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Author Topic: Reconnecting routers and rebooting routers  (Read 5332 times)

supercooper

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Reconnecting routers and rebooting routers
« on: July 02, 2008, 02:21:43 PM »

Hi Guys,

I work with a Telecoms company on the Broadband support desk, im not the most technical person in the world but im interested on how things work.

We supply IPDC which is VOIP using a telephone system and a Router.  I have noticed on some connections with problems that the Router we supply (Draytek Vigor2800) will re-connect by it's self and continue to do this and on other connections the customer will have to manually re-boot the router for the connection to come back up.

If I tell BT that the customer has to manualy re-boot the router, they will always say that the Router is faulty???  I'm wondering how they always come up with this answer.   

Also in regards to the connections that do drop and log straight back in they nealry always blame this on "user request" I know that some of the connections have a low error rate and a good SNR but cannot confirm loss of sync on most occasions due to the placment of the router.

Another thing i think maybe related is i have read somewhere if the Router is passing a huge amount of traffic with high errors they Draytek will try to resync to kick out the errors.  Can anyone confirm this or provide info that will help me out with diagnosing these type of problems?

We do not use the Routers internal VOIP as the telephone systems have the cards to manage this so affetivley the router is only used for passing traffic via several open ports to the phone system.

Also i would like any feedback on routers that are known to handle poor quality lines and low SNR signals.  I can request any router and will be happy to supply you guys any info so we can see how each router will handle poor connections once live.

Thanks in advance for your responses.

Chris :)
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kitz

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Re: Reconnecting routers and rebooting routers
« Reply #1 on: July 02, 2008, 08:48:23 PM »

>> re-connect by it's self and continue to do this and on other connections the customer will have to manually re-boot the router for the connection to come back up.

I've seen this before, and its been discussed on these forums before by several people.  In fact Ive even seen it occur on my own line with a different router.  I've seen someone blame the ISP, but then move to another and the problem just followed.

My own (unproven) theory is that it may be either to do with the type of equipment in the exchange or at the RAS.  Reason being that it first happened to me (with a Voyager 2100) after I'd been reRASed a few years ago.  The problem went away entirely on its own accord about a year later.. which would have co-incided to about the time BT installed some new MSANs in our exchange.

I believe its more likely to occur when just the PPP session is lost (The later part of the connection to the ISP) rather than full loss of sync.

>> Another thing i think maybe related is i have read somewhere if the Router is passing a huge amount of traffic with high errors they Draytek will try to resync to kick out the errors.

No It will loose sync when the SNR is too low for the router to "hear" the signal properly.
Errors could be taken as being an early warning that the SNR is getting too low and is the equivalent of the router saying "pardon - can you repeat that please".

Thats the simple version, the reality is there's different types of errors, some of which are reported on some, but not all routers.  The errors recorded by most routers are FEC/HEC/CRC, which are in effect the least severe..  the more severe error states are things like OOCD or LOF which leads up to an LOS.. which may lead to a full resync
If the router doesnt display these events, then you should be looking at the no of errored seconds over x period of time. The connection should be able to cope with occasional errors, but it will loose sync if there's a high burst of errors together. (eg too many CRCs in a time frame will be the trigger for one of the error state processes.. then 10 SES's will cause loss of sync). (More info on the types of errors and error states ).


>> Also i would like any feedback on routers that are known to handle poor quality lines and low SNR signals.

hmmm  bit of a hard task..  there are some routers which are known to handle poor quality lines.  Some work better on some lines, whilst others work better on others.
For example some Netgears (DG834Gv4) are known to hang on well to long lines, whilst Speedtouch routers hang on well on others.  Other routers worth looking at 2Wire and Roseways had success with the Billion 5200G.

When youre talking about poor quality - does that mean long lines with low sync speeds, or lots of SNR fluctuation?
Im also thinking that because of the VoIP element lots of errors aren't going to be too good as quality of call would be an issue so perhaps a router that can be tweaked to allow a higher Target SNR for stability. Im not well up on "true" VoIP so maybe others can comment.
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supercooper

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Re: Reconnecting routers and rebooting routers
« Reply #2 on: July 03, 2008, 11:20:46 AM »

Hi Kitz,

Thanks fist of all thank you for you reply.

I agree your theory on re-connecting routers does appear to be the most logical one.  As you know we supply VOIP to many of our customer and some are on long lines with low SNR's and with high error rates.  In most cases we have reduced the speed of the connections to our customers sites to improve the signals and reduce the amount of errors passing.  On some sites they require a high amount of voice paths so this cannot always be done to rectify the problems we so frequently walk into.

As it happens we do supply the Netgear 834G v4 for our data custmoers, so today i will configure one of these Routers for one of our phone systems and try it out on one of our problematic sites.  So far i have compared the Draytek Vigor 2800 with the Netgear on our own connection and the SNR did increase by 1.5db on the same profile.

I intend to source some 2 wire routers also and give them a go to see how they handle poor connections etc. 

I have read about a router somewhere that was tweaked to change the SNR via the router instead of BT setting the profile, maybe i am wrong here as it was some time ago i think it was a speed touch but i cannot fully rememeber.  If i can find one of these i will certainly give it a try.

In regards to errors and the differant type i didnt really look into this much so i fully intend to read up on this also to get an idea on more things to look for during the tests i will be conducting.

Thanks again, Chris
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roseway

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Re: Reconnecting routers and rebooting routers
« Reply #3 on: July 03, 2008, 11:44:02 AM »

Quote
I have read about a router somewhere that was tweaked to change the SNR via the router instead of BT setting the profile, maybe i am wrong here as it was some time ago i think it was a speed touch but i cannot fully rememeber.  If i can find one of these i will certainly give it a try.

There are several routers which can be tweaked using the DMT tool. If you look down that page you will see each version listed, together with which routers it supports. Don't worry that it's in German - the DMT program offers English as an option when you run it the first time.

DMT can't set the target noise margin directly, but can only offset the value set in the exchange by about +/- 6 dB. And do note that recent versions of the Speedtouch firmware have had the capability to tweak the margin removed from them. See this page and this page for more information.
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kitz

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Re: Reconnecting routers and rebooting routers
« Reply #4 on: July 03, 2008, 01:12:46 PM »

Quote
I have read about a router somewhere that was tweaked to change the SNR via the router instead of BT setting the profile, maybe i am wrong here as it was some time ago i think it was a speed touch but i cannot fully rememeber.  If i can find one of these i will certainly give it a try.

Yes the speedtouch - but do be very careful the function is blocked in the newer models and newer firmware versions.

>>> we do supply the Netgear 834G v4


the Netgear 834G v4 is DMT tweakable. :)
The only problem is, that unlike with the STs its not a permanent save feature and has to be reapplied :/
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supercooper

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Re: Reconnecting routers and rebooting routers
« Reply #5 on: July 04, 2008, 11:10:39 AM »

Hi Guys,

I tried the Netgear 834G v4 on our own VOIP connections and the call quality was terrible :(  I will have to stick to the Draytek Vigor for now. 

I'm goiong to source a 2Wire next and give that a go.

Thanks, Chris
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kitz

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Re: Reconnecting routers and rebooting routers
« Reply #6 on: July 04, 2008, 11:20:50 AM »

>> I tried the Netgear 834G v4 on our own VOIP connections and the call quality was terrible

:(

Just out of interest what was the SNRM like?  (wondering if there were any errors showing)
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supercooper

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Re: Reconnecting routers and rebooting routers
« Reply #7 on: July 07, 2008, 10:35:54 AM »

Hi Kitz,

The SNR on the Draytek is a steady 6db and on the Netgear it was showing as 8.1db (Downstream).

We used two telephone systems, an IPLDK 100 and and NEC XN-120.  the call quality was distorted an had an echo using the Netgear router :(  QOS was switched off on the Draytek to make it a fair test. 

I ran a QOS test using our providers site >>> http://speedtest.gammatelecom.com/
No paket loss and the QOS came in between 70-80% on several tests, we are close to the exchange so we had no speed issues.

Oh just a thought i know the Netgear has hidden pages im wondering if there is a hidden QOS setting i can play with? 

Today i hope to play with this some more so i will keep you posted on any interesting findings :)

Thanks, Chris

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kitz

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Re: Reconnecting routers and rebooting routers
« Reply #8 on: July 07, 2008, 12:17:43 PM »

>> the call quality was distorted an had an echo using the Netgear router

Damn :(

I dont know about QoS on the dg834gt Im afraid as its not a router Ive ever had chance to play around with.
Since its based on the same chipset as the Voyager 2100 series, which does have QoS, then the ability to enable it must be there somewhere deep in the router, but whether or not it accessible I dont know :/
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supercooper

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Re: Reconnecting routers and rebooting routers
« Reply #9 on: July 25, 2008, 03:32:09 PM »

hi Guys,

Just to let you know ive decided on using a LinksysAG241 Router.

So far i have tested this as ok with only a few echo's so far.  I was using ping plotter to track the latancy which was coming in at around 40-60ms.  I still dont think we should be getting an echo tranfering 30kbps both ways on the system i am using with the codec set at G729.

I have requested Bt remove Interleaving from our line to see how this affects the testing we have conducted.

Next week i should have an update for this, and if all proves well i can send these to a few problematic sites to see how the connection holds on this router, my hopes are high as they are CISCO :)

Thanks, Chris
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kitz

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Re: Reconnecting routers and rebooting routers
« Reply #10 on: July 25, 2008, 04:03:31 PM »

Good luck with the linksys' hope all goes well
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supercooper

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Re: Reconnecting routers and rebooting routers
« Reply #11 on: July 30, 2008, 03:35:03 PM »

Just to keep you posted, i spoke to a BT Engineer yesterday about routers that fail to reconnect without a re-boot, he told me 90% is due to port error at the exchange when this occurs the other 10% can be a filtering issue.

Not sure how true those comments are but its worth taking this into account i guess.

Thanks, Chris
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kitz

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Re: Reconnecting routers and rebooting routers
« Reply #12 on: August 01, 2008, 12:50:08 AM »

>> , he told me 90% is due to port error at the exchange when this occurs the other 10% can be a filtering issue.

Interesting - thanks for that info.

Whether or not that ties into when Ive seen it occur on my own router Im not sure.
- mine occured after I'd been reRASed by BT...  and disappeared around the time I got moved to an MSAN, so its possible.

However it wouldnt explain why in my own instance that it was ok if I used another router, during that period.
Yet the router that played up with that fault suddenly started working again.

Now I put it down to being reRAS'd (Manchester <-> Kingston)..  bearing in mind that a reRAS often means a different dslam/msan - which would mean a different port on the line card - there well could be something in what he says.
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