Subject: Re: SDL Performance

From: [email-masked]
Date: Tue, 22 Jun 1999 10:35:34 -0400 (EDT)

Dominic,

You'll find the results for the bit-synchronous case in the soon 
to be posted I-D on SDL on Packet-over-lightwave (POL).

Enrique J. Hernandez-Valencia		Phone: (732) 949-6153
Bell Laboratories, 3H-313		FAX:   (732) 834-5906
Holmdel, NJ 07733-3020, USA		Email: [email-masked]

> From [email-masked] Tue Jun 22 08:50:59 1999
> Delivered-To: [email-masked]
> From: Dominic Schupke <[email-masked]>
> X-Accept-Language: en
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> To: [email-masked]
> Subject: SDL Performance
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> 
> Hello,
> 
> In the SDL specification (http://www.lucent.com/micro/tic/docs/sdl.pdf)
> I interpreted the results for service unavailability (and thus Mean Time
> To Frame) in dependence on the number of framers as been calculated for
> the octet-synchronous case, e.g. PPP/SDL/SDH (draft-ietf-pppext-sdl-02).
> Are there any calculations available for the bit-synchronous case?
> 
> Best regards,
> Dominic Schupke
> 
> -- 
> Dominic A. Schupke 
> Institute of Communication Networks, Munich University of Technology
> Building 9, 1st floor, Room 1910, Arcisstr. 21, 80290 Munich, Germany
> Tel.: +49 (0)89/289-2-3511, Fax: +49 (0)89/289-6-3511
>

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From: Dominic Schupke <[email-masked]>
Date: Mon, 28 Jun 1999 18:30:11 +0200

Dear Enrique,

Thank you for the information about SDL in bit-synchronous mode.

According to the performance results of the SDL specification in
octet-synchronous mode, the average overlap (given overlap) of all
framers being out-of-service is much less than 354 bytes for >=2 framers
and for consecutive 354-byte-packets, whereas for 1 framer the average
overlap is 32768 bytes. Did you assume for >=2 framers that the (false)
lengths found by the framers are maximal 354 bytes (i.e. equally
distributed between 0..354 bytes)?

Best regards,
Dominic Schupke

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From: "Enrique J. Hernandez-Valencia" <[email-masked]>
Date: Mon, 28 Jun 1999 14:54:40 -0400

> distributed between 0..354 bytes)?

Yes we did. This is on the conservative side since the average Internet packet
size is typically a bit less than that.

Regards,

Enrique

-- 
======================================================================
Enrique J. Hernandez-Valencia		email:  [email-masked]
Bell Laboratories				[email-masked]
Lucent Technologies			
Room 3H-313				phone:	732-949-6153
Holmdel, NJ 07733, USA			fax:	732-834-5906
=====================================================================

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From: Dominic Schupke <[email-masked]>
Date: Tue, 29 Jun 1999 11:22:55 +0200

> size is typically a bit less than that.
Is this feasible? Assuming that the (false) lengths found by the framers
are equally distributed between 0..l_max bytes (l_max << 65535) means
also that the framers have to be configured to find SDL frames with
lengths <= l_max only. Thus one has to restrict the payload length to
l_max.

Best regards,
Dominic