Subject: Re: [mpls-tp] a question about draft-cheung-mpls-tp-mesh-protection-01

From: "Taesik Cheung" <[email-masked]>
Date: Fri, 30 Jul 2010 17:45:23 +0900

Hi Liu,

Thank you for the comments.

Please see in-line.

Regards,

Taesik

-----Original Message-----
From: "[email-masked]" <[email-masked]>
From Date: 2010-07-30 PM 5:06:30
To: "[email-masked]" <[email-masked]>, "[email-masked]" <[email-masked]>
Cc: "[email-masked]" <[email-masked]>, "[email-masked]" <[email-masked]>
Subject: a question about draft-cheung-mpls-tp-mesh-protection-01

hi,
today I reviewed your this draft, I have a few questions for mesh protection
1 in section 3, In my mind, there is a sentence : In both cases, 1:1 or 1+1 protection may be used.
if there use 1+1 protection for each working path. it is no necessary to apply mesh protection.
beacause the bandwidth resource of protection is equal to the sum of bandwidth resource of all
protected path. so I think 1+1 protection should not be used in the mesh protection.
do you think so?

[Taesik] Yes, if 1+1 protection is used, shared mesh protection is not necessary. The sentence is just generic one. Right after the sentence, we described that if 1:1 protection is used, the segment PQR can be shared by two protection paths.

2 about the Shared node SEN will send the protection locking message requesting
LoP to the end node of protected LSP. IMO, as SEN node is MIP of the protected
LSP , it can't generate unsolicit OAM packet to send other node. so how to generate
the protection locking message requesting LOP in the SEN node ?

[Taesik] The protection locking message is a response to the protection state change notification message sent from a MEP. It is similar to LTM/LTR or Lock Intruct / Lock Report relationship.

Maybe i miss something important?
thank you

best regards
liu

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---

From: [email-masked]
Date: Fri, 30 Jul 2010 17:21:08 +0800

Taesik
thank you for replying .but I don't agree your opinions
According to your describles in the draft. I think the protection locking 
message isn't  a response to the protection state change notification 
message sent from a MEP.
and it is activley generate a Locking Request message for the SEN node.
for example. the following figure : 
          A------B------C  D------E------F 
            \   LPD1   /        \   LPD3  / 
              \            /            \            / 
               P-----Q----------R-----S 
              /                                   \ 
             /           LPD2                \ 
            /                                        \ 
           G--------------H---------------J 
a. Node G detects the failure, and initiates the linear protection 
      switching for the failed working path G-H-J;

   b. At the same time, node G generates the protection switching event 
      message saying that a protection switching event happened to node 
      P and R, which are SENs for J->H->G.

   c. The SEN P compares the protection switching priority of LPD2 with 
      that of LPD1. In this example, as the priority of LPD1 is higher 
      than LPD2, SEN P does not take an action to node A.
      The SEN R compares the protection switching priority of LPD2 with 
      that of LPD3. In this example, as the priority of LPD3 is lower 
      than LPD2, SEN R sends the protection locking message requesting 
      LoP to node D.(if the Locking message is a response to the 
protection 
      state change , I think the Locking message should send to Node G ,
      not node D. because at the time there is no protection state change 
for LPD2 .
     Node D can't send any state change request to SEN node R firstly.
     do you think so?  )

   d. Node D takes the protection locking message as an input to the 
      linear protection switching, and follows the linear protection 
      switching procedure to process the end-to-end LoP command 

 maybe my understanding be wrong?

  best regards
   liu 

"Taesik Cheung" <[email-masked]> 
发件人:  [email-masked]
2010-07-30 16:45
请答复 给
Taesik Cheung <[email-masked]>

收件人
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Re: [mpls] a question about draft-cheung-mpls-tp-mesh-protection-01

Hi Liu,

Regards,
Taesik

-----Original Message-----
From: "[email-masked]" <[email-masked]>
From Date: 2010-07-30 PM 5:06:30
To: "[email-masked]" <[email-masked]>, "[email-masked]" <[email-masked]>
Cc: "[email-masked]" <[email-masked]>, "[email-masked]" <[email-masked]>
Subject: a question about draft-cheung-mpls-tp-mesh-protection-01

 hi, 
 today I reviewed your this draft, I have a few questions for mesh 
protection 
 1 in section 3, In my mind, there is a sentence : In both cases, 1:1 or 
1+1 protection may be used. 
   if there use 1+1 protection for each working path. it is no necessary 
to apply mesh protection. 
   beacause the bandwidth resource of protection is equal to the sum of 
bandwidth resource of all 
   protected path. so I think 1+1 protection should not be used in the 
mesh protection. 
   do you think so? 
[Taesik] Yes, if 1+1 protection is used, shared mesh protection is not 
necessary. The sentence is just generic one. Right after the sentence, we 
described that if 1:1 protection is used, the segment PQR can be shared by 
two protection paths.

 2 about the Shared node SEN will send the protection locking message 
requesting 
      LoP to the end node of protected LSP. IMO, as SEN node is MIP of the 
protected 
      LSP , it can't generate unsolicit OAM packet to send other node. so 
how to generate 
    the protection locking message requesting LOP in the SEN node ? 
[Taesik] The protection locking message is a response to the protection 
state change notification message sent from a MEP. It is similar to 
LTM/LTR or Lock Intruct / Lock Report relationship.

  best regards 
  liu 

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solely for the use of the individual or entity to whom they are addressed. 
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