IFA deployment.
>
> This feedback is based on various customer interactions and concerns
> raised by them wrt IOAM. Each feedback is a longer topic and I am starting
> this thread as a summary email. This is just highlighting the issues and
> not yet proposing any solution.
>
>
>
>
>
> Feedback 1:
>
> Section 4.2.1 Pre-allocated and Incremental Trace Options
>
> Pre-allocated and incremental trace option is 8Bytes long. This can be
> easily reduced to 4Bytes.
>
> There is a feedback that pre-allocated option is really not needed and
> either be removed or made optional.
>
> Given that deployments are sensitive to the IOAM overhead (specially in 5G
> deployments), it’s a 50% fixed overhead savings on a per packet basis.
>
>
>
>
>
> Feedback 2:
> Section 4.1 IOAM Namespaces
>
> Namespaces should be treated as templates (similar to IPFIX template
> record formats). This is more flexible way of enumerating data. 64K
> namespace id is a very large namespace and can be reduced to 64 IANA
> specified name spaces. Separate private name space can be allowed instead
> of interleaving of opaque data in the IANA allocated name space as
> suggested in the current draft “opaque state snapshot”.
>
> https://tools.ietf.org/html/rfc7011#section-3.4
>
>
>
> Feedback 3:
>
> Section 4.2.1 Pre-allocated and Incremental Trace Options
>
> IOAM-Trace-Type:  A 24-bit identifier which specifies which data
>
>       types are used in this node data list.
>
> This is the most contentious of all. In the current proposal, as new data
> fields are added, there is a corresponding trace type bit need in the
> header. This essentially means that all possible data fields need to be
> enumerated. Given that we there are 64K names spaces allowed, I don’t see
> how we can fit all possible data fields in this 24bit vector. I know there
> was a suggestion of keeping last bit as an extension bit but it is still
> scalable and/or easy to implement in hardware. Besides this the data fields
> are not annotated/encoded with the data type, something like in IPFIX
> https://tools.ietf.org/html/rfc7011#section-6.1
>
>
>
> Feedback 4:
>
> There is no version field in the data header and this will make
> interoperability challenging. Standard will evolve and headers bit
> definition and/or trace type will change and without version field HW will
> not be able to correctly handle the IOAM data headers.
>
>
>
> Feedback 5:
>
> Handling of TCP/UDP traffic using GRE encap is not acceptable. Here are
> some of the issues I can think of
>
>    - GRE encaped IOAM packets will traverse a different network path then
>    the original packet
>    - Not all packets can be GRE encaped to avoid the previous problem,
>    due to wastage of network bandwidth (typically sampled traffic is used for
>    IOAM). What about native GRE traffic, will it get further encaped in
>    another GRE tunnel and so forth.
>    - IP header protocol will point to GRE IP proto and IOAM ethertype
>    (pending allocation by IEEE) need to be read from the GRE header to detect
>    an IOAM packet. This means parsing performance penalty for all regular GRE
>    (non IOAM) traffic.
>
>
>
> Thanks,
>
> -Jai
>
>
>
>