Re: [spring] SRH scratch space (was Re: Question about SRv6 Insert function)

Robert Raszuk <> Wed, 11 December 2019 08:37 UTC

Return-Path: <>
Received: from localhost (localhost []) by (Postfix) with ESMTP id C003012088A for <>; Wed, 11 Dec 2019 00:37:24 -0800 (PST)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -1.998
X-Spam-Status: No, score=-1.998 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, 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=unavailable autolearn_force=no
Authentication-Results: (amavisd-new); dkim=pass (2048-bit key)
Received: from ([]) by localhost ( []) (amavisd-new, port 10024) with ESMTP id oYyOwKqLAi6N for <>; Wed, 11 Dec 2019 00:37:21 -0800 (PST)
Received: from ( [IPv6:2607:f8b0:4864:20::836]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by (Postfix) with ESMTPS id 7662D1207FE for <>; Wed, 11 Dec 2019 00:37:21 -0800 (PST)
Received: by with SMTP id t17so5556265qtr.7 for <>; Wed, 11 Dec 2019 00:37:21 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=175S71gXM/OCP/UK/HodHnwz4ToRtGQXCA83KUzQsE4=; b=V3pOU7eWNH0Q6U+5/AelH7ixXYxI39++LQzmW7YwIt9N2nlqT4sOaW9RP0DknPM9jZ y9yhm9Tsp63BFcfdbVvukkYfwKBqNGFEgm16veOkypXOAKYS6H80n0XUoOcKLazLhvi/ T3qnlEYv5dQUZCYb64uQJEQiy8GAtaIyDZOfXwulYoEo9Z4O20C+55aMC22gSN02D0Nj hPHymj9gu6rb4mbHLU/fWErbPa7XJqh0Tf9jSsHmCVvaoqvQXVahzR04lOv2HuvsGyrZ Z+yXz1Hq32Sg7TYPuJLLbyEl+uFaISMeYrAOmelOjz5ACsc5qWYAsI/L5/HH2LAMCZBk /FAw==
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=175S71gXM/OCP/UK/HodHnwz4ToRtGQXCA83KUzQsE4=; b=KK3if8V9XkcZcg/S+DVNDdPL4uMVVJrDkpB5TFqNNl0+g/cYcMV1UdH2CHq+sbfzEE F8Hzk/OS5FL/67W7uUJyUlKBEuS3S8uGjyOoM13nm6sKgY7O9PK3Vd92KiDs3lxiELfi PKoolma01I2+D7Wxexs69aciz8F3U6RpqCep4gIfDwxagSc1szKzBYMdyC6B8QoErSTU pNB7s7awmfZZd7p0bDJKCnHILYbTiA+vXK5IOvYJ+dYVQu2pikD6n3I7O30y7xZGa2Ym XKSM9mwFoNboo2LD7Y7IVfbdEGxzn7w5kYfMbdGQPdcqYZI3LeKqls86vNRvJ7cD1tq2 nI5g==
X-Gm-Message-State: APjAAAWnWWNYGFkAsb3ABkrEMAlHUuS+hQ6O+Tlrii4QryyvEkRGgDsF E/HXP26WRh/fJYee2FZUqUHaqEdvutrxdMgUzUStwA==
X-Google-Smtp-Source: APXvYqz6mUBfwXCw+A/kVNGsOXuRFESLhRJw7t/E7TOiM9+T8JJfW+MBx5p1eKGai0C7wfMtWRC7CcD8sF4cirGn1ik=
X-Received: by 2002:ac8:7491:: with SMTP id v17mr1695196qtq.154.1576053440467; Wed, 11 Dec 2019 00:37:20 -0800 (PST)
MIME-Version: 1.0
References: <> <> <> <> <> <28214_1567694772_5D711FB4_28214_238_1_53C29892C857584299CBF5D05346208A48BFA9F3@OPEXCAUBM43.corporate.adroot.infra.ftgroup> <> <1824_1575998223_5DEFD30F_1824_112_1_53C29892C857584299CBF5D05346208A48D24EBD@OPEXCAUBM43.corporate.adroot.infra.ftgroup> <> <> <> <> <>
In-Reply-To: <>
From: Robert Raszuk <>
Date: Wed, 11 Dec 2019 09:37:10 +0100
Message-ID: <>
To: Brian E Carpenter <>
Cc: Erik Kline <>, Suresh Krishnan <>, Ron Bonica <>, "" <>, "" <>, draft-voyer-6man-extension-header-insertion <>, Fernando Gont <>, draft-ietf-spring-srv6-network-programming <>
Content-Type: multipart/alternative; boundary="000000000000776e8a0599698906"
Archived-At: <>
Subject: Re: [spring] SRH scratch space (was Re: Question about SRv6 Insert function)
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: "Source Packet Routing in NetworkinG \(SPRING\)" <>
List-Unsubscribe: <>, <>
List-Archive: <>
List-Post: <>
List-Help: <>
List-Subscribe: <>, <>
X-List-Received-Date: Wed, 11 Dec 2019 08:37:25 -0000

Hi Brian,

> Each SR node (Segment Endpoint) is effectively applying new IPv6 encap so
> is already doing an insertion of new SRH
> That isn't "insertion" in the sense of draft-voyer.

Correct. But we are not discussing draft-voyer here.

I think recent mail threads prove that it is much better to discuss one
topic at a time rather then mix three different and pretty orthogonal
"issues" interchangeably.

>  . It's prepending an extra layer of encapsulation, which is indeed just
> fine and I don't think anyone here is objecting to it. The spring draft
> currently uses (IMHO) imprecise language, even in its pseudo-code, but if
> all it's doing is describing successive layers of encapsulation that's fine
> too. Wasted bytes perhaps, but that isn't an IETF problem.

Great that we agree.

> Whether prepending new headers, each with their own SRH, is the best way
> of doing service-based traffic engineering is another question. Having just
> reviewed draft-ietf-bess-nsh-bgp-control-plane for Gen-ART, I do believe
> there's more than one possible approach.

100% agreed. In fact as you may have seen I have another non data plane,
but control plane proposal posted:

Kind regards,