Subject: [MBONED] A few comments on mtrace version 2 draft

From: liu hui <[email-masked]>
Date: Fri, 01 Feb 2008 12:09:48 +0800

Hi the authors and ML, 

I have a few comments on the Mtrace draft, one is functional and the others
are editorial.

Section 9.2 describes there manners of sending Query.  Under the condition
when Query is unicasted to the Destination (i.e. the receiver), if multicast
patFrom [email-masked]  Thu Jan 31 20:08:30 2008
Date: Fri, 01 Feb 2008 12:09:48 +0800
From: liu hui <[email-masked]>
To: 'Hitoshi Asaeda' <[email-masked]>, [email-masked],
	[email-masked], [email-masked]
Cc: [email-masked]
Subject: [MBONED] A few comments on mtrace version 2 draft
Sender: [email-masked]

This is a multi-part message in MIME format.
Hi the authors and ML, 

I have a few comments on the Mtrace draft, one is functional and the others
are editorial.

Section 9.2 describes there manners of sending Query.  Under the condition
when Query is unicasted to the Destination (i.e. the receiver), if multicast
path does not follow the optimal unicast path, the unicast last-hop (LH)
router may possibly be not the multicast LH (e.g.,because of PIM DR
selection). In this case the multicast path could not be traced because when
the Query packet arrives at the unicast LH which has no multicast forwarding
states, the router will give up the tracing by noting a WRONG_LAST_HOP
response to the Querier.

This little defect could be improved through multicasting the Query by the
unicast LH router to the subnet, with the packet's destination address set
to 224.0.0.2. The multicast LH on the subnet picks up this Query and
initiates a Request packet. Then the multicast path can be traced normally
as the draft describes.

Sect. 4.2 the item "# hops" does not appeared in the previous table. If it
is HopLim in the table, it could be explained in 4.8 with "Resp TTL".

Sect. 5.5 "packet counts" also does not appear in the previous table. 

Sect. 8.2.2 There are Repetitious illustrations of REACHED-RP in step 2 and
8, respectively as:

"If this router is the Core or RP and no source-specific information is
available, note an error code of REACHED_RP"

"If this router is the Rendez-vous Point or Core for the group, a forwarding
code of REACHED_RP is noted"

If this is not restated intentionally, only one step should be remained.

Regards,

Liu Hui

 

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