Subject: Sending mapping for REC-NEW-FEC

From: "Sreemoolanathan B Iyer" <[email-masked]>
Date: Thu, 27 Jan 2000 09:33:10 +0530

In the Recognise New FEC in the Label Distribution Procedures in  
ldp-06.txt (Appendix A.1.6), according to FEC.1, for downstream 
unsolicited independent control, for each peer we are supposed to 
send a label mapping. No distinction is made for the next hop. Are 
we supposed to send it to the next hop also ?

We can imagine a case where sending a label mapping to the next 
hop can be useful. If the current next hop is using conservative 
mode, he will release the label, on receiving the mappnig. On the 
other hand, if he is using request_never & liberal modes and if at a 
later point of time the network topology changes drastically so that 
we become his next hop for the FEC, the current next hop would 
never be sending us a label_request at that time. If such a situation 
is possible, sending label mapping to the current next hop could be 
useful.

Is this assumption correct ?

Sree.

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From: Bob Thomas <[email-masked]>
Date: Thu, 27 Jan 2000 06:31:53 -0500

Sree,

> we supposed to send it to the next hop also ?

Yes.

Bob

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From: Bob Thomas <[email-masked]>
Date: Thu, 27 Jan 2000 07:12:12 -0500

Sree,

> > Is this assumption correct ?

When LSRs use DU with liberal label retention an LSR can react
to a change in next hop for a destination without interaction
with other LSRs, assuming the new next hop had previously
advertised the label for the destination.

When LSRs use DoD with conservative label retention an LSR
must interact with the new next hop to request a label
for the destination and the old next hop (assuming it
still has a session with it) to release the old label.

Bob

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From: Bob Thomas <[email-masked]>
Date: Thu, 27 Jan 2000 07:12:12 -0500

Sree,

Bob