[mpls] [Technical Errata Reported] RFC5036 (4512)

RFC Errata System <rfc-editor@rfc-editor.org> Mon, 26 October 2015 10:11 UTC

To: loa@pi.se, ina@juniper.net, rhthomas@cisco.com, akatlas@gmail.com, db3546@att.com, aretana@cisco.com, loa@pi.nu, swallow@cisco.com, rcallon@juniper.net
From: RFC Errata System <rfc-editor@rfc-editor.org>
Message-Id: <20151026101114.1E98A18046B@rfc-editor.org>
Date: Mon, 26 Oct 2015 03:11:14 -0700
Archived-At: <http://mailarchive.ietf.org/arch/msg/mpls/yZhGJqtKcFX_BkhrgSFhI6DfCrU>
Cc: mpls@ietf.org, rfc-editor@rfc-editor.org, jiessie.xu@ericsson.com
Subject: [mpls] [Technical Errata Reported] RFC5036 (4512)
Precedence: list

The following errata report has been submitted for RFC5036,
"LDP Specification".

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You may review the report below and at:
http://www.rfc-editor.org/errata_search.php?rfc=5036&eid=4512

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Type: Technical
Reported by: Jiessie <jiessie.xu@ericsson.com>

Section: 2.5.2

Original Text
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2.4.1. Basic Discovery Mechanism

To engage in LDP Basic Discovery on an interface, an LSR periodically
sends LDP Link Hellos out the interface. LDP Link Hellos are sent as
UDP packets addressed to the well-known LDP discovery port for the
\\"all routers on this subnet\\" group multicast address.

2.5.2. Transport Connection Establishment

Note that when an LSR sends a Hello, it selects the transport address
for its end of the session connection and uses the Hello to advertise
the address, either explicitly by including it in an optional
Transport Address TLV or implicitly by omitting the TLV and using it
as the Hello source address.

Corrected Text
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Notes
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According to 2.4.1, an LSR send Hellos to \\"all routers on this subnet\\", the eligible reception LSR should be on this subnet.

2.5.2 states that one way for an LSR to advertise Transport Address is to uses it as Hello source address.

On the topology below, LSRa uses 1.1.1.1 as Transport Address and sends Hello(source:1.1.1.1 destination:224.0.0.2) to LSRb.
LSRb will ignore this packet which is not on its interface subnet.

1.1.1.1
|LSRa|--------------|LSRb|
10.1.1.1 10.1.1.2

My question is:
What\\'s the scenario to use \\"implicitly\\" way to send Hello?

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RFC5036 (draft-ietf-mpls-rfc3036bis-04)
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Title : LDP Specification
Publication Date : October 2007
Author(s) : L. Andersson, Ed., I. Minei, Ed., B. Thomas, Ed.
Category : DRAFT STANDARD
Source : Multiprotocol Label Switching
Area : Routing
Stream : IETF
Verifying Party : IESG

[mpls] [Technical Errata Reported] RFC5036 (4512) RFC Errata System
Re: [mpls] [Technical Errata Reported] RFC5036 (4… Renato Westphal
[mpls] [Errata Rejected] RFC5036 (4512) RFC Errata System