Thanks again, Jack.

I am going to be working on the fade margin and will post results when I have them.  Hopefully by next weekend.

Scott Reed
Owner
NewWays
Wireless Networking
Network Design, Installation and Administration
www.nwwnet.net


---------- Original Message -----------
From: Jack Unger <[EMAIL PROTECTED]>
To: WISPA General List <wireless@wispa.org>
Sent: Thu, 08 Jun 2006 14:48:44 -0700
Subject: Re: [WISPA] Double Ping Replies

> Scott,
>
> Thanks for letting me know that this problem is occuring along a chain
> of three wireless hops and not just two hops. Unfortunately, this makes
> trying to diagnose and correct the problem remotely (via email) even
> more complex. Without me being "on site" in real time to test and
> analyze the data with you, I can only give you general suggestions for
> you to follow through on.
>
> 1. The 7.7 dBi downstream fade margin from the DLB1300 to the CM9/RB230
> is too low for this 11.3 mile "long link". Radio Mobile shows a link
> distance of 18.22 km which is 11.3 miles. My fade margin "rule of thumb"
> says this link needs a fade margin of at least 11 dB for reliable
> operation. I suggest that you work on correcting this first, as I
> outlined in my first email.
>
> 2. When testing link quality (as opposed to just testing connectivity)
> always use large (1400 byte) ping packets. Large packets will give you a
>  more accurate indication of how the network will perform when handling
> real-world customer traffic.
>
> 3. In the future, on newly-built networks, test throughput in both
> directions and make network adjustments before adding customers onto the
> network. It's a lot easier to fix network problems before customers are
> complaining rather than after they've been complaining.
>
> Feel free to update me after you increase the "long link" fade margin.
>
> Good luck,
>            jack
>
> Scott Reed wrote:
>
> > Thanks Jack. See inline for responses. Also, 2 others asked questions so:
> > 1) I have not found anything to indicate this is getting treated as a
> > broadcast or network IP.
> > 2) Other customers connected to the AP. And yes, they get double ping
> > replies across the long link.
> >
> > Scott Reed
> > Owner
> > NewWays
> > Wireless Networking
> > Network Design, Installation and Administration
> > www.nwwnet.net <http://www.nwwnet.net/>
> >
> >
> > ---------- Original Message -----------
> > From: Jack Unger <[EMAIL PROTECTED]>
> > To: WISPA General List <wireless@wispa.org>
> > Sent: Mon, 05 Jun 2006 19:43:02 -0700
> > Subject: Re: [WISPA] Double Ping Replies
> >
> >  > Scott,
> >  >
> >  > RADIOMOBILE PLOT - The Radio Mobile plot FROM your midpoint CPE back to
> >  > your DLB1300 AP was very helpful and shows a fade margin of 10.7 dB
> >  > which should be enough to provide reliable performance in the upstream
> >  > direction, assuming that the noise level is low (below the receiver
> >  > threshold) at the near-end DLB1300.
> >
> >  >
> >  > DOWNSTREAM FADE MARGIN - What's the fade margin in the downstream
> >  > direction from the DLB1300 TO the midpoint CPE?
> > Fade margin in reverse direction is 7.7dB.
> > The fade margin will
> >  > only be the same as the upstream fade margin if the DLB1300 transmitter
> >  > power output is as high or higher than the CPE transmitter power output
> >  > AND if the midpoint CM9 receiver sensitivity (threshold) is as good as
> >  > the DLB1300 receiver threshold. Can you do a Radio Mobile plot in the
> >  > downstream direction to verify that the downstream fade margin is at
> >  > least 10 dB?
> >  >
> >  > ADDITIONAL TESTING - Do you still get double pings if you ping from the
> >  > first (near end) AP to the midpoint CM9 radio? Yes.
> > Do you get double pings
> >  > if you ping from the near-end DLB1300 AP to the second (midpoint) AP?
> > Yes
> >  >
> >  > PROBLEM HISTORY - What's the history of the problem? Was the system
> >  > working well for a certain period of time and THEN did it start slowing
> >  > down or is this a newly-installed link that has not yet been proven to
> >  > deliver full throughput and reliable performance in both directions?
> > I am not sure. We put up the customers and all was fine, so I don't know
> > that I have done any pings in the 6 months that they have been up. This
> > week one customer called to say his connection was slow. He had
> > mentioned that before and I had not noticed the ping problem, but I
> > assume they are related. I have a new customer, less than 2 weeks that
> > has determined he is getting packet loss, probably on the long link.
> > Just heard that, so have not done any other investigation on his, though
> > it does double reply sometimes.
> >  > If the system worked well for a while and then deteriorated, I'd look
> > for:
> >  >
> >  > a) A hardware problem, or
> >  >
> >  > b) An antenna alignment problem, or
> >  >
> >  > c) A high-noise level problem (the noise increased recently), or
> >  >
> >  > d) Water intrusion, or
> >  >
> >  > e) Some combination of a, b, c, or d.
> >  >
> >  > On the other hand, if the system is newly-installed and is not working
> >  > (and has never worked) the way you expected it to, the problem can still
> >  > be caused by a, b, c, d, or e (above) but it can also be something at
> >  > the wired Ethernet level or at the software configuration level.
> >  >
> >  > FINAL QUESTIONS
> >  >
> >  > 1. Are you absolutely sure that the customer's antenna is high enough to
> >  > have a wireless LOS path (including an unobstructed Fresnel Zone) back
> >  > to the mid-point AP? Is it possible that the 2-mile link is shooting
> >  > through too many treetops?
> > Yes, especially the new one, I can see the AP antenna from the ground
> > and the antenna is 30 feet up. I do not recall seeing the tower from the
> > orginal problem customer, but there is about 1 mile of open field before
> > the first tree.
> >  >
> >  > 2. What is the "normal" ping time range?
> > New Customer:
> > Ping 1: 18 & 24ms
> > Ping 2: 20 & 19ms
> > Ping 3: 19ms
> > Ping 4: 12 & 21ms
> > First customer:
> > Well I just pinged it with no duplicates, but 45, 60, 60, and 190ms.
> > Ping 1: 56 & 66ms
> > Ping 2: 62 & 68ms
> > Ping 3: 85ms
> > Ping 4: 147 & 159ms
> > Ping 1: 249ms
> > Ping 2: 13ms
> > Ping 3: 12ms
> > Ping 4: 10ms
> > So not very consistant and slow, sometimes.
> > POP to AP is very similar to the customer, so I really think the link
> > between the POPs is the issue.
> >
> > I have in hand new 5.8GHz antennae and an RM532 with CM9 card to put at
> > the NOC, rather than the intermediate POP. I am hopeful that moving to
> > 5.8GHz PTP instead of 2.4GHz PtMP. RM Link info for the proposed PTP is
> > attached.
> >
> >
> >  >
> >  > 3. How large are your ping packets?
> > This all with 28 byte packets. 1000 seems pretty similar.
> >  >
> >  > 4. What hardware is located between the midpoint CPE and the midpoint
> >  > AP?
> > Total link NOC to Customer is:
> > RB230 -- TrangoLink10 == TrangoLink 10 -- RB230 -- DLB1300 == CM9 in
> > RB230 -- CM9 in RB230 == SmartBridge Outdoor
> > where -- is wire or on the card and == is wireless.
> >  >
> >  > NEXT STEP - I think that the ping test results that you obtain when you
> >  > ping from the near-end AP to the midpoint CPE and then from the near-end
> >  > AP to the midpoint AP should be helpful in further isolating the
> > problem.
> >  >
> >  > jack
> >  >
> >  > Scott Reed wrote:
> >  >
> >  > > This is an 802.11b hop link. It goes 9.4 miles from a DLB1300 AP with
> >  > > 120* 14dBi sector to a 24dBi Grid on an CM9 in a RB230. >From there
> > it is
> >  > > 2.0 miles to the customer. The AP has a 90* 9dBi (I think) on a CM9.
> >  > > Customer is a 15dBi grid to an SB Outdoor radio.
> >  > >
> >  > > Does the 9.4 mile link constitute a "long link?" It appears the double
> >  > > ping replies are only if I ping from the first AP through the other to
> >  > > the client. Pinging from the clients near AP doesn't get the double
> >  > > replies.
> >  > >
> >  > > RadioMobile plot of link attached.
> >  > >
> >  > > Scott Reed
> >  > > Owner
> >  > > NewWays
> >  > > Wireless Networking
> >  > > Network Design, Installation and Administration
> >  > > www.nwwnet.net <http://www.nwwnet.net/> <http://www.nwwnet.net/>
> >  > >
> >  > >
> >  > > ---------- Original Message -----------
> >  > > From: Jack Unger <[EMAIL PROTECTED]>
> >  > > To: WISPA General List <wireless@wispa.org>
> >  > > Sent: Mon, 05 Jun 2006 15:31:06 -0700
> >  > > Subject: Re: [WISPA] Double Ping Replies
> >  > >
> >  > > > Scott,
> >  > > >
> >  > > > Excessive pings is often a symptom of a poor wireless link. I would
> >  > > > check to be sure that:
> >  > > >
> >  > > > a) The customer's antenna is high enough to provide a good signal
> > back
> >  > > > to the access point
> >  > > >
> >  > > > b) The link is not overly long
> >  > > >
> >  > > > c) There is no hardware problem in their antenna system or radio.
> >  > > >
> >  > > > jack
> >  > > >
> >  > > > Scott Reed wrote:
> >  > > > > I had a customer call to say there connection had not been working
> >  > > well
> >  > > > > today. I started to see what is going on by ping the radio. I
> > get 2
> >  > > > > replies for almost every ping. Average was about 1 at 45ms and
> > one at
> >  > > > > 56ms. The times are longer than normal, but my question is, how
> > do I
> >  > > > > get 2 reponses to a ping? No duplicate addresses, I checked.
> >  > > > > The other way I know there were 2 pings is one of the MTs that is
> >  > > > > between me and the customer showed 2 times the download as upload
> >  > > speed
> >  > > > > in torch, and I was the only one talking to that radio.
> >  > > > > Suggestions on what I need to look for?
> >  > > > >
> >  > > > > Scott Reed
> >  > > > > Owner
> >  > > > > NewWays
> >  > > > > Wireless Networking
> >  > > > > Network Design, Installation and Administration
> >  > > > > www.nwwnet.net <http://www.nwwnet.net/>
> > <http://www.nwwnet.net/> <http://www.nwwnet.net/>
> >  > > > >
> >  > > >
> >  > > > --
> >  > > > Jack Unger ([EMAIL PROTECTED]) - President, Ask-Wi.Com, Inc.
> >  > > > Serving the License-Free Wireless Industry Since 1993
> >  > > > Author of the WISP Handbook - "Deploying License-Free Wireless WANs"
> >  > > > True Vendor-Neutral WISP Consulting-Training-Troubleshooting
> >  > > > Our next WISP Workshop is June 21-22 in Atlanta, GA.
> >  > > > Phone (VoIP Over Broadband Wireless) 818-227-4220 www.ask-wi.com
> > <http://www.ask-wi.com/>
> >  > > <http://www.ask-wi.com/>
> >  > > >
> >  > > > --
> >  > > > WISPA Wireless List: wireless@wispa.org
> >  > > >
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> >  > > >
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> >  > > ------- End of Original Message -------
> >  > >
> >  > >
> > ------------------------------------------------------------------------
> >  > >
> >  >
> >  > --
> >  > Jack Unger ([EMAIL PROTECTED]) - President, Ask-Wi.Com, Inc.
> >  > Serving the License-Free Wireless Industry Since 1993
> >  > Author of the WISP Handbook - "Deploying License-Free Wireless WANs"
> >  > True Vendor-Neutral WISP Consulting-Training-Troubleshooting
> >  > Our next WISP Workshop is June 21-22 in Atlanta, GA.
> >  > Phone (VoIP Over Broadband Wireless) 818-227-4220 www.ask-wi.com
> > <http://www.ask-wi.com/>
> >  >
> >  > --
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> > ------- End of Original Message -------
> >
> > ------------------------------------------------------------------------
> >
> >
> > ------------------------------------------------------------------------
> >
>
> --
> Jack Unger ([EMAIL PROTECTED]) - President, Ask-Wi.Com, Inc.
> Serving the License-Free Wireless Industry Since 1993
> Author of the WISP Handbook - "Deploying License-Free Wireless WANs"
> True Vendor-Neutral WISP Consulting-Training-Troubleshooting
> Next WISP Workshop June 21-22 in Atlanta.
> http://www.ask-wi.com/2002locations.html
> Phone (VoIP Over Broadband Wireless) 818-227-4220  www.ask-wi.com
>
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