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? 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? Do you get double pings if you ping from the near-end DLB1300 AP to the second (midpoint) AP?

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?
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?

2. What is the "normal" ping time range?

3. How large are your ping packets?

4. What hardware is located between the midpoint CPE and the midpoint AP?


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/>


---------- 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/>
 > >
 >
 > --
 > 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/>
 >
 > --
 > WISPA Wireless List: wireless@wispa.org
 >
 > Subscribe/Unsubscribe:
 > http://lists.wispa.org/mailman/listinfo/wireless
 >
 > Archives: http://lists.wispa.org/pipermail/wireless/
------- 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




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