Subject: Re: [mpls] [CCAMP] New Draft Notification: draft-dong-ccamp-rsvp-te-plr-designation-00

From: Jie Dong <[email-masked]>
Date: Mon, 15 Mar 2010 11:15:58 +0800

Sorry for any duplication. I just found this mail didn't appear in the
mailing lists.

> > [Jie] This can be a solution for controlling backup LSPs,
> but it may
> > not work in all scenarios. One example is even when there is enough 
> > bandwidth, operators may do not want to reserve such bandwidth for 
> > backup LSPs.
> > 	
> 
> That seems a bit awkward to me. Usually if you provision backup 
> capacity and you can accommodate a primary TE LSP, why would you want 
> not to do it ?
SP can choose to protect some specific nodes based on network topology,
resource, policy, etc. 
Sometimes more protection LSPs do not mean higher availability.
There can be a case like this: 
The SP has the knowledge that some nodes on the path are using some other
mechanisms to insure survivability, thus a local repair for such nodes is
unneeded. Thus explicitly inform this can save resources of establishing and
maintaining unneeded backup LSPs. 
In this case, the key point here is not whether there is enough bandwidth,
but to determine whether backup paths are needed. If such backup LSPs are
unnecessary, there is no need to waste bandwidth on them.

Besides, based on RFC 4090, all the nodes(except the egress) along the LSP
will be candidate PLRs and will spend resources on establishment and
maintenance of backup paths. 
With this draft, non-PLR nodes do not need to participate in fast reroute
processing.

> Then if you cannot accommodate
> them all, there many existing techniques.
Do you mean RFC 4873 ? 

> Last but not least such mechanism requires to know the path 
> in advance to be effective. What do you do when you reroute ?
I don't get your point here. Could you please give more clarification?

Best regards,
Jie

> 
> >
> > Best regards,
> > Jie
> >
> >
> > 	On Mar 3, 2010, at 9:29 AM, Jie Dong wrote:
> >
> >
> >
> > 		Dear all,
> > 		
> > 		There is a new internet draft:
> > draft-dong-ccamp-rsvp-te-plr-designation-00:
> > 	
> > 
> http://tools.ietf.org/html/draft-dong-ccamp-rsvp-te-plr-designation-00
> > 		
> > 		The abstract is as follows:
> > 		
> > 		This document defines RSVP-TE extensions which 
> enable the ingress 
> > node to
> > 		designate particular LSRs along the path as 
> Points of Local Repair 
> > (PLRs) of
> > 		the protected LSP, and further indicate the 
> protection type of each 
> > PLR.
> > 		These mechanisms could enhance the control over 
> the establishment of 
> > backup
> > 		LSPs, and also could save the resources needed 
> for establishing and
> > 		maintaining unnecessary backup LSPs.
> > 		
> > 		Comments are appreciated.
> > 		
> > 		
> > 		
> > 		Best regards,
> > 		Jie
> > 		
> > 		
> > 		_______________________________________________
> > 		CCAMP mailing list
> > 		[email-masked]
> > 		https://www.ietf.org/mailman/listinfo/ccamp
> > 		
> >
> >
> >
>