From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ej1-x636.google.com (mail-ej1-x636.google.com [IPv6:2a00:1450:4864:20::636]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 5F9A33CB38 for ; Mon, 12 Jul 2021 16:42:57 -0400 (EDT) Received: by mail-ej1-x636.google.com with SMTP id bu12so37220783ejb.0 for ; Mon, 12 Jul 2021 13:42:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=broadcom.com; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=Vn130OsmW4lfRAzF4WiP/sOEw1mI4QdD1FEERLc8Uck=; b=iNxl6s9DyP7b88otuWFG722aXGJRiWDKnQzXGeJZSJuRI2Lv+vRyL/BfFTY8pot9AP Mwm8h7qb2NHXXd0GVLFsM0xMlsfNAsqZP+Ika1kqmFSXBECo6WPzS+p8aiiPAoNrPYt+ 0bFsmtt8VrdX70XryowrA5ewAYUvYpG/g/c64= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=Vn130OsmW4lfRAzF4WiP/sOEw1mI4QdD1FEERLc8Uck=; b=B4KWM4tu+uMkXJhJlBNXGDOaqnSz0BlJ+qY2bN/wB9jFDJO6PQWPbREW678nODgszG VG2NyWWK5rM2ggcW23x+Zz6K4dPtuXxmpo2Du+1p4wbrrFxbWoNF6Ld+plvzxFdqpL+b tCa4Sd0JSMPXpjNX/g2IfUDlYzYCewtQZWgJPwH1y5NNUpovXHlkqsELA0svnmLFNczT 9cMPhSVubQcB12BZXw833/JErlSOe1ITNBluHWoVvYDp67SnfeOzsd9nWJekDWe5rhI4 G64DqupcCWvfsoDMCRXUYg5IjIWSA9g9cNIs9XwiVs8uDpQdgMsB19tge4vrTUt8RVui Logg== X-Gm-Message-State: AOAM533aDbiSXPr+NHlReE0TxnXQ0B/urHEb4VVOry/pkH7ykTp3jl4E bmBR+KvNdk1J3OFMYx1SDkBi9dlEH0zTY3SXrRyp2x3OW2QlVuebegu/vjowQA9Xmg+uNRh8TrV YtfFgYx7ekWhljzLQLZu+NnLuTEhKpTObG1kQk2hq X-Google-Smtp-Source: ABdhPJxl7Pui+2kIEzupcc7lDfEiLDh/bHu3eMGJhhbkh3ysu4rBFnZRZx4mONxDIfIdxtTwR+jPn8/hBS3vs5vF9dw= X-Received: by 2002:a17:906:4dcf:: with SMTP id f15mr1078745ejw.400.1626122576202; Mon, 12 Jul 2021 13:42:56 -0700 (PDT) MIME-Version: 1.0 References: <1625188609.32718319@apps.rackspace.com> <989de0c1-e06c-cda9-ebe6-1f33df8a4c24@candelatech.com> <1625773080.94974089@apps.rackspace.com> <1625859083.09751240@apps.rackspace.com> <1626111630.69692379@apps.rackspace.com> <9c3d61c1-7013-414e-964d-9e83f596e69d@candelatech.com> <1e8bdf58-2a21-f543-a248-be58bcbddbcf@candelatech.com> In-Reply-To: <1e8bdf58-2a21-f543-a248-be58bcbddbcf@candelatech.com> From: Bob McMahon Date: Mon, 12 Jul 2021 13:42:45 -0700 Message-ID: Subject: Re: [Bloat] Little's Law mea culpa, but not invalidating my main point To: Ben Greear Cc: "David P. Reed" , "Livingood, Jason" , Luca Muscariello , Cake List , Make-Wifi-fast , Leonard Kleinrock , "starlink@lists.bufferbloat.net" , "codel@lists.bufferbloat.net" , cerowrt-devel , bloat Content-Type: multipart/signed; protocol="application/pkcs7-signature"; micalg=sha-256; boundary="0000000000008a0cd405c6f32a0a" X-List-Received-Date: Mon, 12 Jul 2021 20:42:57 -0000 --0000000000008a0cd405c6f32a0a Content-Type: multipart/alternative; boundary="00000000000084a4ef05c6f32abd" --00000000000084a4ef05c6f32abd Content-Type: text/plain; charset="UTF-8" We in WiFi find UDP, while useful, also has severe limitations. The impact to the TCP control loop matters a lot for things like aggregation. Visualizations can be useful but also a bit limiting. We use stats techniques such as PCA which is more mathematical and less visual. We find syscall connect() times as a bit more relevant to user experience than ICMP pings which are typically originated and terminated in kernel space. Bob On Mon, Jul 12, 2021 at 1:32 PM Ben Greear wrote: > UDP is better for getting actual packet latency, for sure. TCP is > typical-user-experience-latency though, > so it is also useful. > > I'm interested in the test and visualization side of this. If there were > a way to give engineers > a good real-time look at a complex real-world network, then they have > something to go on while trying > to tune various knobs in their network to improve it. > > I'll let others try to figure out how build and tune the knobs, but the > data acquisition and > visualization is something we might try to accomplish. I have a feeling > I'm not the > first person to think of this, however....probably someone already has > done such > a thing. > > Thanks, > Ben > > On 7/12/21 1:04 PM, Bob McMahon wrote: > > I believe end host's TCP stats are insufficient as seen per the "failed" > congested control mechanisms over the last decades. I think Jaffe pointed > this out in > > 1979 though he was using what's been deemed on this thread as "spherical > cow queueing theory." > > > > "Flow control in store-and-forward computer networks is appropriate for > decentralized execution. A formal description of a class of "decentralized > flow control > > algorithms" is given. The feasibility of maximizing power with such > algorithms is investigated. On the assumption that communication links > behave like M/M/1 > > servers it is shown that no "decentralized flow control algorithm" can > maximize network power. Power has been suggested in the literature as a > network > > performance objective. It is also shown that no objective based only on > the users' throughputs and average delay is decentralizable. Finally, a > restricted class > > of algorithms cannot even approximate power." > > > > https://ieeexplore.ieee.org/document/1095152 > > > > Did Jaffe make a mistake? > > > > Also, it's been observed that latency is non-parametric in it's > distributions and computing gaussians per the central limit theorem for OWD > feedback loops > > aren't effective. How does one design a control loop around things that > are non-parametric? It also begs the question, what are the feed forward > knobs that can > > actually help? > > > > Bob > > > > On Mon, Jul 12, 2021 at 12:07 PM Ben Greear > wrote: > > > > Measuring one or a few links provides a bit of data, but seems like > if someone is trying to understand > > a large and real network, then the OWD between point A and B needs > to just be input into something much > > more grand. Assuming real-time OWD data exists between 100 to 1000 > endpoint pairs, has anyone found a way > > to visualize this in a useful manner? > > > > Also, considering something better than ntp may not really scale to > 1000+ endpoints, maybe round-trip > > time is only viable way to get this type of data. In that case, > maybe clever logic could use things > > like trace-route to get some idea of how long it takes to get 'onto' > the internet proper, and so estimate > > the last-mile latency. My assumption is that the last-mile latency > is where most of the pervasive > > assymetric network latencies would exist (or just ping 8.8.8.8 which > is 20ms from everywhere due to > > $magic). > > > > Endpoints could also triangulate a bit if needed, using some anchor > points in the network > > under test. > > > > Thanks, > > Ben > > > > On 7/12/21 11:21 AM, Bob McMahon wrote: > > > iperf 2 supports OWD and gives full histograms for TCP write to > read, TCP connect times, latency of packets (with UDP), latency of "frames" > with > > > simulated video traffic (TCP and UDP), xfer times of bursts with > low duty cycle traffic, and TCP RTT (sampling based.) It also has support > for sampling (per > > > interval reports) down to 100 usecs if configured with > --enable-fastsampling, otherwise the fastest sampling is 5 ms. We've > released all this as open source. > > > > > > OWD only works if the end realtime clocks are synchronized using > a "machine level" protocol such as IEEE 1588 or PTP. Sadly, *most data > centers don't > > provide > > > sufficient level of clock accuracy and the GPS pulse per second * > to colo and vm customers. > > > > > > https://iperf2.sourceforge.io/iperf-manpage.html > > > > > > Bob > > > > > > On Mon, Jul 12, 2021 at 10:40 AM David P. Reed < > dpreed@deepplum.com dpreed@deepplum.com > > >> wrote: > > > > > > > > > On Monday, July 12, 2021 9:46am, "Livingood, Jason" < > Jason_Livingood@comcast.com > > Jason_Livingood@comcast.com>>> said: > > > > > > > I think latency/delay is becoming seen to be as important > certainly, if not a more direct proxy for end user QoE. This is all still > evolving and I > > have > > > to say is a super interesting & fun thing to work on. :-) > > > > > > If I could manage to sell one idea to the management > hierarchy of communications industry CEOs (operators, vendors, ...) it is > this one: > > > > > > "It's the end-to-end latency, stupid!" > > > > > > And I mean, by end-to-end, latency to complete a task at a > relevant layer of abstraction. > > > > > > At the link level, it's packet send to packet receive > completion. > > > > > > But at the transport level including retransmission buffers, > it's datagram (or message) origination until the acknowledgement arrives > for that > > message being > > > delivered after whatever number of retransmissions, freeing > the retransmission buffer. > > > > > > At the WWW level, it's mouse click to display update > corresponding to completion of the request. > > > > > > What should be noted is that lower level latencies don't > directly predict the magnitude of higher-level latencies. But longer lower > level latencies > > almost > > > always amplfify higher level latencies. Often non-linearly. > > > > > > Throughput is very, very weakly related to these latencies, > in contrast. > > > > > > The amplification process has to do with the presence of > queueing. Queueing is ALWAYS bad for latency, and throughput only helps if > it is in exactly the > > > right place (the so-called input queue of the bottleneck > process, which is often a link, but not always). > > > > > > Can we get that slogan into Harvard Business Review? Can we > get it taught in Managerial Accounting at HBS? (which does address > logistics/supply chain > > queueing). > > > > > > > > > > > > > > > > > > > > > > > > This electronic communication and the information and any files > transmitted with it, or attached to it, are confidential and are intended > solely for the > > use of > > > the individual or entity to whom it is addressed and may contain > information that is confidential, legally privileged, protected by privacy > laws, or > > otherwise > > > restricted from disclosure to anyone else. If you are not the > intended recipient or the person responsible for delivering the e-mail to > the intended > > recipient, > > > you are hereby notified that any use, copying, distributing, > dissemination, forwarding, printing, or copying of this e-mail is strictly > prohibited. If you > > > received this e-mail in error, please return the e-mail to the > sender, delete it from your computer, and destroy any printed copy of it. > > > > > > -- > > Ben Greear >> > > Candela Technologies Inc http://www.candelatech.com > > > > > > This electronic communication and the information and any files > transmitted with it, or attached to it, are confidential and are intended > solely for the use of > > the individual or entity to whom it is addressed and may contain > information that is confidential, legally privileged, protected by privacy > laws, or otherwise > > restricted from disclosure to anyone else. If you are not the intended > recipient or the person responsible for delivering the e-mail to the > intended recipient, > > you are hereby notified that any use, copying, distributing, > dissemination, forwarding, printing, or copying of this e-mail is strictly > prohibited. If you > > received this e-mail in error, please return the e-mail to the sender, > delete it from your computer, and destroy any printed copy of it. > > > -- > Ben Greear > Candela Technologies Inc http://www.candelatech.com > > -- This electronic communication and the information and any files transmitted with it, or attached to it, are confidential and are intended solely for the use of the individual or entity to whom it is addressed and may contain information that is confidential, legally privileged, protected by privacy laws, or otherwise restricted from disclosure to anyone else. If you are not the intended recipient or the person responsible for delivering the e-mail to the intended recipient, you are hereby notified that any use, copying, distributing, dissemination, forwarding, printing, or copying of this e-mail is strictly prohibited. If you received this e-mail in error, please return the e-mail to the sender, delete it from your computer, and destroy any printed copy of it. --00000000000084a4ef05c6f32abd Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
We in WiFi find UDP, while=C2=A0useful, also has severe li= mitations. The impact to the TCP control=C2=A0loop matters a lot for things= like aggregation.=C2=A0

Visualizations can be useful but also a bit= limiting. We use stats techniques such as PCA which is more mathematical a= nd less visual.

We find syscall connect() times as a bit more=C2=A0r= elevant to user experience than ICMP pings which are typically originated a= nd terminated in kernel space.=C2=A0

Bob

On Mon, Jul 12, 2021 at 1:32= PM Ben Greear <greearb@cande= latech.com> wrote:
UDP is better for getting actual packet latency, for sure.=C2=A0= TCP is typical-user-experience-latency though,
so it is also useful.

I'm interested in the test and visualization side of this.=C2=A0 If the= re were a way to give engineers
a good real-time look at a complex real-world network, then they have somet= hing to go on while trying
to tune various knobs in their network to improve it.

I'll let others try to figure out how build and tune the knobs, but the= data acquisition and
visualization is something we might try to accomplish.=C2=A0 I have a feeli= ng I'm not the
first person to think of this, however....probably someone already has done= such
a thing.

Thanks,
Ben

On 7/12/21 1:04 PM, Bob McMahon wrote:
> I believe end host's TCP stats are insufficient as seen per the &q= uot;failed" congested control mechanisms over the last decades. I thin= k Jaffe pointed this out in
> 1979 though he was using what's been deemed on this thread as &quo= t;spherical cow queueing theory."
>
> "Flow control in store-and-forward computer networks is appropria= te for decentralized execution. A formal description of a class of "de= centralized flow control
> algorithms" is given. The feasibility of maximizing power with su= ch algorithms is investigated. On the assumption that communication links b= ehave like M/M/1
> servers it is shown that no "decentralized flow control algorithm= " can maximize network power. Power has been suggested in the literatu= re as a network
> performance objective. It is also shown that no objective based only o= n the users' throughputs and average delay is decentralizable. Finally,= a restricted class
> of algorithms cannot even approximate power."
>
> https://ieeexplore.ieee.org/document/1095152 >
> Did Jaffe make a mistake?
>
> Also, it's been observed that latency=C2=A0is non-parametric in it= 's distributions and computing gaussians=C2=A0per the central limit the= orem for OWD feedback loops
> aren't effective. How does one design a control loop around things= that are non-parametric? It also begs the question, what are the feed forw= ard knobs that can
> actually help?
>
> Bob
>
> On Mon, Jul 12, 2021 at 12:07 PM Ben Greear <greearb@candelatech.com <mail= to:greearb@can= delatech.com>> wrote:
>
>=C2=A0 =C2=A0 =C2=A0Measuring one or a few links provides a bit of data= , but seems like if someone is trying to understand
>=C2=A0 =C2=A0 =C2=A0a large and real network, then the OWD between poin= t A and B needs to just be input into something much
>=C2=A0 =C2=A0 =C2=A0more grand.=C2=A0 Assuming real-time OWD data exist= s between 100 to 1000 endpoint pairs, has anyone found a way
>=C2=A0 =C2=A0 =C2=A0to visualize this in a useful manner?
>
>=C2=A0 =C2=A0 =C2=A0Also, considering something better than ntp may not= really scale to 1000+ endpoints, maybe round-trip
>=C2=A0 =C2=A0 =C2=A0time is only viable way to get this type of data.= =C2=A0 In that case, maybe clever logic could use things
>=C2=A0 =C2=A0 =C2=A0like trace-route to get some idea of how long it ta= kes to get 'onto' the internet proper, and so estimate
>=C2=A0 =C2=A0 =C2=A0the last-mile latency.=C2=A0 My assumption is that = the last-mile latency is where most of the pervasive
>=C2=A0 =C2=A0 =C2=A0assymetric network latencies would exist (or just p= ing 8.8.8.8 which is 20ms from everywhere due to
>=C2=A0 =C2=A0 =C2=A0$magic).
>
>=C2=A0 =C2=A0 =C2=A0Endpoints could also triangulate a bit if needed, u= sing some anchor points in the network
>=C2=A0 =C2=A0 =C2=A0under test.
>
>=C2=A0 =C2=A0 =C2=A0Thanks,
>=C2=A0 =C2=A0 =C2=A0Ben
>
>=C2=A0 =C2=A0 =C2=A0On 7/12/21 11:21 AM, Bob McMahon wrote:
>=C2=A0 =C2=A0 =C2=A0 > iperf 2 supports OWD and gives full histogram= s for TCP write to read, TCP connect times, latency of packets (with UDP), = latency of "frames" with
>=C2=A0 =C2=A0 =C2=A0 > simulated=C2=A0video=C2=A0traffic (TCP and UD= P), xfer times of bursts with low duty cycle traffic, and TCP RTT (sampling= based.) It also has support for sampling (per
>=C2=A0 =C2=A0 =C2=A0 > interval reports) down to 100 usecs if config= ured with --enable-fastsampling, otherwise the fastest sampling is 5 ms. We= 've released all this as open source.
>=C2=A0 =C2=A0 =C2=A0 >
>=C2=A0 =C2=A0 =C2=A0 > OWD only works if the end realtime clocks are= synchronized using a "machine level" protocol such as IEEE 1588 = or PTP. Sadly, *most data centers don't
>=C2=A0 =C2=A0 =C2=A0provide
>=C2=A0 =C2=A0 =C2=A0 > sufficient level of clock accuracy and the GP= S pulse per second * to colo and vm customers.
>=C2=A0 =C2=A0 =C2=A0 >
>=C2=A0 =C2=A0 =C2=A0 > https://iperf2.sourcef= orge.io/iperf-manpage.html
>=C2=A0 =C2=A0 =C2=A0 >
>=C2=A0 =C2=A0 =C2=A0 > Bob
>=C2=A0 =C2=A0 =C2=A0 >
>=C2=A0 =C2=A0 =C2=A0 > On Mon, Jul 12, 2021 at 10:40 AM David P. Ree= d <dpreed@deepp= lum.com <mailto:dpreed@deepplum.com> <mailto:dpreed@deepplum.com
>=C2=A0 =C2=A0 =C2=A0<mailto:dpreed@deepplum.com>>> wrote:
>=C2=A0 =C2=A0 =C2=A0 >
>=C2=A0 =C2=A0 =C2=A0 >
>=C2=A0 =C2=A0 =C2=A0 >=C2=A0 =C2=A0 =C2=A0On Monday, July 12, 2021 9= :46am, "Livingood, Jason" <Jason_Livingood@comcast.com <mailto:Jason_Living= ood@comcast.com>
>=C2=A0 =C2=A0 =C2=A0<mailto:Jason_Livingood@comcast.com <mailto:Jason_Livingood@c= omcast.com>>> said:
>=C2=A0 =C2=A0 =C2=A0 >
>=C2=A0 =C2=A0 =C2=A0 >=C2=A0 =C2=A0 =C2=A0 > I think latency/dela= y is becoming seen to be as important certainly, if not a more direct proxy= for end user QoE. This is all still evolving and I
>=C2=A0 =C2=A0 =C2=A0have
>=C2=A0 =C2=A0 =C2=A0 >=C2=A0 =C2=A0 =C2=A0to say is a super interest= ing & fun thing to work on. :-)
>=C2=A0 =C2=A0 =C2=A0 >
>=C2=A0 =C2=A0 =C2=A0 >=C2=A0 =C2=A0 =C2=A0If I could manage to sell = one idea to the management hierarchy of communications industry CEOs (opera= tors, vendors, ...) it is this one:
>=C2=A0 =C2=A0 =C2=A0 >
>=C2=A0 =C2=A0 =C2=A0 >=C2=A0 =C2=A0 =C2=A0"It's the end-to-= end latency, stupid!"
>=C2=A0 =C2=A0 =C2=A0 >
>=C2=A0 =C2=A0 =C2=A0 >=C2=A0 =C2=A0 =C2=A0And I mean, by end-to-end,= latency to complete a task at a relevant layer of abstraction.
>=C2=A0 =C2=A0 =C2=A0 >
>=C2=A0 =C2=A0 =C2=A0 >=C2=A0 =C2=A0 =C2=A0At the link level, it'= s packet send to packet receive completion.
>=C2=A0 =C2=A0 =C2=A0 >
>=C2=A0 =C2=A0 =C2=A0 >=C2=A0 =C2=A0 =C2=A0But at the transport level= including retransmission buffers, it's datagram (or message) originati= on until the acknowledgement arrives for that
>=C2=A0 =C2=A0 =C2=A0message being
>=C2=A0 =C2=A0 =C2=A0 >=C2=A0 =C2=A0 =C2=A0delivered after whatever n= umber of retransmissions, freeing the retransmission buffer.
>=C2=A0 =C2=A0 =C2=A0 >
>=C2=A0 =C2=A0 =C2=A0 >=C2=A0 =C2=A0 =C2=A0At the WWW level, it's= mouse click to display update corresponding to completion of the request.<= br> >=C2=A0 =C2=A0 =C2=A0 >
>=C2=A0 =C2=A0 =C2=A0 >=C2=A0 =C2=A0 =C2=A0What should be noted is th= at lower level latencies don't directly predict the magnitude of higher= -level latencies. But longer lower level latencies
>=C2=A0 =C2=A0 =C2=A0almost
>=C2=A0 =C2=A0 =C2=A0 >=C2=A0 =C2=A0 =C2=A0always amplfify higher lev= el latencies. Often non-linearly.
>=C2=A0 =C2=A0 =C2=A0 >
>=C2=A0 =C2=A0 =C2=A0 >=C2=A0 =C2=A0 =C2=A0Throughput is very, very w= eakly related to these latencies, in contrast.
>=C2=A0 =C2=A0 =C2=A0 >
>=C2=A0 =C2=A0 =C2=A0 >=C2=A0 =C2=A0 =C2=A0The amplification process = has to do with the presence of queueing. Queueing is ALWAYS bad for latency= , and throughput only helps if it is in exactly the
>=C2=A0 =C2=A0 =C2=A0 >=C2=A0 =C2=A0 =C2=A0right place (the so-called= input queue of the bottleneck process, which is often a link, but not alwa= ys).
>=C2=A0 =C2=A0 =C2=A0 >
>=C2=A0 =C2=A0 =C2=A0 >=C2=A0 =C2=A0 =C2=A0Can we get that slogan int= o Harvard Business Review? Can we get it taught in Managerial Accounting at= HBS? (which does address logistics/supply chain
>=C2=A0 =C2=A0 =C2=A0queueing).
>=C2=A0 =C2=A0 =C2=A0 >
>=C2=A0 =C2=A0 =C2=A0 >
>=C2=A0 =C2=A0 =C2=A0 >
>=C2=A0 =C2=A0 =C2=A0 >
>=C2=A0 =C2=A0 =C2=A0 >
>=C2=A0 =C2=A0 =C2=A0 >
>=C2=A0 =C2=A0 =C2=A0 >
>=C2=A0 =C2=A0 =C2=A0 > This electronic communication and the informa= tion and any files transmitted with it, or attached to it, are confidential= and are intended solely for the
>=C2=A0 =C2=A0 =C2=A0use of
>=C2=A0 =C2=A0 =C2=A0 > the individual or entity to whom it is addres= sed and may contain information that is confidential, legally privileged, p= rotected by privacy laws, or
>=C2=A0 =C2=A0 =C2=A0otherwise
>=C2=A0 =C2=A0 =C2=A0 > restricted from disclosure to anyone else. If= you are not the intended recipient or the person responsible for deliverin= g the e-mail to the intended
>=C2=A0 =C2=A0 =C2=A0recipient,
>=C2=A0 =C2=A0 =C2=A0 > you are hereby notified that any use, copying= , distributing, dissemination, forwarding, printing, or copying of this e-m= ail is strictly prohibited. If you
>=C2=A0 =C2=A0 =C2=A0 > received this e-mail in error, please return = the e-mail to the sender, delete it from your computer, and destroy any pri= nted copy of it.
>
>
>=C2=A0 =C2=A0 =C2=A0--
>=C2=A0 =C2=A0 =C2=A0Ben Greear <greearb@candelatech.com <mailto:greearb@candelatech.com>>
>=C2=A0 =C2=A0 =C2=A0Candela Technologies Inc http://www.candelatech.co= m
>
>
> This electronic communication and the information and any files transm= itted with it, or attached to it, are confidential and are intended solely = for the use of
> the individual or entity to whom it is addressed and may contain infor= mation that is confidential, legally privileged, protected by privacy laws,= or otherwise
> restricted from disclosure to anyone else. If you are not the intended= recipient or the person responsible for delivering the e-mail to the inten= ded recipient,
> you are hereby notified that any use, copying, distributing, dissemina= tion, forwarding, printing, or copying of this e-mail is strictly prohibite= d. If you
> received this e-mail in error, please return the e-mail to the sender,= delete it from your computer, and destroy any printed copy of it.


--
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc=C2=A0 http://www.candelatech.com


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