Re: [Bier] Comments on draft-chen-bier-frr-02.

Tony Przygienda <> Wed, 17 March 2021 16:48 UTC

Return-Path: <>
Received: from localhost (localhost []) by (Postfix) with ESMTP id D5CA93A09E9 for <>; Wed, 17 Mar 2021 09:48:33 -0700 (PDT)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -2.098
X-Spam-Status: No, score=-2.098 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, HTML_MESSAGE=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001] autolearn=unavailable autolearn_force=no
Authentication-Results: (amavisd-new); dkim=pass (2048-bit key)
Received: from ([]) by localhost ( []) (amavisd-new, port 10024) with ESMTP id nVvtfBhO-gJh for <>; Wed, 17 Mar 2021 09:48:32 -0700 (PDT)
Received: from ( [IPv6:2607:f8b0:4864:20::d2e]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by (Postfix) with ESMTPS id 3C4EA3A09E7 for <>; Wed, 17 Mar 2021 09:48:32 -0700 (PDT)
Received: by with SMTP id u20so41647764iot.9 for <>; Wed, 17 Mar 2021 09:48:32 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=Mn6CDhvgMI5Pa9TijiIBOXiTzMtcJrSz62PpOXr/x4w=; b=R+ZnOpLcVLzr8QUNelV6BJxwAJdpyMDQYtYRGsdjTAApglbDLgDa5R+BEn9xRfGGC4 4bsRlXsgfNLPf/JtUiNjqlpvKYOYz0F+MMcQit83wCmW458aQ6VvO3oBMLQxgtiH+t+M E2eyPOd/CCOKpA7d9PXIAoF/NQDu5JsAEdNRTgpirTB4HPpdWsVlb4Lv0+VjEqk/LIqR wo7t5t1oOq5pR20fN/jfspn318KUNsyb4G2ycKq42ua9MLdOSlRk8rHBjwI1qAQ1N/wn W4uOPx7H8efkehMvJpAxqmRTxIaSmRQBTHIFBqPEvB2qrUip+YqZPKJz9MlgrpuXIoqH st1w==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=Mn6CDhvgMI5Pa9TijiIBOXiTzMtcJrSz62PpOXr/x4w=; b=fzdE0jDg5ArEu+PlmFVxpmkPuMzAPZgVE3DIzNXKdjs3lzUa6R4gB2TH1MNxEmFAL/ l+zbFfe+EWqkamqr28S2DyOLoGxQ+9ouAhC/hrA3OzOgDjdy//8Z984MspI3/o2W6m5Y jrw+l7iEFdSXc43pMARzenLFGN0SbjbghXmiKqNJavql4i9d9irTh0eRWq4qZhxrEPU4 A9Dn3E5VH+NBZt7F10/iJXIJll4fgRF+7AEJXCwDM7OaUaNRTQjLBpxX88WL4jhtWdB8 Kd98cCk2gNQ9SXfK0VvIiXH63+DwGCqUz/PdsIVbHE406zv8npoUCDj+qdvESBkZ6Pny nu7Q==
X-Gm-Message-State: AOAM533Xk76fAh7NNwIT1aBau7ViFn6Rtx65h5UTWvSaZ/MrY704Qkmv vE52uhb7nMFqbD84hX72qcwSlg0QjPG+lZ0Jaic=
X-Google-Smtp-Source: ABdhPJxz3p6T0uHJS/AWkZlcgbTjeqJZ6KAOw2ad4Rdfc6vWm0rJ4Wty95eiQ7qsYEZA4JMMt7iaaM0c5rqf8YJrWig=
X-Received: by 2002:a6b:ec14:: with SMTP id c20mr7670420ioh.122.1615999708882; Wed, 17 Mar 2021 09:48:28 -0700 (PDT)
MIME-Version: 1.0
References: <> <> <>
In-Reply-To: <>
From: Tony Przygienda <>
Date: Wed, 17 Mar 2021 17:47:53 +0100
Message-ID: <>
To: "Jeffrey (Zhaohui) Zhang" <>
Cc: Huaimo Chen <>, "" <>
Content-Type: multipart/alternative; boundary="0000000000009ae91b05bdbe4012"
Archived-At: <>
Subject: Re: [Bier] Comments on draft-chen-bier-frr-02.
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: "\"Bit Indexed Explicit Replication discussion list\"" <>
List-Unsubscribe: <>, <>
List-Archive: <>
List-Post: <>
List-Help: <>
List-Subscribe: <>, <>
X-List-Received-Date: Wed, 17 Mar 2021 16:48:34 -0000

> In my view, the following does handle multiple failures to maximum extent:
> zzh> A better way is to simply have a single BIFT for both normal and FRR
> forwarding. Each entry has some ECMP and/or primary/backup branches,
> and you simply use another ECMP branch or a backup branch when the
> normally used branch fails. A backup branch can go through completely
> different nbr, or go through the same neighbor but via a tunnel.
> Consider that and the cost associated with building/maintaining multiple
> BIFTs, I would argue that the multiple per-nbr FRR BIFT approach, while
> perhaps acceptable for a particular implementation, is not ready yet for WG
> adoption.
> Please note that I am not arguing against LFA based FRR. I am just saying
> that the reference model of a single BIFT with ECMP/primary/backup branches
> for an entry is the best baseline.

as participant and from experience


in that sense merling's paper seems a better model to talk about stuff.
Plus the technical concerns about the compressed multiple BIFTs on multiple

-- tony