Re: [WISPA] Double Ping Replies
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
Re: [WISPA] Double Ping Replies
Are there any other customers on the second hop? Does the same thing happen to them? Marlon(509) 982-2181 Equipment sales(408) 907-6910 (Vonage) Consulting services42846865 (icq) And I run my own wisp!64.146.146.12 (net meeting)www.odessaoffice.com/wirelesswww.odessaoffice.com/marlon/cam - Original Message - From: Scott Reed To: WISPA General List Sent: Monday, June 05, 2006 5:06 PM Subject: Re: [WISPA] Double Ping Replies 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 -- 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/ -- 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 -- 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 --- -- WISPA Wireless List: wireless@wispa.orgSubscribe/Unsubscribe:http://lists.wispa.org/mailman/listinfo/wirelessArchives: http://lists.wispa.org/pipermail/wireless/ -- WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
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/ -- 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 -- WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
Re: [WISPA] Double Ping Replies
I've seen that with the really old 2 meg Teletronics ap's. It was a timing issue on a really long link. And was unique to a firm ware version or two. What would happen was that the radio would send out the ping, not get a reply soon enough and send out a second one. Then it would get both back. I've also heard of multipath causing something like that, only one goes out but two come back. Both of these scenarios can (and did) cause really strange performance issues. laters, Marlon(509) 982-2181 Equipment sales(408) 907-6910 (Vonage) Consulting services42846865 (icq) And I run my own wisp!64.146.146.12 (net meeting)www.odessaoffice.com/wirelesswww.odessaoffice.com/marlon/cam - Original Message - From: Scott Reed To: wireless@wispa.org Sent: Monday, June 05, 2006 2:43 PM Subject: [WISPA] Double Ping Replies 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 -- WISPA Wireless List: wireless@wispa.orgSubscribe/Unsubscribe:http://lists.wispa.org/mailman/listinfo/wirelessArchives: http://lists.wispa.org/pipermail/wireless/ -- WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
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? 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
