The MPLS WG Archive

Cell Relay Retreat>MPLS WG Archive>month:2006-Dec> msg00109



[Date Prev][Date Next][Thread Prev][Thread Next]  
  [Date Index][Thread Index][Author Index][Subject Index]

[mpls] LDP newbie question

  • From: "Abhishek Verma" <abhishekv.verma@gmail.com>
  • Date: Wed, 27 Dec 2006 09:46:47 +0530
  • Cc: mpls@lists.ietf.org
  • DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com;h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references;b=d1BIrzUBcPbJ4iiwF1h96Vn1bsvT35DBjvmViBSKyt4F5MRa5TAgoQfyKPoZXpgXASxx4+k+T2gK+ydfCX3MitmZKYgZpUpsSuzDpzhIQeK7xkBV8MtPahvZM6Ra+qp8zg5tDNuY/ISTKfQV6Tx4k5iOkGPRWt1XZEq1GkbO3Is=

Greetings Yu!

The example that you have taken is slightly different.

I don't mind LDP3 forwarding the label advertisement it learnt from
LDP1 to LDP2 or vice-versa. What i dont comprehend is why an LDP
router would advertise the label binding back to the neighbor it
learnt that label from?

Thanks,
Abhishek

On 12/26/06, Yu Yi <yuyi@nortel.com> wrote:
> Hi Abhishek,
>
>    It is because that LDP2 think it is possible that LDP1 will want LDP2 send a lable if the next hop is change to LDP2 on LDP1.   But in your case it is impossible. Because the fec(1.1.1.1) is a loopback IP address on LDP1.  There is no chance for LDP1 to select LDP2 as the nexthop for 1.1.1.1.  In this case LDP1 should release the label which LDP2 send.
>    Please consider another case:
>      |------------------------------|
>   LDP1 -----  LDP2 ----- LDP3
>
>     1.1.1.1 is a loopback IP address on LDP1.  So LDP3 will receive a mapping from LDP2 for fec 1.1.1.1(Suppose the metric of link between LDP1/LDP3 is very large).  LDP3 will send a mapping to LDP2. This label will be used if the link between LDP1/LDP2 is down.
>
> Thanks,
> Yu
>
> -----Original Message-----
> From: Abhishek Verma [mailto:abhishekv.verma@gmail.com]
> Sent: 2006Äê12ÔÂ23ÈÕ 9:23 AM
> To: mpls@lists.ietf.org
> Subject: [mpls] LDP newbie question
>
> Hi,
>
> LDP1 -- LDP2
>
> I have two LDP peers 1 and 2. LDP1 advertises its loopback IP address (say 1.1.1.1) to LDP2 with a label of 3. Is there a reason for LDP2 too also advertise 1.1.1.1 back to LDP1 with some label?
>
> Thanks,
> Abhishek
>
> _______________________________________________
> mpls mailing list
> mpls@lists.ietf.org
> https://www1.ietf.org/mailman/listinfo/mpls
>

_______________________________________________
mpls mailing list
mpls@lists.ietf.org
https://www1.ietf.org/mailman/listinfo/mpls