Subject: [mpls] Reg: Implemention of Label Request

From: Tonuka SinhaRay <[email-masked]>
Date: Mon, 20 Jul 2009 10:59:18 +0530

Hi Guys
I have little confusion on the following sections of RFC 5036.

As per the Section 3.5.7.1.3, I understand that if two LSRs operating in
Downstream on Demand mode, the upstream LSR is responsible for requesting
the Label mapping message. For this scenario, I understand that the upstream
LSR must generate Label request when conditions mentioned in Section 3.5.8.1
matches.
According to section 3.5.8.1 of RFC 5036, I understand that the generation
of Label request packet is not must clause.

Please clarify the following queries:

1) Whether the support for Label request message in an LSR mandatory?

2) If the support for Label request is not mandatory, then what will be
procedure for exchange of labels between two LSRs (not supporting Label
request) operating in Downstream on Demand?

With regards,
Tonuka

---

From: Santanu Ganguly <[email-masked]>
Date: Mon, 20 Jul 2009 10:02:22 +0100

Hi Tonuka,

IMHO, my personal interpretation of RFC 5036 is support for Label Request
Packet *should be mandatory* ( I maybe wrong though).
For example, consider conditions of section 3.5.8.1 and 3.5.7.1.3 of RFC
5036

*3.5.7.1.3*: "In general, the upstream LSR is responsible for requesting
label  mappings when operating in Downstream on Demand mode....an LSR
operating in Downstream on Demand mode SHOULD NOT be  expected to send
unsolicited mapping advertisements.  Therefore, if  the downstream LSR is
operating in Downstream on Demand mode, the upstream LSR is responsible for
requesting label mappings as needed."

*3.5.8.1*.  Label Request Message Procedures

  " The Request message is used by an upstream LSR to explicitly
request that the downstream LSR assign and advertise a label for a FEC."

If the support for Label Request Packets do not exist, then it may become a
challenge to fullfill the above conditions.

This is just my humble observation. It will be interesting to avail of the
opinions of the more learned of our colleagues.

Best Regards

santanu

_________________________________________
*Santanu Ganguly*
*Sr. Consultant, PS*
*Riverbed Technology Inc.*
*UK

*
On Mon, Jul 20, 2009 at 6:29 AM, Tonuka SinhaRay <[email-masked]> wrote:

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