Re: [bess] Shepherd's review of draft-ietf-bess-mvpn-fast-failover
<slitkows.ietf@gmail.com> Tue, 07 January 2020 13:59 UTC
Return-Path: <slitkows.ietf@gmail.com>
X-Original-To: bess@ietfa.amsl.com
Delivered-To: bess@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 4E05612010D; Tue, 7 Jan 2020 05:59:35 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -0.998
X-Spam-Level:
X-Spam-Status: No, score=-0.998 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, FREEMAIL_FROM=0.001, FREEMAIL_REPLY=1, HTML_MESSAGE=0.001, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001] autolearn=no autolearn_force=no
Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (2048-bit key) header.d=gmail.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 SUvu3bfoK_BT; Tue, 7 Jan 2020 05:59:32 -0800 (PST)
Received: from mail-wm1-x32d.google.com (mail-wm1-x32d.google.com [IPv6:2a00:1450:4864:20::32d]) (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 E4B5B120120; Tue, 7 Jan 2020 05:59:31 -0800 (PST)
Received: by mail-wm1-x32d.google.com with SMTP id a5so19078365wmb.0; Tue, 07 Jan 2020 05:59:31 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:references:in-reply-to:subject:date:message-id :mime-version:thread-index:content-language; bh=t91gKV2lj8VPzLPu8D7pCJtMAS6SrGcMjpAkra7p9h4=; b=d7zfq9O1CiXHdBU12zo/M8ZUr1qawR2VWi0R53FCrt2jd6qO5mwhG9nHiiTxo2AFso yRlWvZQo2aJA6v/FpE5h3WRwGGbQdHzfJpXwBswjZ/5d/3yfTvuCmQPzhCZ6dvOkRpGF 3a8Q/E0ydbNMYMSXcpsa0XKYHm05W7b7ue4km0Lic8vcAyI1MIiBn/LEMSxuqepFqPCN bMCM6EoHzMn1z8ridziyWApWfSNGtYRP/tMoxGKJmiVebUPN94VNfRK342kwkcCefU27 V+/nq+jgepY0iqUBLPSUfx3CNyDGwHoQOHu1b8/jQJ6sIXRZVpevwqIQDyIbK+t3TK0v NKcQ==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:references:in-reply-to:subject:date :message-id:mime-version:thread-index:content-language; bh=t91gKV2lj8VPzLPu8D7pCJtMAS6SrGcMjpAkra7p9h4=; b=ILtuD4ikkJFvpR7qANlVfkCMHSslj17g8vtjfMzaqSx2EMwjW+RMvnhXL0McXwhjwQ rQlFFYPIzBrliUAQdvTnJHK0bfBFjnycAGnDxCTg5HSMEJmTZuW4q72gUb7vzP+ZV5FT epAIOnxx+mJdzEuogZxz7U8ps5gCxIXmXZReo1UaJ6Uw2wPvFUpcSY+vS7JIO2f9kGJp chD3CqpE9KeBbOYOnGe0BUm2Nj9w9uwFgyZ2pyIqs68u9zPnCU//vgaVA1DhhUu3+Xv9 66uX+dspbvb5+om+O63WfstzHtIA7fFgPBtviuXinhAuWJ6vB+RoG3BaB9cyxi8bIOgj T74w==
X-Gm-Message-State: APjAAAXlTiJokDb13tdx1eeSVVFIN6aY4LDFKve2WqYtj0y4TelTvrVY eJpss+SvgVW1ivkcrWa+Mk2Trcs=
X-Google-Smtp-Source: APXvYqwwA0+CD1TS5E2yO8mfZC/AFVhPgxwrUkQ2jxmSAtP1l8TCK8gwh6bhFauhSj/XWNCIVk+PqQ==
X-Received: by 2002:a05:600c:224a:: with SMTP id a10mr41484415wmm.143.1578405570002; Tue, 07 Jan 2020 05:59:30 -0800 (PST)
Received: from SLITKOWS3YYU6 ([173.38.220.49]) by smtp.gmail.com with ESMTPSA id w8sm27238264wmm.0.2020.01.07.05.59.28 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 07 Jan 2020 05:59:29 -0800 (PST)
From: slitkows.ietf@gmail.com
To: 'Greg Mirsky' <gregimirsky@gmail.com>
Cc: 'BESS' <bess@ietf.org>, bess-chairs@ietf.org
References: <CA+RyBmWOYUnrzrb=M=dvHpn-huh_WFJURF0spOzX_752V0gkVg@mail.gmail.com> <04f301d5c4a0$6cd81690$468843b0$@gmail.com> <CA+RyBmVsFVz42sbPRF=oJ=wH-dVrZRaMgf+Kqr6ne5SO3HC0+Q@mail.gmail.com>
In-Reply-To: <CA+RyBmVsFVz42sbPRF=oJ=wH-dVrZRaMgf+Kqr6ne5SO3HC0+Q@mail.gmail.com>
Date: Tue, 07 Jan 2020 14:59:27 +0100
Message-ID: <068e01d5c562$ad9cf7f0$08d6e7d0$@gmail.com>
MIME-Version: 1.0
Content-Type: multipart/alternative; boundary="----=_NextPart_000_068F_01D5C56B.0F62E690"
X-Mailer: Microsoft Outlook 16.0
Thread-Index: AQITf8rm7BVfQAwI1oQ62g9CZIXWDgLbFqY8AhKUgq6nPFbSIA==
Content-Language: fr
Archived-At: <https://mailarchive.ietf.org/arch/msg/bess/UNgbxMuyIBWGlBy_VqMXZgOHotM>
Subject: Re: [bess] Shepherd's review of draft-ietf-bess-mvpn-fast-failover
X-BeenThere: bess@ietf.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: BGP-Enabled ServiceS working group discussion list <bess.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/bess>, <mailto:bess-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/bess/>
List-Post: <mailto:bess@ietf.org>
List-Help: <mailto:bess-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/bess>, <mailto:bess-request@ietf.org?subject=subscribe>
X-List-Received-Date: Tue, 07 Jan 2020 13:59:35 -0000
Hi Greg, More inline, From: Greg Mirsky <gregimirsky@gmail.com <mailto:gregimirsky@gmail.com> > Sent: mercredi 4 décembre 2019 23:22 To: slitkows.ietf@gmail.com <mailto:slitkows.ietf@gmail.com> ; BESS <bess@ietf.org <mailto:bess@ietf.org> >; bess-chairs@ietf.org <mailto:bess-chairs@ietf.org> Subject: RE: Shepherd's review of draft-ietf-bess-mvpn-fast-failover Hi Stephane, thank you for the review and your thoughtful comments. Please find my answers and notes in-lined under GIM>> tag. Attached, please find the diff and copy of the working version. Regards, Greg Hi, Please find below my review of the document. Nits: Section 3.1.1: As the document is standard track, could you introduce normative language in the expected behavior description ? GIM2>> My apologies, I've pasted the same text twice. I propose to remove "may be omitted" altogether. Hence the updated text: If BGP next-hop tracking is done for VPN routes and the root address of a given tunnel happens to be the same as the next-hop address in the BGP auto-discovery route advertising the tunnel, then the use of this mechanism for the tunnel will not bring any specific benefit. Do you see this version without any normative language as acceptable? [SLI] Looks good thanks Section 3.1.2: As the document is standard track, could you introduce normative language in the expected behavior description ? “This method should not be used”. Wouldn’t this be a normative statement ? GIM>> Would the following modification of the text be acceptable: OLD TEXT: This method should not be used when there is a fast restoration mechanism (such as MPLS FRR [RFC4090]) in place for the link. NEW TEXT: Using this method when a fast restoration mechanism (such as MPLS FRR [RFC4090]) is in place for the link requires careful consideration and coordination of defect detection intervals for the link and the tunnel. In many cases, it is not practical to use both methods at the same time. [SLI] Are we strongly disencouraging the practice ? if yes, “it is not practical” is a bit too soft. I’m wondering if “is NOT RECOMMENDED” could be a good wording. But it is up to you. GIM2>> The use of OAM in multi-layer fashion is a question I'd be interested to discuss. But I feel that it deserves a separate document and would prefer to leave the text as a note of caution for now. [SLI] Ok Section 3.1.4: As the document is standard track, could you introduce normative language in the expected behavior description ? GIM>> Updating to the normative language as follows: OLD TEXT: A PE can be removed from the UMH candidate list for a given (C-S, C-G) if the P-tunnel (I or S, depending) for this (S, G) is leaf triggered (PIM, mLDP), but for some reason internal to the protocol the upstream one-hop branch of the tunnel from P to PE cannot be built. In this case, the downstream PE can immediately update its UMH when the reachability condition changes. NEW TEXT: A PE MAY be removed from the UMH candidate list for a given (C-S, C-G) if the P-tunnel (I-PMSI or S-PMSI) for this (S, G) is leaf- triggered (PIM, mLDP), but for some reason internal to the protocol the upstream one-hop branch of the tunnel from P to PE cannot be built. In this case, the downstream PE MAY immediately update its UMH when the reachability condition changes. [SLI] I understand the first “MAY” as optional feature, however the second “MAY” is more a “SHOULD” IMO. Thoughts? GIM2>> Thank you for the clarification. The UMH list will certainly be updated once the reachability of the downstream PE changes. In some scenarios, such an update may be immediate, i.e., ASAP, but in some, it might be better to delay it. Would you suggest adding a note about the option to delay the update? [SLI] Could you check with Jeffrey Zhang on this point ? I’m not enough expert here to tell what may be the best option. On my side, I just want the text to be clear 😊 Section 3.1.6: As the document is standard track, could you introduce normative language in the expected behavior description ? GIM>> Sub-sections of 3.1.6 define the use of RFC 8562 and the new attribute. In the introduction to these sub-sections, I propose s/can/MAY/ >From a wider perspective, do you foresee other use case of signaling BFD information in BGP ? I’m just wondering if we may need something extensible for future use or not. GIM>> Great question. BGP, and I'm speculating here, may be used to for other BFD-related scenarios. I think that we may use the Flags field. [SLI] Is it enough or should you add some optional TLVs behind the discriminator ? (with nothing defined yet). GIM2>> Great idea, thank you! Please see the updated figure and the text: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | BFD Mode | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | BFD Discriminator | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Reserved TLV | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Format of the BFD Discriminator Attribute Where: BFD Mode is the one octet long field. This specification defines the P2MP value (TBA3) Section 7.1. Reserved field is three octets long and the value MUST be zeroed on transmission and ignored on receipt. BFD Discriminator is four octets long field. Reserved TLV field is four octets long. It MAY be used for future extensions of the BFD Discriminator Attribute using Type-Length- Value format. This specification defines that the value in Reserved TLV field MUST be zeroed on transmission and ignored on receipt. [SLI] If your field is 4-bytes long, it is not extensible, I was thinking of options encoded as TLVs. If there is no TLV, the attribute ends on BFD discriminator, the attribute length should tell if there are TLVs or not. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | BFD Mode | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | BFD Discriminator | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | optional TLVs | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Another point I have missed, you should define error handling procedures for your attribute as per RFC7606.
- Re: [bess] Shepherd's review of draft-ietf-bess-m… Greg Mirsky
- Re: [bess] Shepherd's review of draft-ietf-bess-m… slitkows.ietf
- Re: [bess] Shepherd's review of draft-ietf-bess-m… Greg Mirsky
- [bess] Shepherd's review of draft-ietf-bess-mvpn-… slitkows.ietf
- Re: [bess] Shepherd's review of draft-ietf-bess-m… Greg Mirsky
- Re: [bess] Shepherd's review of draft-ietf-bess-m… slitkows.ietf
- Re: [bess] Shepherd's review of draft-ietf-bess-m… Greg Mirsky
- Re: [bess] Shepherd's review of draft-ietf-bess-m… Greg Mirsky
- Re: [bess] Shepherd's review of draft-ietf-bess-m… slitkows.ietf
- Re: [bess] Shepherd's review of draft-ietf-bess-m… Greg Mirsky
- Re: [bess] Shepherd's review of draft-ietf-bess-m… Jeffrey (Zhaohui) Zhang
- Re: [bess] Shepherd's review of draft-ietf-bess-m… slitkows.ietf
- Re: [bess] Shepherd's review of draft-ietf-bess-m… Greg Mirsky
- Re: [bess] Shepherd's review of draft-ietf-bess-m… Jeffrey (Zhaohui) Zhang
- Re: [bess] Shepherd's review of draft-ietf-bess-m… Greg Mirsky
- Re: [bess] Shepherd's review of draft-ietf-bess-m… Jeffrey (Zhaohui) Zhang
- Re: [bess] Shepherd's review of draft-ietf-bess-m… Greg Mirsky
- Re: [bess] Shepherd's review of draft-ietf-bess-m… Greg Mirsky
- Re: [bess] Shepherd's review of draft-ietf-bess-m… slitkows.ietf
- Re: [bess] Shepherd's review of draft-ietf-bess-m… Greg Mirsky