Subject: [mpls] [Errata Rejected] RFC5036 (4512)

From: RFC Errata System <[email-masked]>
Date: Wed, 18 Nov 2015 10:54:39 -0800 (PST)

The following errata report has been rejected 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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Status: Rejected
Type: Technical

Reported by: Jiessie <[email-masked]>
Date Reported: 2015-10-26
Rejected by: Deborah Brungard (IESG)

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?
 --VERIFIER NOTES-- 
   This is not an errata, it is a question to be asked on the MPLS mailing list.

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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