Re: [mpls] working group last call on draft-ietf-mpls-tp-li-lb-01.txt

sami, yaccov,hi
firstly i say sorry for not clearly describling my question. 
for the first question, maybe yaacov's understanding be right. if a mep is 

on loopback state, it can't check the e2e path for mis-connectivity 
because
the mep point loopback everything including any OAM packet(cc&cv etc);

for the second question, I know loss/delay measurement should use LM/DM 
fuction to 
implement it. but for loopback function, there are the following two 
application:
  1 To verify bidirectional connectivity of a MEP with a MIP or a peer MEP
;
  2 To perform a bidirectional in-service or out-of-service diagnostics 
test between a pair of peer MEPs. This includes verifying bandwidth 
throughput, detecting bit errors, etc;

so for application 1, loopback anything will not affect verify 
bidirectional connectivity; but it may affect diagnostics test.
for example, if mis-connectivity or mis-configuration happened on a LSP 
path, since the mep of the lsp is under loopback state, it can't check 
mis-connectivity,
so the mep of the lsp maybe loopback other data packet of another lsp to 
the peer mep.or the data pkt of the LSP will be leaked to other LSP path, 
so it must affect the result of diagnostics test including bandwidth 
throughput, bit errors.

maybe i miss something important?

thank sami and yaacov for prompt replying it.

B.R.
Liu

Sami Boutros <sboutros@cisco.com> 
2011-05-13 05:05

收件人
"Weingarten, Yaacov (NSN - IL/Hod HaSharon)" <yaacov.weingarten@nsn.com>, 
<liu.guoman@zte.com.cn>, "Loa Andersson" <loa@pi.nu>
抄送
"Ross Callon" <rcallon@juniper.net>, <mpls@ietf.org>, "MPLS-TP ad hoc 
team" <ahmpls-tp@lists.itu.int>, <draft-ietf-mpls-tp-li-lb@tools.ietf.org>
主题
RE: [mpls] working group last call on  draft-ietf-mpls-tp-li-lb-01.txt

Agreed Yaacov, during the period of loopback the cc-cv function can't be 
performed, and yes the main benefit is of loopback is to measure 
loss/delay on a segment of a path as you stated.

Thanks,

Sami
At 10:36 PM 5/11/2011, Weingarten, Yaacov (NSN - IL/Hod HaSharon) wrote:
Sami, hi

My understanding is that the question that was asked is how do you use the 
cc-cv function to check for mis-connectivity if it is being looped-back.

Truth be told that during the period of loopback you apparently cannot 
check the e2e path for mis-connectivity, and the operator needs to take 
this into consideration.  But since the path is not transferring data e2e 
(it is looping everything back) it is by definition not connected e2e.

What is true is what Sami states this functionality should be used to 
setup a loss/delay measurement on a segment of a path, and it should be 
used only for limited periods.

Just my 2cents,
yaacov

From: mpls-bounces@ietf.org [ mailto:mpls-bounces@ietf.org] On Behalf Of 
ext Sami Boutros
Sent: Thursday, May 12, 2011 8:03 AM
To: liu.guoman@zte.com.cn; Loa Andersson
Cc: Ross Callon; mpls@ietf.org; MPLS-TP ad hoc team; 
draft-ietf-mpls-tp-li-lb@tools.ietf.org
Subject: Re: [mpls] working group last call on 
draft-ietf-mpls-tp-li-lb-01.txt

To check for mis-connectivity/mis-configuration, you need a cc-cv function 
not a loopback function.

The loopback function can be used for loss/delay measurements, and this 
will be addressed in the delay/loss draft.

Thanks,

Sami
At 07:11 PM 5/10/2011, liu.guoman@zte.com.cn wrote:

hi, all 
for this draft, I have a question for Loopback function. 
in last ietf meeting, IMO, the author sami said this 
Loopback function is to loopback anything. for MEP point of 
a LSP, if it is set to Loopback state, it will loopback all received 
packets including any OAM packet. if so, how to detect mis-connectivity or 

mis-configuration for the LSP? 
in addtion, if it happen mis-connectivity, maybe other LSP packet be 
transported to 
the MEP , and the mep point will still Loopback the wrong packet to peer 
mep point, 
can it affect performance statistics or measurement on the peer mep point? 

B.R. 
liu 

Loa Andersson <loa@pi.nu> 
·¢¼þÈË:  mpls-bounces@ietf.org 

2011-05-10 23:43 
ÊÕ¼þÈË
"mpls@ietf.org" <mpls@ietf.org> 
³ËÍ
Ross Callon <rcallon@juniper.net>, MPLS-TP ad hoc team 
<ahmpls-tp@lists.itu.int>, draft-ietf-mpls-tp-li-lb@tools.ietf.org 
Ö÷Ìâ
[mpls] working group last call on draft-ietf-mpls-tp-li-lb-01.txt 

Working Group,

this is to start a two week working group last call on

draft-ietf-mpls-tp-li-lb-01.txt

Please send your comments to the mpls@ietf.org mailing list.

This working group last call ends on May 25th.

/Loa

for the mpls wg co-chairs

-- 

Loa Andersson                         email: loa.andersson@ericsson.com
Sr Strategy and Standards Manager            loa@pi.nu
Ericsson Inc                          phone: +46 10 717 52 13
                                             +46 767 72 92 13
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