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RE: [PWE3] PWE3 question

To: "'Shahram Davari'" <Shahram_Davari@pmc-sierra.com>
Subject: RE: [PWE3] PWE3 question
From: Sasha Vainshtein <Sasha@AXERRA.com>
Date: Fri, 10 May 2002 08:56:57 +0200
Cc: "'pwe3@ietf.org'" <pwe3@ietf.org>, "Danny McPherson (E-mail)" <danny@tcb.net>, "'Andrew G. Malis'" <Andy.Malis@VivaceNetworks.com>, "Neil. 2. Harrison (E-mail)" <neil.2.harrison@bt.com>
List-Id: Pseudo Wires Edge to Edge <pwe3.ietf.org>
Sender: pwe3-admin@ietf.org
Shahram and all.
Please see a brief comment inline.

----------------------------------------------------------------------------
--------
With best regards,
                          Sasha Vainshtein
email:   sasha@axerra.com <mailto:sasha@axerra.com> 
phone:  +972-3-7659993 (office)
            +972-8-9254948 (home)
            +972-58-674833 (cellular)


> -----Original Message-----
> From: Shahram Davari [mailto:Shahram_Davari@pmc-sierra.com]
> Sent: Thursday, May 09, 2002 10:59 PM
> To: 'Sasha Vainshtein'; 'Andrew G. Malis'
> Cc: 'pwe3@ietf.org'; Danny McPherson (E-mail)
> Subject: RE: [PWE3] PWE3 question
> 
> 
> Sasha,
> 
> > -----Original Message-----
> > From: Sasha Vainshtein [mailto:Sasha@AXERRA.com]
> > Sent: Thursday, May 09, 2002 5:45 PM
> > To: Shahram Davari; Sasha Vainshtein; 'Andrew G. Malis'
> > Cc: 'pwe3@ietf.org'; Danny McPherson (E-mail)
> > Subject: RE: [PWE3] PWE3 question
> > 
> > 
> > Shahram,
> > I agree that it is possible to force the routers in
> > the PSN to allocate a label per a VC FEC without
> > understanding it.
> > However I donot agree that this does not mean
> > exerting control over the network - and this should
> > not be done in PWE3.
> 
> In what respect do you see this exerting control over the
> PSN network? In contrast I don't see any.
> 
> > Once more, I donot say that what you propose cannot be 
> > done - I just claim that this is beyound the scope defined
> > by the PWE3 chapter.
> 
> Since the PSN interior nodes need not know anything about the
> PW, I think this actually falls within PWE3 charter.
>

I would suggest a very simple criterion regarding exertion or
non-exertion of control over PSN: if setup/teradown of a PW
requires modification of the FIB in at least one PSN node that 
does not act as the PE for this PW, it means that control over 
this router has been exerted. 

This criterion does not depend on the protocol being used
(static,LDP, RSVP or else).

The single-label model requires allocation of a new label per PW
in each interior node on the path fromingress to egress, and hence
means exertion of control over the PSN unless the the pair of
PEs are adjacent (the "single hop" case mentioned by Neil).

Can we agree on that?

> 
> -Shahram
> 
> > 
> > --------------------------------------------------------------
> > --------------
> > --------
> > With best regards,
> >                           Sasha Vainshtein
> > email:   sasha@axerra.com <mailto:sasha@axerra.com> 
> > phone:  +972-3-7659993 (office)
> >             +972-8-9254948 (home)
> >             +972-58-674833 (cellular)
> > 
> > 
> > > -----Original Message-----
> > > From: Shahram Davari [mailto:Shahram_Davari@pmc-sierra.com]
> > > Sent: Thursday, May 09, 2002 5:31 PM
> > > To: 'Sasha Vainshtein'; 'Andrew G. Malis'
> > > Cc: 'pwe3@ietf.org'; Danny McPherson (E-mail)
> > > Subject: RE: [PWE3] PWE3 question
> > > 
> > > 
> > > Sasha,
> > > 
> > > LSP ID is used to make sure that CR-LDP never advertises
> > > the same label to two different requests.
> > > 
> > > And M-bit=0 (merge bit) could be used in RSVP-TE to make sure
> > > that no merging occurs.
> > > 
> > > -Shahram
> > > 
> > > > -----Original Message-----
> > > > From: Sasha Vainshtein [mailto:Sasha@AXERRA.com]
> > > > Sent: Thursday, May 09, 2002 12:06 PM
> > > > To: Shahram Davari; Sasha Vainshtein; 'Andrew G. Malis'
> > > > Cc: 'pwe3@ietf.org'; Danny McPherson (E-mail)
> > > > Subject: RE: [PWE3] PWE3 question
> > > > 
> > > > 
> > > > Shahram,
> > > > I am confused.
> > > > If the intermediate routers recognize only ERO 
> > > > what would prevent them from advertizing upstream the same 
> > > label for 
> > > > all the PWs along the same path? 
> > > > IMHO both PEs needs a unique label per PW (in one direction);
> > > > I do not understand how this can be achieved if the intermediate
> > > > routers do not recognize different VC FECs.
> > > > 
> > > > With best regards,
> > > >                                    Sasha Vainshtein
> > > > email:     sasha@axerra.com <mailto:sasha@axerra.com> 
> > > > tel:       +972-3-7659993 (office)
> > > >            +972-8-9254948 (res.)
> > > >            +972-58-674833 (cell.)
> > > >  
> > > > 
> > > > 
> > > > > -----Original Message-----
> > > > > From: Shahram Davari [mailto:Shahram_Davari@pmc-sierra.com]
> > > > > Sent: Thursday, May 09, 2002 2:57 PM
> > > > > To: 'Sasha Vainshtein'; 'Andrew G. Malis'
> > > > > Cc: 'pwe3@ietf.org'; Danny McPherson (E-mail)
> > > > > Subject: RE: [PWE3] PWE3 question
> > > > > 
> > > > > 
> > > > > Sasha,
> > > > > 
> > > > > ER-LSPs work by DoD label assignment. And the ERO 
> > > > identifies the path.
> > > > > VC FEC is not needed to be processed in the intermediate 
> > > > LSRs at all.
> > > > > 
> > > > > -Shahram
> > > > > 
> > > > > > -----Original Message-----
> > > > > > From: Sasha Vainshtein [mailto:Sasha@AXERRA.com]
> > > > > > Sent: Thursday, May 09, 2002 2:58 AM
> > > > > > To: Shahram Davari; 'Andrew G. Malis'
> > > > > > Cc: 'pwe3@ietf.org'; Danny McPherson (E-mail)
> > > > > > Subject: RE: [PWE3] PWE3 question
> > > > > > 
> > > > > > 
> > > > > > Shahram,
> > > > > > 
> > > > > > IMHO, if you use only one label for a PW, it is this 
> > label that
> > > > > > is switched through the path from ingress to egress. 
> > > > > > Aand if the routesr do not recognize the VC FEC, how should
> > > > > > they assign and switch labels associated with this FEC?
> > > > > > 
> > > > > > With best regards,
> > > > > >                                    Sasha Vainshtein
> > > > > > email:     sasha@axerra.com <mailto:sasha@axerra.com> 
> > > > > > tel:       +972-3-7659993 (office)
> > > > > >            +972-8-9254948 (res.)
> > > > > >            +972-58-674833 (cell.)
> > > > > >  
> > > > > > 
> > > > > > 
> > > > > > > -----Original Message-----
> > > > > > > From: Shahram Davari 
> [mailto:Shahram_Davari@pmc-sierra.com]
> > > > > > > Sent: Wednesday, May 08, 2002 9:05 PM
> > > > > > > To: 'Sasha Vainshtein'; 'Andrew G. Malis'
> > > > > > > Cc: 'pwe3@ietf.org'; Danny McPherson (E-mail)
> > > > > > > Subject: RE: [PWE3] PWE3 question
> > > > > > > 
> > > > > > > 
> > > > > > > Sasha,
> > > > > > > 
> > > > > > > I don't think in this case all the routers in the PSN
> > > > > > > need to recognize the VC FEC.  You could set the 
> > U/F bits to 1
> > > > > > > in VC FEC, therefore no need for the interior routers to
> > > > > > > recognize the VC FEC.
> > > > > > > 
> > > > > > > 
> > > > > > > -Shahram
> > > > > > > 
> > > > > > > 
> > > > > > > 
> > > > > > > > -----Original Message-----
> > > > > > > > From: Sasha Vainshtein [mailto:Sasha@AXERRA.com]
> > > > > > > > Sent: Wednesday, May 08, 2002 1:59 PM
> > > > > > > > To: 'Andrew G. Malis'; Shahram Davari
> > > > > > > > Cc: 'pwe3@ietf.org'; Danny McPherson (E-mail)
> > > > > > > > Subject: RE: [PWE3] PWE3 question
> > > > > > > > 
> > > > > > > > 
> > > > > > > > Andy and Shahram,
> > > > > > > > 
> > > > > > > > IMHO using only one label would, regardless
> > > > > > > > of the other issues, violate one of the requirements
> > > > > > > >  of the PWE3 Charter:
> > > > > > > > 
> > > > > > > > <quote>
> > > > > > > > PWE3 will not exert controls on the underlying PSN,
> > > > > > > > but only function at the endpoints of the pseudo wire, 
> > > > > > > > though the endpoints may be configured to set diffserv 
> > > > > > > > codepoints in the tunneling datagrams. 
> > > > > > > > <end quote>
> > > > > > > > 
> > > > > > > > Building an explicit TE tunnel for a single PW 
> > means to me 
> > > > > > > > exerting a control over the PSN (e.g., all the routers 
> > > > > in the PSN
> > > > > > > > should recognize VC FECs etc.).
> > > > > > > > 
> > > > > > > > In other words, it probably can be done, but it would 
> > > > > not be PWE3.
> > > > > > > > 
> > > > > > > > With best regards,
> > > > > > > >                                    Sasha Vainshtein
> > > > > > > > email:     sasha@axerra.com <mailto:sasha@axerra.com> 
> > > > > > > > tel:       +972-3-7659993 (office)
> > > > > > > >            +972-8-9254948 (res.)
> > > > > > > >            +972-58-674833 (cell.)
> > > > > > > >  
> > > > > > > > 
> > > > > > > > 
> > > > > > > > > -----Original Message-----
> > > > > > > > > From: Andrew G. Malis 
> > > [mailto:Andy.Malis@VivaceNetworks.com]
> > > > > > > > > Sent: Wednesday, May 08, 2002 5:51 PM
> > > > > > > > > To: Shahram Davari
> > > > > > > > > Cc: 'Andrew G. Malis'; 'pwe3@ietf.org'
> > > > > > > > > Subject: RE: [PWE3] PWE3 question
> > > > > > > > > 
> > > > > > > > > 
> > > > > > > > > Shahram,
> > > > > > > > > 
> > > > > > > > > Yeah, you would have to treat each VC as a 
> separate TE 
> > > > > > > > tunnel and use 
> > > > > > > > > either RSVP-TE or CR-LDP for signaling 
> > (suitably extended 
> > > > > > > > > along Martini 
> > > > > > > > > lines for VC type and ID).
> > > > > > > > > 
> > > > > > > > > Cheers,
> > > > > > > > > Andy
> > > > > > > > > 
> > > > > > > > > -------
> > > > > > > > > 
> > > > > > > > > At 5/8/2002 08:33 AM -0700, Shahram Davari wrote:
> > > > > > > > > >Andy,
> > > > > > > > > >
> > > > > > > > > >Sure I understand the scaling issue. But 
> ignoring the 
> > > > > > > scalability,
> > > > > > > > > >I want to know if it can be done and if so how?
> > > > > > > > > >
> > > > > > > > > >It seems that you may not be able to use LDP 
> any more, 
> > > > > > > > because VC FEC
> > > > > > > > > >is meaningless to the interior LSRs. But it 
> > > seems that you 
> > > > > > > > could use
> > > > > > > > > >ER-LSPs and therefore do TE. Right?
> > > > > > > > > >
> > > > > > > > > >Yours,
> > > > > > > > > >-Shahram
> > > > > > > > > >
> > > > > > > > > >
> > > > > > > > > > > -----Original Message-----
> > > > > > > > > > > From: Andrew G. Malis 
> > > > [mailto:Andy.Malis@vivacenetworks.com]
> > > > > > > > > > Sent: Tuesday, May 07, 2002 6:12 PM
> > > > > > > > > > To: Shahram Davari
> > > > > > > > > > Cc: 'pwe3@ietf.org'
> > > > > > > > > > Subject: Re: [PWE3] PWE3 question
> > > > > > > > > >
> > > > > > > > > >
> > > > > > > > > > Shahram,
> > > > > > > > > >
> > > > > > > > > > Well, it wouldn't scale very well since every 
> > > switch along
> > > > > > > > > > the path is
> > > > > > > > > > involved in the signaling for each VC, and 
> you can't 
> > > > > > do traffic
> > > > > > > > > > engineering, so I would say that's pretty much a 
> > > > > non-starter.
> > > > > > > > > >
> > > > > > > > > > Cheers,
> > > > > > > > > > Andy
> > > > > > > > > >
> > > > > > > > > > At 5/7/2002 12:02 PM -0700, Shahram Davari wrote:
> > > > > > > > > > >Hi,
> > > > > > > > > > >
> > > > > > > > > > >Can we implement PWE3 with only one label 
> > (i.e., only 
> > > > > > > VC label)?
> > > > > > > > > > >
> > > > > > > > > > >-Shahram
> > > > > > > > > > >
> > > > > > > > > > >_______________________________________________
> > > > > > > > > > >pwe3 mailing list
> > > > > > > > > > >pwe3@ietf.org
> > > > > > > > > > >https://www1.ietf.org/mailman/listinfo/pwe3
> > > > > > > > > >
> > > > > > > > 
> > > > > > > > 
> > > > > > > > _______________________________________________
> > > > > > > > pwe3 mailing list
> > > > > > > > pwe3@ietf.org
> > > > > > > > https://www1.ietf.org/mailman/listinfo/pwe3
> > > > > > > > 
> > > > > > > 
> > > > > > 
> > > > > 
> > > > 
> > > 
> > 
> 

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