Re: [Isis-wg] removing Controlled Convergence sub-TLV from draft-ietf-isis-mrt-02

"Les Ginsberg (ginsberg)" <> Thu, 20 October 2016 20:43 UTC

Return-Path: <>
Received: from localhost (localhost []) by (Postfix) with ESMTP id F2EE7129678 for <>; Thu, 20 Oct 2016 13:43:59 -0700 (PDT)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -14.951
X-Spam-Status: No, score=-14.951 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_HI=-5, RCVD_IN_MSPIKE_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, RP_MATCHES_RCVD=-0.431, SPF_PASS=-0.001, USER_IN_DEF_DKIM_WL=-7.5] autolearn=ham autolearn_force=no
Authentication-Results: (amavisd-new); dkim=pass (1024-bit key)
Received: from ([]) by localhost ( []) (amavisd-new, port 10024) with ESMTP id afinOo6Xq6wY for <>; Thu, 20 Oct 2016 13:43:58 -0700 (PDT)
Received: from ( []) (using TLSv1.2 with cipher DHE-RSA-SEED-SHA (128/128 bits)) (No client certificate requested) by (Postfix) with ESMTPS id 2D3511294A4 for <>; Thu, 20 Oct 2016 13:43:58 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple;;; l=12347; q=dns/txt; s=iport; t=1476996238; x=1478205838; h=from:to:subject:date:message-id:references:in-reply-to: mime-version; bh=UxCopG3TaNb9oxXSucLsFSyijAwhxUGSi65uRymfWMA=; b=M4OVIfzC/luphGjBacR83Nq3uAlUZRTyM2HZgtrnoF1qBWgMJ5NSTz8v ZZnIe0M3mq7hbt7GnyU1kfexbv2u4+u6FXI+5KivBx8yz8pXeFhqvOMtq QElNecgdegA5hL22OWieZgK9fenvKxe/aKawK3VOjTi0wLbDRnOmuowQ5 o=;
X-IronPort-Anti-Spam-Filtered: true
X-IronPort-AV: E=Sophos;i="5.31,372,1473120000"; d="scan'208,217";a="162045116"
Received: from ([]) by with ESMTP/TLS/DHE-RSA-AES256-SHA; 20 Oct 2016 20:43:57 +0000
Received: from ( []) by (8.14.5/8.14.5) with ESMTP id u9KKhvLg027145 (version=TLSv1/SSLv3 cipher=AES256-SHA bits=256 verify=FAIL); Thu, 20 Oct 2016 20:43:57 GMT
Received: from ( by ( with Microsoft SMTP Server (TLS) id 15.0.1210.3; Thu, 20 Oct 2016 15:43:56 -0500
Received: from ([]) by ([]) with mapi id 15.00.1210.000; Thu, 20 Oct 2016 15:43:56 -0500
From: "Les Ginsberg (ginsberg)" <>
To: Chris Bowers <>, ISIS-WG <>
Thread-Topic: [Isis-wg] removing Controlled Convergence sub-TLV from draft-ietf-isis-mrt-02
Thread-Index: AdIoinEwvgg0c8IhSPibxPBzdXrJowChyCug
Date: Thu, 20 Oct 2016 20:43:56 +0000
Message-ID: <>
References: <>
In-Reply-To: <>
Accept-Language: en-US
Content-Language: en-US
x-ms-exchange-transport-fromentityheader: Hosted
x-originating-ip: []
Content-Type: multipart/alternative; boundary="_000_b6e1036655a545dc8c39d24f78a9a2c4XCHALN001ciscocom_"
MIME-Version: 1.0
Archived-At: <>
Subject: Re: [Isis-wg] removing Controlled Convergence sub-TLV from draft-ietf-isis-mrt-02
X-Mailman-Version: 2.1.17
Precedence: list
List-Id: IETF IS-IS working group <>
List-Unsubscribe: <>, <>
List-Archive: <>
List-Post: <>
List-Help: <>
List-Subscribe: <>, <>
X-List-Received-Date: Thu, 20 Oct 2016 20:44:00 -0000

Chris -

draft-bryant-rtgwg-param-sync introduces a new level of hierarchy in IS-IS by defining a generic "NWP" sub-TLV inside Router Capability TLV and then using a new registry to define sub-sub-TLVs.
I fail to see why this is necessary. While it is true that traditional IS-IS is limited to 255 sub-TLV codepoints for Router Capability TLV,  as of today we have only used 20+ of those codepoints - so we are in no danger of running out.  And sub-sub-TLV encoding becomes less efficient as it requires 2 extra bytes to encode the sub-sub-TLV wrapper.

If your argument is that you intend to use "NWP" for a large number of parameters then I immediately get concerned about what it is you have in mind that would quickly exhaust the sub-TLV space.

Please either drop the sub-sub-TLV proposal or be more transparent as to why you think it is needed.

I also note the new proposal does not include MTID associated w the convergence parameter - is that change intentional?


From: Isis-wg [] On Behalf Of Chris Bowers
Sent: Monday, October 17, 2016 8:42 AM
Subject: [Isis-wg] removing Controlled Convergence sub-TLV from draft-ietf-isis-mrt-02


The authors of draft-ietf-isis-mrt-02  are planning to remove the Controlled Convergence sub-TLV that draft,
and instead use on an equivalent extension being defined in:

Since the Controlled Convergence sub-TLV communicates information that may be useful for
applications other that MRT, it makes sense to have it in a separate document to allow it to be
better vetted in the context of those other applications.

I don't think that anyone has implemented the Controlled Convergence sub-TLV in draft-ietf-isis-mrt-02.
But if this is not the case, or anyone has another objection to removing it from draft-ietf-isis-mrt-02, please
raise that objection in the next week or so.