答复: RE: Comments on draft-jounay-pwe3-leaf-initiated-p2mp-pw-01

[zhang.xinquan at zte.com.cn]

Hi Frederic, 

Thanks for your clarificaton.

You have two drafts about P2MP PW signaling,
one is leaf-initiated mode and the other is source-initiated mode. In my
opinion, your original intention is to propose leaf-initiated mode as a
solution for inter-domain scenario, and source-initiated mode for intra-domain
scenario. Am I right? Or your have other considerations?

Best regards!

Xinquan Zhang

2009/4/21

<frederic.jounay at orange-ftgroup.com>
发件人:  l2vpn-bounces at ietf.org

2009-04-20 20:55

收件人	<zhang.xinquan at zte.com.cn>
抄送	l2vpn at ietf.org, l2vpn-bounces at ietf.org, pwe3 at ietf.org
主题	RE: Comments on draft-jounay-pwe3-leaf-initiated-p2mp-pw-01

Hi Xinquan,
 
Please see my answer inline [FJ]
 
Best Regards,
Fred

---

De : zhang.xinquan at zte.com.cn [mailto:zhang.xinquan at zte.com.cn]
Envoyé : mercredi 15 avril 2009 07:50
À : JOUNAY Frederic RD-RESA-LAN
Cc : l2vpn at ietf.org; l2vpn-bounces at ietf.org
Objet : Comments on draft-jounay-pwe3-leaf-initiated-p2mp-pw-01


Hi, Frederic, 

I have read draft-jounay-pwe3-leaf-initiated-p2mp-pw-01 and have some comments.
please see below: 

1、section 5.4. Configuration 
    
   After configuring on each T-PE the attached AIIs, it is assumed
that 
   all the PEs (Ingress/Egress T-PEs and all S-PEs) maintain an AII
PW 
   routing table which gives for each AII as entry the "next
hop" to 
   reach that AII. This AII routing table can be filled manually or
   updated dynamically by means of some extended routing protocol
like 
   proposed in [DYN MS-PW]. The construction of the table is out of
   scope of the present document. 
    
   Each PE relies on its AII PW routing table to select the next hop
PE 
   (S-PE or T-PE) to reach a given AII. 

>1  Does this AII routing table include both TAII and SAII?

[FJ] Yes, the AII routing table
dynamically populated (BGP, OSPF, IS-IS or LDP) should maintain both. The
Egress T-PE joins the PW tree by initiating a Label Map whose the FEC contains
the SAII, the PW tree source. Hence upon receipt of the message the S-PE
does a lookup to select the NH to reach this SAII.    
 
>2  In S-PE, this AII routing table includes all the AII, or just
part of the AII( e.g. which are in its dowstream)?
 [FJ] the AII routing table should be used also for VPWS or VPLS, so bidirectional
PW. Therefore the AII routing table must reflect all the AII configured
on T-PEs. Of course agregate AII format (i.e. w/o ACID info) as defined
in [DYN MS-PW] must be used to optimize the AII routing table

2、Section 5.7. Using TAII Leaf Sub-TLV 
    
   Section TBD 
    
   The TAII Leaf sub-TLV MAY be optionally used when a leaf joins
the PW 
   tree to announce to the source that it is part from the PW tree.
If 
   this option is chosen, the Egress T-PE adds to the FEC Element
this 
   TAII sub-TLV in the Label Map message. As soon as in the source
   direction a Label Map is not required since for instance a S-PE
   already maintains a state for this MS-PW tree, the information
   related to the Leaf TAIIs is retrieved from the TAII Leaf sub-TLV
and 
   is propagated by means of a LDP Notification message up to the
   corresponding Ingress T-PE.   
> I am not sure about the propagation of TAII Leaf sub-TLV. Is it sent
to ingress T-PE directly, or to the upstream S-PE(if there exists such
S-PE in the upstream direction)?  
[FJ] The Notification message
can not be directly sent to the Ingress T-PE if there is not direct T-LDP
session to reach the Ingress T-PE, i.e. S-PE in between. That's the reason
why the message should be propagated hop by hop (i.e. S-PE by S-PE)
up to the Ingress T-PE.
 I agree with you that's
worth clarifying this section. 

Best Regards! 

Xinquan Zhang 

2009/4/15