The MPLS WG Archive

[Shahram Davari <Shahram_Davari@pmc-sierra.com>]

Hi Sumit,

>-----Original Message-----
>From: sumit singh [mailto:sumit_s@rediffmail.com]
>Sent: Wednesday, August 27, 2003 5:03 AM
>To: rsvp@isi.edu
>Cc: mpls@UU.NET; flefauch@cisco.com
>Subject: Establishing E / L- LSPs with Bandwidth Reservation 
>
>
>Hello,
>
>I have some questions in the RFC 3270 - MPLS Support of 
>Differentiated Services.
>
>What does establishing an E or L LSP with bandwidth(BW) 
>reservation mean? Does it mean that the BW that has been 
>'reserved', for say an L-LSP should be subtracted from the 
>corresponding PSC's BW pool before performing the admission 
>control for another L LSP with BW reservation request for the same 
>PSC?

Yes, correct.

>
>For example, assume a link with 10 Mbps BW reserved for a certain 
>PSC. Now a request comes for a L LSP with required BW reservation 
>of 5 Mbps and is admitted. Now if another L LSP request comes with 
>the same PSC, and BW requirement of 7 Mbps, should I reject the 
>request or accept it? (considering that I cannot adjust the queue 
>weights dynamically)?

The second L-LSP will be rejected unless its traffic is reduced
a rate that is < 5 Mbps (for example by sending some portion of the traffic over another L-LSP).

>
>Also, what does reserving BW for an E LSP request (with multiple 
>PSCs) mean? Should I then subtract the LSP's required BW from the 
>total BW of the related PSCs, if I accept this LSP request?

Yes.
 
>If yes, then how should one decide from which of the corresponding 
>PSCs' BW one should subtract the BW required for that E LSP?

You can't. But this mode should only be used when you don't need to
differentiate between the BW of different PSCs in the E-LSP. For example when the E-LSP carries AF1x and AF2x.

-Shahram

>
>Please help me understand.
>
>Regards,
>Sumit
>
>
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