The MPLS WG Archive

[Smakam@aol.com]

Hi,

In the Adelaide MPLS meeting, George Swallow suggested that our ID 
draft-makam-mpls-recovery-frmwrk-0.txt should include the following option:
1+1 protection should include an option where resources on the recovery path 
are dedicated and no traffic is carried over it.
The following is the response from the authors:
1+1 protection switching is usually interpreted to have the same traffic 
running on both the working path and the recovery path and the decision to 
switch over after a fault is made by the PML. Therefore George's suggestion 
should be seen as an option for 1:1 protection switching. The case requested 
by George was not included in the draft for the reason - why go to extra 
trouble of requiring non-work conserving schedulers to assure that the 
dedicated bandwidth for the recovery path is not available to other LSPs. 
George may be thinking of broader applications than data networks. We will 
include this option under 1:1 protection.

Authors also propose the following changes to the terminology:
It is useful in a framework document to define all possible individual 
options regardless some of them are used in practice or not.
In addition, it is useful to define terms for combinations of these options 
that are likely to be of significant practical use. To make the framework 
clear, we can indicate which terms are atomic and which are composite. 

-Atomic Terms-
Initiation of Path Setup: pre-established, established-on-demand
Initiation of Resource Allocation: pre-reserved, reserved-on-demand
Availability of pre-reserved resources on Recovery Path: 
resource-available-to-others (or shared-resource), 
resource-not-available-to-others (or dedicated-resource)
Path Mapping: 1-to-1, m-to-n (including m=1 case), n-to-1 a.k.a. Split Path 
which is FFS

-Composite Terms-
Rerouting = established-on-demand + reserved-on-demand
Protection Switching = pre-established + pre-reserved
1+1 = 1-to-1 + protection switching + dedicated-resource (multicast) + PML 
recovery action
1:1 = 1-to-1 + protection switching + shared-resource + PSL recovery action

This leaves some combinations without specific terms (e.g., pre-established + 
reserved-on-demand, protection switching + dedicated + PSL recovery action). 
If necessary these might be named by adding qualifiers to other terms or 
inventing new composite terms, but that may not be necessary if these are not 
very useful combinations.

We are also addressing some aspects such as extension of the recovery 
framework to include MPLS based optical networks.

We solicit comments from the MPLS WG mailing list on the above proposal as 
well as on the items in the draft.

Cheers,

Vas Makam
Srinivas.Makam@tellabs.com
(630) 512-7217
Tellabs
4951 Indiana Ave.
Lisle, IL 60532