Re: [mpls] [Lsr] Working Group Last Call for "Signaling Entropy Label Capability and Entropy Readable Label-stack Depth Using OSPF" - draft-ietf-ospf-mpls-elc-08

" 徐小虎(义先) " <> Thu, 12 September 2019 02:38 UTC

Return-Path: <>
Received: from localhost (localhost []) by (Postfix) with ESMTP id 1461A120098; Wed, 11 Sep 2019 19:38:34 -0700 (PDT)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -1.996
X-Spam-Status: No, score=-1.996 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, FROM_EXCESS_BASE64=0.001, HTML_MESSAGE=0.001, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, UNPARSEABLE_RELAY=0.001, URIBL_BLOCKED=0.001] 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 p4lEgT12fUcH; Wed, 11 Sep 2019 19:38:32 -0700 (PDT)
Received: from ( []) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by (Postfix) with ESMTPS id 4A187120013; Wed, 11 Sep 2019 19:38:30 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;; s=default; t=1568255908; h=Date:From:To:Message-ID:Subject:MIME-Version:Content-Type; bh=jQOL3kOwYxLS2/43oGoXdmOyihls+yCZbS4GmdMyZ/w=; b=fbMm2bWCzlNMAObzp8J+BdikTADioq/n0FJyebD+TU1bs7GgMsl0Pz/erFnCWiPZAwr/qvNarLiqFosmKFzKlPERDeX8i98rF9u2RZAh7kZ4NKaVBjpVPOoNktjZC9lJgK0V60/QlZAjTCxrjbeQJC4BJckNQOKGDLmaRGbsEkU=
X-Alimail-AntiSpam: AC=PASS; BC=-1|-1; BR=01201311R171e4; CH=green; DM=||false|; FP=0|-1|-1|-1|0|-1|-1|-1; HT=e01l07391;; NM=1; PH=DW; RN=6; SR=0; TI=W4_5657687_v5ForWebDing_0AB100A3_1568253704814_o7001c33g;
Received: from WS-web ([W4_5657687_v5ForWebDing_0AB100A3_1568253704814_o7001c33g]) by e01l10437.eu6 at Thu, 12 Sep 2019 10:33:05 +0800
Date: Thu, 12 Sep 2019 10:33:05 +0800
From: "=?UTF-8?B?5b6Q5bCP6JmOKOS5ieWFiCk=?=" <>
To: "Lsr" <>, "=?UTF-8?B?QWNlZSBMaW5kZW0gKGFjZWUp?=" <>, "" <>
Cc: "" <>, "" <>, "" <>
Reply-To: "=?UTF-8?B?5b6Q5bCP6JmOKOS5ieWFiCk=?=" <>
Message-ID: <>
X-Mailer: [Alimail-Mailagent][W4_5657687][v5ForWebDing][Safari]
MIME-Version: 1.0
References: <> <> <>, <>
x-aliyun-mail-creator: W4_5657687_v5ForWebDing_NjATW96aWxsYS81LjAgKE1hY2ludG9zaDsgSW50ZWwgTWFjIE9TIFggMTBfMTJfNikgQXBwbGVXZWJLaXQvNjA1LjEuMTUgKEtIVE1MLCBsaWtlIEdlY2tvKSBWZXJzaW9uLzEyLjAuMyBTYWZhcmkvNjA1LjEuMTU=XQ
In-Reply-To: <>
Content-Type: multipart/alternative; boundary="----=ALIBOUNDARY_13562_4fdf3940_5d79ae61_1d479f2"
Archived-At: <>
Subject: Re: [mpls] =?utf-8?q?=5BLsr=5D_Working_Group_Last_Call_for_=22Signal?= =?utf-8?q?ing_Entropy_Label_Capability_and_Entropy_Readable_Label-stack_D?= =?utf-8?q?epth_Using_OSPF=22_-_draft-ietf-ospf-mpls-elc-08?=
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Multi-Protocol Label Switching WG <>
List-Unsubscribe: <>, <>
List-Archive: <>
List-Post: <>
List-Help: <>
List-Subscribe: <>, <>
X-List-Received-Date: Thu, 12 Sep 2019 02:38:34 -0000

Hi Uma,

The ELC is used to indicate whether an LSR is capable of recognizing and popping the EL associated with the LSP which is terminated on that LSR while the E of the ERLC is used to indicate whether an LSR could perform EL-based load-balancing. In a word, ERLD<>RLD+ELC.

Best regards,

From:Uma Chunduri <>;
Send Time:2019年9月12日(星期四) 07:28
To:Acee Lindem (acee) <>;; <>; <>;; <>;; <>;
Subject:Re: [Lsr] Working Group Last Call for "Signaling Entropy Label Capability and Entropy Readable Label-stack Depth Using OSPF" - draft-ietf-ospf-mpls-elc-08

>Because the intra-area link topology is not exposed across areas or to other protocols. 

Agreed Acee.

But just looking this again then:
Not really clear why ELC is required in Section 4, when it’s confirmed from Stephane’s email (Sept 4th 2019) ERLD covers both reading + doing and action.
Section 4 extending RFC 7794, with E bit, which is defined for prefix attributes for inter-area purposes (no  ERLD value obviously). Same thing can be achieved simply if router capability with ERLD value itself is propagated (per RFC 7981). 

Overall, I am more confused here than earlier. But feel free to ignore my comments.

Uma C.