The MPLS WG Archive

["Gray, Eric" <egray@celoxnetworks.com>]

Kim,

 

            See below...

 

Eric W. Gray

Systems Architect

Celox Networks, Inc.

egray@celoxnetworks.com

508 305 7214

 

...

-----------------------------------------------------------------------------------------

(1) As I know, "Label Request " is only applicable for DoD. But in this line,       

     it is mentioned as the message is also applicable for Downstream Unsolicited Independent Control. 

     Is it right?

Label Request is required for DoD and allowed for DU.  Any implementation 

must support handling of Label Requests for both modes.

(2) What is "Propagating"?

      Could you tell me the reason why the algorithm check the state, 

     "Has LSR previously received and retained a label  mapping for FEC from Next Hop?.", 

      and set "Propgating" with "IsPropagating" or "NotPropagating"? What does it mean?

Propagating state might be thought of as indicating - for independent control

- whether the Label (about to be given) is bound to a downstream Label.

(3) As the summary of A.1.1. Recevie Label Request in RFC 3036, the general procedure of Label Request is as follow:

      - Transmission of a notification ...........

      - Transmission of label mapping .........

      - Transmission of label request ..........

      - Installation of labels ................

      But, in this procedure, the algorithm checks whether the LSR is egress or the LSR has the labels from the Next Hop.

      As far as I think, it looks like that this procedure must be checked before Send_Label procedure or Prepare_Label_Mapping_Attributes.

      Why this procedure is performed after Send_Label procedure?

      Is is right?

I need your help.!!

It is not likely that you could summarize the steps without over simplifying.

There are many modes to consider and - if it could have been summarized 

as easily as this - it would have been.  J

If you consider each combination of modes - one at a time - the procedure

you arrive at for each should make sense.  Even then, you need to cover all

of the possible cases (or states) that might exist at the time of receipt of a

Label Request. You might also look into RFC 3215. These are things you

need to do for yourself.  If you then come up with more specific questions,

you are much more likely to get help.  As it is, you are asking for a simple

explanation of a complex set of instructions that have already been stated 

as simply as possible.

Thanks.