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) " <xiaohu.xxh@alibaba-inc.com> Thu, 12 September 2019 02:38 UTC

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Date: Thu, 12 Sep 2019 10:33:05 +0800
From: "=?UTF-8?B?5b6Q5bCP6JmOKOS5ieWFiCk=?=" <xiaohu.xxh@alibaba-inc.com>
To: "Lsr" <lsr-bounces@ietf.org>, "=?UTF-8?B?QWNlZSBMaW5kZW0gKGFjZWUp?=" <acee@cisco.com>, "lsr@ietf.org" <lsr@ietf.org>
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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?=
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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,
Xiaohu






------------------------------------------------------------------
From:Uma Chunduri <uma.chunduri@futurewei.com>;
Send Time:2019年9月12日(星期四) 07:28
To:Acee Lindem (acee) <acee@cisco.com>;; lsr@ietf.org <lsr@ietf.org>;
Cc:mpls@ietf.org <mpls@ietf.org>;; lsr-ads@ietf.org <lsr-ads@ietf.org>;; draft-ietf-ospf-mpls-elc@ietf.org <draft-ietf-ospf-mpls-elc@ietf.org>;
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.