Re: [foxboro] network storm

  • From: "Johnson, Alex P (IPS)" <alex.johnson@xxxxxxxxxxxxxxxx>
  • To: <foxboro@xxxxxxxxxxxxx>
  • Date: Fri, 6 Feb 2009 14:52:29 -0500

The FCP, ZCP, and FCM are designed to hold up under a storm though 
communications to the FCM from a ZCP if both are on the MESH will be impaired.

Since FCPs do not use FCMs, they will not have an issue in the event of such a 
storm. They talk directly to the FBMs over an IEEE 1118 bus.

In general, I prefer to see the FBMs off the MESH. It just seems prudent.

The ZCP supports that mode of operation just as the CP60 did. However, you do 
give up the V8 SOE mechanism and the TDR/TDA support under the ZCP because it 
lacks those services in its image. The FCP does have them.

As a rule of thumb, I recommend FCPs over ZCPs in almost all cases.


Regards,
 
Alex Johnson
Invensys Process Systems
10900 Equity Drive
Houston, TX 77041
713 329 8472 (desk)
713 329 1600 (operator)
713 329 1944 (SSC Fax)
713 329 1700 (Central Fax)
alex.johnson@xxxxxxxxxxxxxxxx

-----Original Message-----
From: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx] On 
Behalf Of Jones
Sent: Friday, February 06, 2009 1:35 PM
To: foxboro@xxxxxxxxxxxxx
Subject: Re: [foxboro] network storm

Is it correct to say there would be no disruption between the CP and FCM if
FCP270's were used instead of ZCP270's for an event similar to this?

Jones

-----Original Message-----
From: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx] On
Behalf Of c.a.wolfschlag@xxxxxxxxxxxxxx
Sent: Friday, February 06, 2009 8:44 AM
To: foxboro@xxxxxxxxxxxxx
Subject: Re: [foxboro] network storm

We had a similar situation several years ago.  We had a planned electrical
outage but we wanted to keep our I/A up so we used a generator to feed the
UPS that provides normal power.  At the time we thought the UPS would filter
the generator noise but later discovered the UPS was not a true "on-line"
UPS.

-----Original Message-----
From: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx] On
Behalf Of Doucet, Terrence
Sent: Friday, February 06, 2009 8:01 AM
To: foxboro@xxxxxxxxxxxxx
Subject: Re: [foxboro] network storm

Mike,

The extension cord if used with a drill or saw or similar tool, could have
been the cause of electrical noise entering your network. The Foxboro
signals themselves are fibre so thus immune, but the switches are high speed
computing devices that are susceptible to electrical noise. High frequency
noise on the neutral could pass right through the power supply section of
the switch and saturate the electronics.

If you want to read about just how weird electrical noise can be, read
through NPS-EC-07-002 (USA Naval Post-Graduate school) in Section 3.1.5
where they discuss how a defective utility pole (wood) caused a problem at a
naval radio station, two miles down the road!

http://www.nps.edu/Research/publications/07techrpt.html

I suspect you can easily justify a ban on the practice of using tools in the
vicinity of your switches at your facility.


Terry Doucet, Eng.


-----Message d'origine-----
De : foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx] De
la part de Michael Jaudon
Envoyé : February 5, 2009 6:46 PM
À : foxboro@xxxxxxxxxxxxx
Objet : Re: [foxboro] network storm

Terry,
Nobody was doing any work on the DCS at all.

The only thing we have found, at this point, is a contractor had an
extension cord plugged into a wall outlet located in the room with the root
switch.  He was using this outlet during the time period we had trouble.
I'm not an electrical guy but I'm told that the "neutral" is common with the
UPS circuit and with the "dirty" regular power (sorry about that Gaylon)
whatever that means.

I know that's a stretch but nothing else at this point is obvious.

Gaylon,  I got your document that was posted on the Cassandra website and it
has been thoroughly discussed.  I may give you a call tomorrow...if not I'll
see you at the SEUG meeting.

All is well at the moment but everyone is uneasy.

Thanks for everyone's input.

Mike Jaudon
Tronox, LLC

On Thu, Feb 5, 2009 at 3:58 PM, Doucet, Terrence <tdoucet@xxxxxxxxxxxxxxxxxx
> wrote:

> Mike,
>
> Cycling power gets you out of trouble relatively quickly but you still do
> not know what caused the trouble. Was there any work going on with any of
> the switches or devices connected to the MESH? Gaylon mentions the Loop
> Detection Policy. If this is not enabled you can easily trigger a storm by
> interposing a HUB between a station on your MESH and then "accidentally"
> connecting a second port on your HUB back to the MESH. But this would kill
> you right away, so unless someone was playing with cables, that is not the
> cause.
>
> Was anyone testing a new program on an AW? If they were performing a whole
> lot of omget's (or the AIMAPI equivalent) without pausing, that might get
> you a storm.
>
> Terry Doucet, Eng.
>
>
>
> -----Message d'origine-----
> De : foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx] De
> la part de Hicks, Gaylon F
> Envoyé : February 5, 2009 4:00 PM
> À : foxboro@xxxxxxxxxxxxx
> Objet : Re: [foxboro] network storm
>
> Hi Mike,
>
> I am Chicken Little no more!  This happens to be one of my favorite pet
> peeves and soapbox issues with the Foxboro mesh network.  Boring
> discussion below.
>
> There are things you can do in the switches to reduce your vulnerability
> to these network storms.  One is to configure all your broadcast packet
> limits on all 100MB ports to 500 packets/second, and if your switches
> will support it, implement the Loop Detection Policy (LDP) algorithm.
> There is also a multicast packet suppression policy you can implement,
> but Foxboro does not officially support that.  And (my personal
> favorite) you can implement VLANs to segment your ZCP field bus from
> your ZCP Control Network.  Also not officially support, but useful.
>
> One thing we have seen with the ZCPs while doing network storm testing
> is that the ZCP/FCM communications start to get sloooooow, and I/O
> updates slow down.  Depending on your process, this can be a problem.
> We'll probably discuss this issue at the SEUG meeting next week.  Are
> you going to make it?  Either way, feel free to give me a call or email
> if you want to talk about this in more detail.
>
> Good luck with everything.
>
> Thanks,
> Gaylon Hicks
> TVA - Browns Ferry
>
>
> -----Original Message-----
> From: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx]
> On Behalf Of Michael Jaudon
> Sent: Thursday, February 05, 2009 1:27 PM
> To: foxboro@xxxxxxxxxxxxx
> Subject: [foxboro] network storm
>
> We experienced a first for our plant site today.  We had all
> workstations,
> on the mesh side of the network, to "smurf" out.  Upon visually checking
> our
> ZCP270s I noticed that of each of the ZCP270s had gone single with it's
> associated FT module gone to red/green.
> Looking at the switches...we have 3 sets of switches including the root
> switch.  On each of the switches the lights were all flashing rapidly
> and in
> unison.  It wasn't until we cycled the power on the root switches (one
> at a
> time) that the network came back.
>
> Talking to our field service rep...he said the situation we had was a
> "network storm".  The cause is unknown.
>
> My question is has anyone ever experienced a "network storm" on a mesh
> network and if so what caused it?
>
> Our mesh network has been in operation since Oct 2008 and this is the
> first
> issue we have had with it.
>
> We are running a Mesh Network version 8.4.1.
>
> --
> Mike Jaudon
> Tronox, LLC
> Hamilton, MS
>
>
>
>

 



 
 
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