(usr-tc) USR vs Ascend (3com vs Lucent?)
One of my client ISP's has both USR hiperdsp's and Ascend MAX's. I've noticed that the Max's seem to perform better (ratio of successful connects, number of dropped connections) than the USR's, even when connecting to USR modems. About 2am this morning I had a flash of insight and drove into my office (I have a well-equipped home lab, but needed access to a 4-wire interface. Not much traffic at 2am, and no trouble finding a parking space downtown.) It was worth the trip, I think I hit pay dirt. What I tested was the level the server (ISP) modem was transmitting at. I was surprised to see that is was at -10dbm, which is quite hot. Beacuse of the way digital lines are coded, higher power levels have worse s/n ratios, there aren't at many quantitization bits available at higher powers. I plugged in my laptop, fired up tcm, and looked at the hiperdsp config. It was set for -11dbm. Hmmm. I set it for -15, and yup, I get -14 when I measure it. An off by one error someplace, no doubt. But it gets better. I call into our Max's and measured the level they were sending. Only -14dbm, much lower power, more what I was expecting. Telnet in and check to see what they are set to, -13dbm, another off by one, but this time in the opposite direction! Here's a summary: Configured for Actually sends USR HiperDSP -11dbm -10dbm Ascend Max -13dbm -14dbm I don't have any scripts in place that monitor failure ratios, but if someone does I'd be interested if they could set half their modems to -15dbm (for an output of -14dbm) and see what effect that has. -- Aaron Nabil - To unsubscribe to usr-tc, send an email to "majordomo@xmission.com" with "unsubscribe usr-tc" in the body of the message. For information on digests or retrieving files and old messages send "help" to the same address. Do not use quotes in your message.
Aaron Nabil writes...
Here's a summary: Configured for Actually sends USR HiperDSP -11dbm -10dbm Ascend Max -13dbm -14dbm
One more entry for the above table: USR HiperDSP -15dbm -14dbm And some even more interesting results! The above tests were made with 14.4k connections, I figured that would be an old enough protocol not to have any power negotiation sequences. I retested with 33.6k, and here's what I got. Note that I'm listing the _median_ power, occasionally it would pick a notch higher or lower. 33.6k connections: Configured for Median power USR HiperDSP -11dbm -12dbm USR HiperDSP -15dbm -16dbm Ascend Max -13dbm -16dbm This seems like even more evidence that setting the USR to -15dbm might be worth a try. I'll be looking at 56k next, but the results aren't as meaningful, there isn't a direct correllation between power and s/n in v.90. -- Aaron Nabil - To unsubscribe to usr-tc, send an email to "majordomo@xmission.com" with "unsubscribe usr-tc" in the body of the message. For information on digests or retrieving files and old messages send "help" to the same address. Do not use quotes in your message.
Aaron Nabil writes...
. . . Configured for Median power USR HiperDSP -11dbm -12dbm USR HiperDSP -15dbm -16dbm Ascend Max -13dbm -16dbm
I'll be looking at 56k next, but the results aren't as meaningful, there isn't a direct correllation between power and s/n in v.90.
I tested V.90, it always gets about -16.5dbm independant of the settings or box, which is both expected and reasonable. -- Aaron Nabil - To unsubscribe to usr-tc, send an email to "majordomo@xmission.com" with "unsubscribe usr-tc" in the body of the message. For information on digests or retrieving files and old messages send "help" to the same address. Do not use quotes in your message.
Considering the number of requests I've gotten in the last two hours, I think the'll be plenty of guinia pigs, er, helpful 3com owners testing the -15dbm setting for me. Here's the instructions (at least this works on my TCS 3.6)
Where in TCM do you change these levels. I will change them on a couple of DSPs and see what happens.
Select the modems. Configure/Programmed settings. Select the modems you want to change. Under Line Interface Options, change Transmit Level.
-- Aaron Nabil - To unsubscribe to usr-tc, send an email to "majordomo@xmission.com" with "unsubscribe usr-tc" in the body of the message. For information on digests or retrieving files and old messages send "help" to the same address. Do not use quotes in your message.
Where in the TCM do you set the dbm levels? I looked everwhere on the DSP config settings. Aaron Nabil wrote:
One of my client ISP's has both USR hiperdsp's and Ascend MAX's. I've noticed that the Max's seem to perform better (ratio of successful connects, number of dropped connections) than the USR's, even when connecting to USR modems.
About 2am this morning I had a flash of insight and drove into my office (I have a well-equipped home lab, but needed access to a 4-wire interface. Not much traffic at 2am, and no trouble finding a parking space downtown.) It was worth the trip, I think I hit pay dirt.
What I tested was the level the server (ISP) modem was transmitting at. I was surprised to see that is was at -10dbm, which is quite hot. Beacuse of the way digital lines are coded, higher power levels have worse s/n ratios, there aren't at many quantitization bits available at higher powers.
I plugged in my laptop, fired up tcm, and looked at the hiperdsp config. It was set for -11dbm. Hmmm. I set it for -15, and yup, I get -14 when I measure it. An off by one error someplace, no doubt. But it gets better.
I call into our Max's and measured the level they were sending. Only -14dbm, much lower power, more what I was expecting. Telnet in and check to see what they are set to, -13dbm, another off by one, but this time in the opposite direction!
Here's a summary: Configured for Actually sends USR HiperDSP -11dbm -10dbm Ascend Max -13dbm -14dbm
I don't have any scripts in place that monitor failure ratios, but if someone does I'd be interested if they could set half their modems to -15dbm (for an output of -14dbm) and see what effect that has.
-- Aaron Nabil
- To unsubscribe to usr-tc, send an email to "majordomo@xmission.com" with "unsubscribe usr-tc" in the body of the message. For information on digests or retrieving files and old messages send "help" to the same address. Do not use quotes in your message.
-- Richard Lorbieski - richard@alpha1.net Chief Technical Officer - Senior System Administrator Alpha1 Internet http://www.alpha1.net 409.731.8236 - 877.4.alpha1 (877.425.7421) - To unsubscribe to usr-tc, send an email to "majordomo@xmission.com" with "unsubscribe usr-tc" in the body of the message. For information on digests or retrieving files and old messages send "help" to the same address. Do not use quotes in your message.
On Thu, 7 Oct 1999, Richard Lorbieski wrote:
Where in the TCM do you set the dbm levels? I looked everwhere on the DSP config settings.
Same place as on the quads - at the modem level. Click on the modem status lights, configure, programmed settings, and poke around. Most people don't even know you can change settings for the modems on a DSP card... Kevin
Aaron Nabil wrote:
One of my client ISP's has both USR hiperdsp's and Ascend MAX's. I've noticed that the Max's seem to perform better (ratio of successful connects, number of dropped connections) than the USR's, even when connecting to USR modems.
About 2am this morning I had a flash of insight and drove into my office (I have a well-equipped home lab, but needed access to a 4-wire interface. Not much traffic at 2am, and no trouble finding a parking space downtown.) It was worth the trip, I think I hit pay dirt.
What I tested was the level the server (ISP) modem was transmitting at. I was surprised to see that is was at -10dbm, which is quite hot. Beacuse of the way digital lines are coded, higher power levels have worse s/n ratios, there aren't at many quantitization bits available at higher powers.
I plugged in my laptop, fired up tcm, and looked at the hiperdsp config. It was set for -11dbm. Hmmm. I set it for -15, and yup, I get -14 when I measure it. An off by one error someplace, no doubt. But it gets better.
I call into our Max's and measured the level they were sending. Only -14dbm, much lower power, more what I was expecting. Telnet in and check to see what they are set to, -13dbm, another off by one, but this time in the opposite direction!
Here's a summary: Configured for Actually sends USR HiperDSP -11dbm -10dbm Ascend Max -13dbm -14dbm
I don't have any scripts in place that monitor failure ratios, but if someone does I'd be interested if they could set half their modems to -15dbm (for an output of -14dbm) and see what effect that has.
-- Aaron Nabil
- To unsubscribe to usr-tc, send an email to "majordomo@xmission.com" with "unsubscribe usr-tc" in the body of the message. For information on digests or retrieving files and old messages send "help" to the same address. Do not use quotes in your message.
--
Richard Lorbieski - richard@alpha1.net Chief Technical Officer - Senior System Administrator Alpha1 Internet http://www.alpha1.net 409.731.8236 - 877.4.alpha1 (877.425.7421)
- To unsubscribe to usr-tc, send an email to "majordomo@xmission.com" with "unsubscribe usr-tc" in the body of the message. For information on digests or retrieving files and old messages send "help" to the same address. Do not use quotes in your message.
E-Mail: s1kevin@tims.net Web: http://users.sota-oh.com/~s1kevin/ Unsolicited advertisements processing fee: $50 subject to change without notice - To unsubscribe to usr-tc, send an email to "majordomo@xmission.com" with "unsubscribe usr-tc" in the body of the message. For information on digests or retrieving files and old messages send "help" to the same address. Do not use quotes in your message.
There was some discussion on transmit levels a while back -- check the archives. If I remember right, David Bolen said that ANS made a habit of setting all their modem pools (for AOL mostly) to -13dBm. We had a few people have problems when we tried backing ours down, so for now I've left it alone until I can get a better idea. Complicating things more is that we have both Quads and DSP's, and the Quads default to -11, but the DSP's default (or at least used to default) to -12. The Courier I-Modem I have at home defaults to -12. What the actual transmit power works out to in all these cases at each modulation is anyone's guess... Mike Andrews (MA12) * mandrews@dcr.net * http://www.bit0.com/ VP, sysadmin, & network guy, Digital Crescent Inc, Frankfort KY Internet services for Frankfort, Lawrenceburg, Owenton, & Shelbyville "With sufficient thrust, pigs fly just fine." -- RFC 1925 - To unsubscribe to usr-tc, send an email to "majordomo@xmission.com" with "unsubscribe usr-tc" in the body of the message. For information on digests or retrieving files and old messages send "help" to the same address. Do not use quotes in your message.
On Thu, 7 Oct 1999, Mike Andrews wrote:
There was some discussion on transmit levels a while back -- check the archives. If I remember right, David Bolen said that ANS made a habit of setting all their modem pools (for AOL mostly) to -13dBm.
nod, I have those emails. The thing is, that was on the Quads. The quads could do analog or digital. The default modem templates were optimized for analog calls not digital. So you would have to make some changes to the Quads to optimize for CT1/PRI. David did clarify however that the HDM's didn't have this problem. But that was when they first came out, who knows whats what since then.
We had a few people have problems when we tried backing ours down, so for now I've left it alone until I can get a better idea.
Complicating things more is that we have both Quads and DSP's, and the Quads default to -11, but the DSP's default (or at least used to default) to -12. The Courier I-Modem I have at home defaults to -12. What the actual transmit power works out to in all these cases at each modulation is anyone's guess...
Mike Andrews (MA12) * mandrews@dcr.net * http://www.bit0.com/ VP, sysadmin, & network guy, Digital Crescent Inc, Frankfort KY Internet services for Frankfort, Lawrenceburg, Owenton, & Shelbyville "With sufficient thrust, pigs fly just fine." -- RFC 1925
- To unsubscribe to usr-tc, send an email to "majordomo@xmission.com" with "unsubscribe usr-tc" in the body of the message. For information on digests or retrieving files and old messages send "help" to the same address. Do not use quotes in your message.
----------------------------------------------------- Brian Feeny (BF304) signal@shreve.net 318-222-2638 x 109 http://www.shreve.net/~signal Network Administrator ShreveNet Inc. (ASN 11881) - To unsubscribe to usr-tc, send an email to "majordomo@xmission.com" with "unsubscribe usr-tc" in the body of the message. For information on digests or retrieving files and old messages send "help" to the same address. Do not use quotes in your message.
On Thu, 7 Oct 1999, Brian wrote:
On Thu, 7 Oct 1999, Mike Andrews wrote:
There was some discussion on transmit levels a while back -- check the archives. If I remember right, David Bolen said that ANS made a habit of setting all their modem pools (for AOL mostly) to -13dBm.
nod, I have those emails. The thing is, that was on the Quads. The quads could do analog or digital. The default modem templates were optimized for analog calls not digital. So you would have to make some changes to the Quads to optimize for CT1/PRI.
David did clarify however that the HDM's didn't have this problem. But that was when they first came out, who knows whats what since then.
FWIW... I just blew a 2.0.81 DSP back to factory defaults and it comes up set to -11 now, instead of -12 like it used to. So it looks like both Quads and DSPs default to -11 now. (Courier I-Modem still does -12 on my BRI at home... that would be interesting to experiment on...) Anyway. Given that the measured level and the programmed level tend to vary on both 3Com and Ass^Hcend stuff... anyone have a new consensus as to what we should be using instead of 11? 13? 15? Mike Andrews (MA12) * mandrews@dcr.net * http://www.bit0.com/ VP, sysadmin, & network guy, Digital Crescent Inc, Frankfort KY Internet services for Frankfort, Lawrenceburg, Owenton, & Shelbyville "With sufficient thrust, pigs fly just fine." -- RFC 1925 - To unsubscribe to usr-tc, send an email to "majordomo@xmission.com" with "unsubscribe usr-tc" in the body of the message. For information on digests or retrieving files and old messages send "help" to the same address. Do not use quotes in your message.
Do you have a conclusion on this yet? Does changing these settings have any impact? At 04:46 AM 10/7/99 -0700, you wrote:
I call into our Max's and measured the level they were sending. Only -14dbm, much lower power, more what I was expecting. Telnet in and check to see what they are set to, -13dbm, another off by one, but this time in the opposite direction!
Here's a summary: Configured for Actually sends USR HiperDSP -11dbm -10dbm Ascend Max -13dbm -14dbm
I don't have any scripts in place that monitor failure ratios, but if someone does I'd be interested if they could set half their modems to -15dbm (for an output of -14dbm) and see what effect that has.
-- Aaron Nabil
Thanks, Greg Coffey <gcoffey@vcn.com> Visionary Communications V 307-234-5443 F 307-234-5446 100 N. Center, Casper, WY 82601 www.vcn.com - To unsubscribe to usr-tc, send an email to "majordomo@xmission.com" with "unsubscribe usr-tc" in the body of the message. For information on digests or retrieving files and old messages send "help" to the same address. Do not use quotes in your message.
Greg Coffey writes...
Do you have a conclusion on this yet? Does changing these settings have any impact?
I haven't tried it yet, haven't been around the office much. -a
At 04:46 AM 10/7/99 -0700, you wrote:
I call into our Max's and measured the level they were sending. Only -14dbm, much lower power, more what I was expecting. Telnet in and check to see what they are set to, -13dbm, another off by one, but this time in the opposite direction!
Here's a summary: Configured for Actually sends USR HiperDSP -11dbm -10dbm Ascend Max -13dbm -14dbm
I don't have any scripts in place that monitor failure ratios, but if someone does I'd be interested if they could set half their modems to -15dbm (for an output of -14dbm) and see what effect that has.
-- Aaron Nabil
-- Aaron Nabil - To unsubscribe to usr-tc, send an email to "majordomo@xmission.com" with "unsubscribe usr-tc" in the body of the message. For information on digests or retrieving files and old messages send "help" to the same address. Do not use quotes in your message.
We set a couple of HUBS to -13db and did not notice much of a difference our call fail rate is between 3% and 4% For example out of 235 calls taken 7 would fail.... This was about the same whether it was -11db/-12db/or -13db ============================================================================== Phillip Ferraro WorldNet Access, Inc pferraro@wna-linknet.com Onslow County's PREMIER InterNet Service Voice (910) 346-0835 824 Gumbranch Square, Suite R3 FAX (910) 455-1933 Jacksonville, Nc 28540-6269 ============================================================================== On Wed, 20 Oct 1999, Aaron Nabil wrote:
Greg Coffey writes...
Do you have a conclusion on this yet? Does changing these settings have any impact?
I haven't tried it yet, haven't been around the office much.
-a
At 04:46 AM 10/7/99 -0700, you wrote:
I call into our Max's and measured the level they were sending. Only -14dbm, much lower power, more what I was expecting. Telnet in and check to see what they are set to, -13dbm, another off by one, but this time in the opposite direction!
Here's a summary: Configured for Actually sends USR HiperDSP -11dbm -10dbm Ascend Max -13dbm -14dbm
I don't have any scripts in place that monitor failure ratios, but if someone does I'd be interested if they could set half their modems to -15dbm (for an output of -14dbm) and see what effect that has.
-- Aaron Nabil
-- Aaron Nabil
- To unsubscribe to usr-tc, send an email to "majordomo@xmission.com" with "unsubscribe usr-tc" in the body of the message. For information on digests or retrieving files and old messages send "help" to the same address. Do not use quotes in your message.
- To unsubscribe to usr-tc, send an email to "majordomo@xmission.com" with "unsubscribe usr-tc" in the body of the message. For information on digests or retrieving files and old messages send "help" to the same address. Do not use quotes in your message.
participants (7)
-
Aaron Nabil -
Brian -
Greg Coffey -
Kevin Benton -
Mike Andrews -
pferraro＠wna-linknet.com -
Richard Lorbieski