The MPLS WG Archive

[Nick Weeds <NPW@datcon.co.uk>]

Edward,

The draft you mention has been superceded.  The latest draft is
draft-brittain-mpls-ldp-ft-00.txt.  (This latest draft combines the earlier
farrel and matthews drafts).

	Nick.

> Nick Weeds
> Software Developer
> Network Convergence Group
> Data Connection Ltd
> Tel:	+44 1244 313440		Fax:	+44 1244 312422
> Email:	npw@datcon.co.uk		Web:
http://www.datcon.co.uk
> 


> -----Original Message-----
> From: Edward Brookhouse [mailto:ebroo@setuidzero.org]
> Sent: 24 August 2000 21:35
> To: Eric Gray; 'Yuan Gu'; mpls@UU.NET
> Subject: RE: questions on mpls-ldp-09
> 
> 
> 
> Is the draft-farrel-mpls-ldp-ft-00.txt the latest version of 
> the draft ??
> 
> Thanks 
> 
> Edward
> 
> 
> -----Original Message-----
> From: owner-mpls@UU.NET [mailto:owner-mpls@UU.NET]On Behalf 
> Of Eric Gray
> Sent: Thursday, August 24, 2000 9:49 AM
> To: 'Yuan Gu'; mpls@UU.NET
> Subject: RE: questions on mpls-ldp-09
> 
> 
> Yuan,
> 
> 	Please see embedded comments below.
> 
> > -----Original Message-----
> > From: Yuan Gu [mailto:guy@sh.bel.alcatel.be]
> > Sent: Wednesday, August 23, 2000 8:43 PM
> > To: mpls@UU.NET
> > Subject: questions on mpls-ldp-09
> > 
> > 
> > Dear All:
> > 
> > I have some questions on  mpls-ldp-09.txt:
> > 
> > 1.How many LSPs can be setup in same session?  
> 
> As many as the two LSRs can maintain state for.
> There is no artificially imposed limit.
> 
> > If session fails for some reason, do all LSPs in 
> > this session have to be released?
> 
> Currently, yes.  See the draft on Fault Tolerant 
> LDP - which was accepted as a working group draft
> at the last IETF meeting - for how LSP state may
> be preserved across LDP sessions.
>  
> > 2. In section 3.5.2.1 Hello Message Procedures
> > Configuration Sequence Number:
> > What kind of session parameter can be changed by passive LSR without
> > noticed by active LSR? If receiving LSR detects a change in the
> > configuration in the sending LSR by detecting the change of
> > Configuration Sequence Number, beside clearing the session 
> > setup backoff
> > delay, what else the receiving LSR does? If receiving LSR 
> playing the
> > passive role and detect the change, what does it do?
> 
> The intent of the configuration sequence number is
> to allow the active peer to be able to find out that
> the passive peer has been re-configured.  
> 
> Why do we want to allow this?  
> 
> Because we can assume that a likely reason why two 
> peers are unable to establish a session is that they 
> have been configured with session parameters that are 
> incompatible.  In this event, each repeated attempt
> will fail and - with exponential back-off - each
> new attempt will be delayed by an interval that is
> twice what it was in the immediate prior attempt.
> Obviously, this delay can grow to be quite large.
> The inclusion of a changed configuration sequence 
> number in a Hello message from the passive peer 
> signals the active peer that it might ignore the
> current retry delay and try again immediately.
> 
> Since the passive peer does not control when an
> attempt will be made (it does not initiate LDP
> session establishment), it does not matter if it
> detects a change in the configuration sequence
> number.  If the active peer has been re-configured,
> it can initiate LDP session establishment on its
> own (without sending a configuration sequence
> number to its passive peer or peers).
> 
> > 
> > Thanks alot.
> > Yuan Gu
> > 
> > 
>