RE: Static VPLS MAC withdrawal draft

[Alexander Vainshtein <[e-mail]>]

Resending with less addressees...

Regards,
     Sasha


> -----Original Message-----
> From: Alexander Vainshtein
> Sent: Thursday, May 10, 2012 5:08 PM
> To: '[e-mail]:'; Sami Boutros ([e-mail]);
> '[e-mail]'
> Cc: [e-mail]; 'Giles Heron'; Rotem Cohen; Andrew Sergeev; Mishael
> Wexler; Gideon Agmon
> Subject: RE: Static VPLS MAC withdrawal draft
> 
> Hi all,
> I've read the draft in question and I would like to clarify several issues that
> look either undefined or ambiguous to me.
> 
> 1. To the best of my understanding, the draft requires each PE participating
> in a given VPLS instance to set up two counters for each static PW
> connecting it to a peer PE device in this VPLS instance: one for static MAC
> withdrawal messages it is going to send and another - for static MAC
> withdrawal messages it receives. Is this understanding correct?
> 
> 2. Assuming a positive answer to the previous questions, how are these
> counters initialized? The draft seems to be moot on this point. The more
> interesting question is, of course, about initialization of the counter of
> received static MAC withdrawal messages, since, with static PWs, generally
> speaking, there is no synchronization between setting up one of its end
> points and setting up another one.
> 
> 3. The draft specifies that:
> 	- The transmitter sends the MAC withdrawal message with the same
> sequence number until it receives an ACK for it (Section 4.1.1)
> 	- The receiver, after having acknowledged a MAC withdrawal
> message, ignores refresh messages with the same sequence number
> (Section 4.1.2)
>   What is supposed to happen in the following scenario:
> 	- Transmitter finds out that some MACs have to be withdrawn (e.g.,
> because the AC from which they have been learned fails)
> 	   and sends a MAC withdrawal message to its peers with sequence
> number N
> 	- Immediately after that (i.e., before it receives an ACK for this
> message) it finds out that yet another set of MAC addresses has to be
> withdrawn
> 	- Retransmission timer expires without ACK received.
> 
> 4. Suppose that only one end point of a static PW between a given pair of
> peers has been set up. In this case transmitting the static MAC withdrawal
> messages via such a PW is possible, but ACKs will never be received. Should
> retransmission of these messages go on "ad infinitum"?
> 
> 5. The draft does not specify any default value for the retransmit time.
> 
> 6. A nit:  Heading of Section 4 is followed by headings for Sections 4.1.1 and
> 4.1.2 without any heading for 4.1.
> 
> Hopefully these questions will be useful.
> 
> Regards,
>      Sasha
> 
> > -----Original Message-----
> > From: [e-mail] [mailto:[e-mail]] On Behalf
> > Of Giles Heron
> > Sent: Tuesday, May 08, 2012 10:06 PM
> > To: [e-mail]
> > Subject: Static VPLS MAC withdrawal draft
> >
> > Hi everyone,
> >
> > The following draft was presented at IETF in Paris:
> >
> > http://tools.ietf.org/html/draft-boutros-l2vpn-mpls-tp-mac-wd-00
> >
> > The authors have asked for it to be adopted as a WG draft, but at this stage
> > the chairs' view is that it probably hasn't had enough sets of eyes on it.
> >
> > So this email is to request that those on the list take a read of the draft
> > and send comments back to the list.  Depending on the response we get
> we
> > may
> > then ask the WG if they feel happy adopting this as a WG draft.
> >
> > Nabil and Giles
> >


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