marc1
join:2003-12-10
|  SPA-2102 slows my internet connection
Howdy crew.
Just noticed that my Sipura SPA-2102 really slows down my internet connection.
I did a speed test with computer plugged directly into my modem and another with SPA-2102 in between.
When the Sipura is being used, I get about half the throughput.
Any thoughts? |
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Dan_voip
join:2007-01-03
Canada | Might be QoS setup who is reserving to much of bandwidth for VoIP. I don't have this adapter but I was reading about changing QoS policy from "always on" to "on when phone in use". |
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userofdsl
join:2000-07-31
Brighton, MA
2 edits | reply to marc1
Previous posts here and elsewhere warn that SPA devices, although they are good ATAs, do not function well as routers, and it is best to use only their ATA functionality, and a separate high-quality router. You would connect the router to your broadband modem, and the PC and the SPA2102 to separate ports on the router. If you need QOS, make sure the router can provide it. |
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OmagicQ
join:2003-10-23
Bakersfield, CA | reply to marc1
Is the issue with SPA devices the lack of sufficient cpu power for handling calls AND pppoe/NAT/Routing/etc? I would think that Linksys would have designed the ATAs with router functions well enough to do both jobs. |
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mgraves1
join:2004-04-05
Houston, TX | reply to marc1
Nobody can answer your question well without also knowing your data rates. If your connection is slow then even simple, correct traffic shaping provisions will appear to impact your available bandwidth.
Michael |
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marc1
join:2003-12-10 | With SPA: 7.39 Mbps (down)
Without SPA: 12 Mbps (down) |
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mgraves1
join:2004-04-05
Houston, TX
 ·Junction Networks
| reply to marc1
I suspect that there may be issue with some ATAs that also provide a QoS/traffic shaping function. Their design may not have considered the faster internet connections that are more recently available.
For example, there are common consumer routers that have been widely used that simply cannot cope with the kind of bandwidth offered on faster cable modem connections. Mostly these are older devices, but it's possible.
OTOH, if you are only passing a couple of calls at a time you may not need the QoS provisions of the ATA given the speed of your connection. That may have more to do with what else is using your bandwidth. For example, if you use peer-to-peer file sharing you might still need QoS capability to keep the voice traffic getting priority over the torrents.
--
Michael Graves
Houston TX
»www.mgraves.org |
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marc1
join:2003-12-10 | I am not sure how to configure QOS on the 2102. I am not even sure it lets you do it. |
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mgraves1
join:2004-04-05
Houston, TX | So don't put the device in between everything else and your router. Hang it on the network like any other device. See if that works out better for you. |
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Arne Bolen
join:2009-06-21
Denmark | reply to marc1
The SPA-2102 has a speed limitation of 7500Kbps both up and down, this a hardware limitation. |
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marc1
join:2003-12-10
| Thanks Arne. That would make sense. I came across this
»forums.linksysbycisco.com/linksy···.id=3793
which corroborates your comment.
Curious how you heard about that limitation? Do you have a link you can point me to? |
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Arne Bolen
join:2009-06-21
Denmark
·Callcentric
·voip.ms
| said by marc1  :Curious how you heard about that limitation? Do you have a link you can point me to? I read about the limitation 2-3 years ago when I tried to find out why my SPA-2102 limited my download speed to around 6500 Kbps, I can't remember where I read it.
Now I use SPA-962 and Gigaset S685IP on a ZyWALL 2WG so I don't have any speed issues anymore.  |
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DogFace05
join:2005-12-09
Cary, NC
| reply to Arne Bolen
said by Arne Bolen :The SPA-2102 has a speed limitation of 7500Kbps both up and down, this a hardware limitation. This is nothing but utter baseless nonsense. There is no such hardware limitation, period. The only thing that limits the throughput of the SPA2102, while in non-bridged mode, are its host processor and software's ability to keep up with the IP/ethernet traffic and perform routing tasks, shuffling data back and forth between the two ports, while simultaneously having to take care of a whole host of other duties (including, in particular, voice processing). (In bridged mode, all communication between the ethernet ports are switched in hardware at full speed, without any involvement of the processor.)
The SPA2102 was intended and designed to be primarily a low cost ATA, not a full-fledged router. Its routing function is only secondary, and meant just for the kind of light duty routing (such as email and web browsing) that might typically be required by people on the road (eg, while staying in a hotel) and those who do not have another router and do not need the performance of a dedicated one, so they can connect their laptop behind the SPA2102, and still use both while yet having some measure of firewall protection. It is not, and never has been intended to replace a good standalone router. |
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Arne Bolen
join:2009-06-21
Denmark
·Callcentric
·voip.ms
| I consider the processor to be part of the SPA-2102 hardware thus I consider it as a hardware limitation. If you do not believe the processor is part of the SPA-2102 hardware it is fine, however I am sure most people think the processor is part of the hardware. |
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Sly
Premium
join:2004-02-20
Johnson City, TN
clubs:
·Packet8
·Callcentric
 ·Comcast Formerly ..
1 edit | reply to marc1
Long story short, unless you NEED it to function as a router, I would just put it behind your network as another device (as has already been mentioned).
Should be Modem, router, and then everything else hooked to the router.
Before you do this, however, in order to still access the web settings you need to log onto as administrator, advanced... and then go to WAN setup. Give it a static ip address if you prefer and then change Enable WAN Web Server: to "yes". Submit changes.
--
"The penalty good men pay for indifference to public affairs is to be ruled by evil men."
- Plato - |
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marc1
join:2003-12-10 | reply to marc1
thanks for all the feedback. i picked up a router and now using the 2102 as just a ATA. Speeds are now where they should be. |
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DogFace05
join:2005-12-09
Cary, NC
| reply to Arne Bolen
said by Arne Bolen :I consider the processor to be part of the SPA-2102 hardware thus I consider it as a hardware limitation. If you do not believe the processor is part of the SPA-2102 hardware it is fine, however I am sure most people think the processor is part of the hardware. The hardware limitation for a given task is the best performance that can be had from a system of hardware and software, when all factors attributable to software are fully optimized and impossible to streamline any further. This implies having the host processor perform NO OTHER TASKS other than the ONE task for which we are trying to determine a performance ceiling. In the case at hand, it means having the processor ONLY do reading and immediate retransmission of ethernet packets through its ethernet controller's ports, and NO OTHER TASKS at all. This establishes a measure of the hardware imposed throughput limit. Any inferior performance observed during normal operation, is strictly due to software imposed overhead, and thus software limitations--not hardware limitations, as you would have people incorrectly believe.
The SPA2102's particular processor and ethernet controller (Micrel KSZ8842), due to certain differences in their individual I/O bus architectures, do impose a less than ideal throughput limit (yes, a hardware limit), when reading and writing packet data from/to the controller. However, this limit (which results in a routing throughput ceiling of just under 60 Mbps) is far higher than, and not even in the same ballpark as the faux hardware limit you're arbitrarily claiming based on not even a shred of factual basis.
The ~6-7 Mbps limit that people report observing, is plain and simply the result of software overhead. Any time that a system's performance can be improved by optimizing or improving its software, we consider its performance limited by software, not hardware. To illustrate how sensitive the SPA2102 is to software overhead, just put some significant load on it, such as running two simultaneous G.729 calls, and watch its routing performance degrade dramatically further. |
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