Subject: Re: [Pce] Suggestion in draft-wu-pce-pcep-link-bw-utilization regarding MRUP calculation

From: Dhruv Dhody <[email-masked]>
Date: Sat, 8 Feb 2014 13:38:21 +0530

Hi WG,

Here is the update
to the I.D. 
with the correction made to Link Reserved Bandwidth Utilization
 
(LRBU)
 
calculation and its respective objective function
 
Maximum Reserved Under-Utilized Path
 
(MRUP).

Regards,
Dhruv

A new version of I-D, draft-wu-pce-pcep-link-bw-utilization-02.txt
> has been successfully submitted by Dhruv Dhody and posted to the
> IETF repository.
> Name:           draft-wu-pce-pcep-link-bw-utilization
> Revision:       02
> Title:          Extensions to Path Computation Element Communication
> Protocol (PCEP) for handling Link Bandwidth Utilization
> Document date:  2014-02-07
> Group:          Individual Submission
> Pages:          15
> URL:            http://www.ietf.org/internet-
> drafts/draft-wu-pce-pcep-link-bw-utilization-02.txt
> Status:         https://datatracker.ietf.org/
> doc/draft-wu-pce-pcep-link-bw-utilization/
> Htmlized:       http://tools.ietf.org/html/
> draft-wu-pce-pcep-link-bw-utilization-02
> Diff:           http://www.ietf.org/rfcdiff?
> url2=draft-wu-pce-pcep-link-bw-utilization-02
> Abstract:
>    The Path Computation Element Communication Protocol (PCEP) provides
>    mechanisms for Path Computation Elements (PCEs) to perform path
>    computations in response to Path Computation Clients (PCCs) requests.
>    Link bandwidth utilization considering the total bandwidth of a link
>    in current use for the forwarding is an important factor to consider
>    during path computation.  This document describes extensions to PCEP
>    to consider them as new constraints during path computation.
>
>
>
> Please note that it may take a couple of minutes from the time of
> submission
> until the htmlized version and diff are available at tools.ietf.org.
> The IETF Secretariat

On Fri, Jan 24, 2014 at 6:29 PM, Dhruv Dhody <[email-masked]> wrote:

> Hi PCErs,
>
> Authors have received a following suggestion to change the description for
> the new objective function
> Maximum Reserved Under-Utilized Path (MRUP) [
> http://tools.ietf.org/html/draft-wu-pce-pcep-link-bw-utilization-01#section-6.2
> ].
>
> We agree that the use of Maximum reservable bandwidth R(L) would be the
> correct way. We plan to make this change in the next revision.
>
> Name: Maximum Reserved Under-Utilized Path (MRUP)
>
>
>
> Description: Find a path P such that (Min {(R(Lpi)- ru(Lpi)) /
>
> R(Lpi), i=1...K } ) is maximized.
>
> Regards,
> Dhruv
>
> ---------- Forwarded message ----------
> From: Avantika <[email-masked]>
> Date: Fri, Jan 24, 2014 at 12:11 PM
> Subject: Suggestion in draft-wu-pce-pcep-link-bw-utilization regarding
> MRUP calculation
> To: Dhruv Dhody <[email-masked]>, Qin Wu <[email-masked]>, "
> [email-masked]" <[email-masked]>
> Cc: Udayasree palle <[email-masked]>, "[email-masked]" <
> [email-masked]>
>
>
>  Hi Authors!
>
>
>
> I have a suggestion regarding the formula used for optimization using
> objective function MRUP in draft-wu-pce-pcep-link-bw-utilization.
>
>
>
> As per the draft,
>
>
>
> Name: Maximum Reserved Under-Utilized Path (MRUP)
>
>
>
> Description: Find a path P such that (Min {(c(Lpi)- ru(Lpi)) /
>
> c(Lpi), i=1...K } ) is maximized.
>
>
>
>
>
> Let me take the example of below topology,
>
>
>
>   100(max reservable BW on each link)
>
>
>
> Source                   Destination
>
> A------------------------C
>
> |                        |
>
> |                        |
>
> |                        |
>
> |                        |
>
> B------------------------D
>
>
>
> LSP1 : BW 20
>
> LSP2 : BW 20
>
> LSP3 : BW 40
>
>
>
> Every time a LSP is established path A-C, the RSVP-traffic flowing through
> them, let's say, is approximately 60% of the current reserved.
>
>
>
> After each LSP is established, the output of the formula ((c(Lpi)-
> ru(Lpi)) / c(Lpi))
>
> Consider link A-C
>
> LSP1: (20 - 12)/20
>
> LSP2: (40 - 24)/40
>
> LSP3: (80 - 48)/80
>
>
>
> Always remains as 0.4.
>
>
>
> In my opinion, if instead of using Current Reserved bandwidth, c(L) in the above formula, if we use Maximum reservable bandwidth on link L, denoted R(L).
>
>
>
> Name: Maximum Reserved Under-Utilized Path (MRUP)
>
>
>
> Description: Find a path P such that (Min {(R(Lpi)- ru(Lpi)) /
>
> R(Lpi), i=1...K } ) is maximized.
>
>
>
>
>
> Consider link A-C
>
> LSP1 : (100 - 12)/100 = 0.88
>
> LSP2 : (100 - 24)/100 = 0.76
>
> LSP3 : (100 - 48)/100 = 0.52
>
>
>
> This gives a much clearer reserved utilization for the link.
>
>
>
> Also, now if the OF MRUP is used for the path computation:
>
>
>
> LSP1 : A-C
>
> LSP2 : A-B-D-C
>
> LSP3 : A-C
>
>
>
> Hence we get a more diversified path using MRUP OF.
>
>
>
> Please let me know your opinion regarding the same.
>
>
>
> Regards,
>
> Avantika
>
>
>
>
>
>
>
>