Subject: Re: [PWE3] Corner case status timeout handling in draft-ietf-pwe3-static-pw-status-00.txt

From: [email-masked]
Date: Fri, 11 Jun 2010 23:06:32 +0800

Hi Luca,
I prefer option 2, it is the safest way to keep the status as it was when 
expired.

BR
Lizhong

> -----Original Message-----
> From: pwe3-bounces at ietf.org [mailto:pwe3-bounces at ietf.org] On 
Behalf Of
> Neil McGill
> Sent: Thursday, June 10, 2010 8:56 PM
> To: Luca Martini
> Cc: PWE3 WG (E-mail)
> Subject: Re: [PWE3] Corner case status timeout handling in draft-ietf-
> pwe3-static-pw-status-00.txt
> 
> 
> Standby is not really an error and just happens to share the error
> bitmap, therefore should not really be cleared upon expiration of
> an error condition.
> 
> The peer will eventually clear the standby when it transitions out
> of this state anyway  - but if that all clear message is also lost...
> 
> 1) but preserve the standby bit.
> 
> Thanks,
> 
> Neil.
> 
> 
> 
> On Thu, 10 Jun 2010, Luca Martini wrote:
> 
> > WG,
> >
> > I need some suggestions and a bit of help of the following problem
> that
> > was raised in a private e-mail to me.
> >
> > As defined in the document today, status for static PW is
> retransmitted
> > periodically ( let's assume we do not use the ACK bit for this
> discussion ).
> > If a PE no longer receives a status message refresh, after 3.5 the
> timer
> > expiration value specified in the last packet the status of that PE
> is
> > deemed to be 0x00000000. The problem that was raised is the fact that
> > that PW might be in "standby mode" with the Preferential forwarding
> bit
> > set. If we arbitrarily clear that bit, the PW can under certain
> > circumstances become active, and therefore cause a traffic
> disruption.
> >
> > I can suggest a few solutions to this problem as follows:
> >
> > 1) specify that the timeout timer MUST be longer the the maximum time
> it
> > takes to detect that the LSP transporting the PW is down. ( my
> preferred
> > approach )
> >
> > 2) change the logic, so that if the status timeout timer expires, we
> > keep the same state, but require that every time a PW is provisioned,
> or
> > the LSP of a Pw transition from a down state to an UP state,  that a
> PW
> > status update be sent in a similar way we send the status 0x0000000
> update
> >
> > 3) Do #2 above but only for some bits like the redundancy bits.
> >
> >
> > Thoughts ?
> >
> > Thanks.
> > Luca
> >
> >
> >
> > _______________________________________________
> > pwe3 mailing list
> > pwe3 at ietf.org
> > https://www.ietf.org/mailman/listinfo/pwe3
> >
> 
> _______________________________________________
> pwe3 mailing list
> pwe3 at ietf.org
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