airtel broadband: connection drops despite copper wire being changed!

[breakyo]

great that you have tested and found that DSL Link is not dropping. So there is no point of changing all the cables and wires. all are good enough.

Yes, I am very sure the DSL link on the modem doesn't flash when there is a disconnection.

Its more of a packet loss thats happening. Normally due to MTU this could happen for Yahoo Messenger and al. The yahoo messenger would get disconnected and connect back as its happening for various chat rooms.

Oh, I see. Well, actually I called up 121 once again this afternoon and I told about the disconnections, the customer care executive told me to go
http://59.144.47.27/ > then go to MTU Tools > then CMTU Tool > then download this tool > then load the CMTU Tool > then change the MTU value to 1454 in CMTU Tool Dialog box. [note : the MTU value before it was changed was lower, don't remember how much it was it was in the 1200's or 1300's]

The yahoo messenger would get disconnected and connect back

Well, I forgot to mention one thing to you, yahoo messenger has stopped disconnecting since 2-3 days, as far as i have observed. especially after the engineer changed some port at the exchange 2 days back. but there are disconnections in some chat rooms which i visit regularly.

With the model number of your modem I dont think there is an option to set mtu on the modem itself. With the model number of your modem I dont think there is an option to set mtu on the modem itself.

yes you are right, i tried searching for MTU option, and couldn't find it.

You would need to change the same on your computer.

I think the MTU value has been changed to 1454, is this the same MTU value are you talking about?.

Again now to identify if there is a packet loss on the network or is it due to just mtu issue you can probably run a continuous ping.

on command prompt - run a continous ping to some site like google or so.

ping google.com -t

as soon as I read this I did a ping google.com -t on command prompt and noticed 4-5 'Request timed out' messages in between the replies withing first few minutes.
I also did a ping on other two chat sites ( didn't open the chat sites while pinging) in which I used to get disconnected, the same 'Request timed out' messages appeared in between replies to the ping within first few mins.

Just check if there is a packet loss during the time when you loose the connection to MEssenger and chat rooms.

So I should check the replies to ping only when I loose the connection to a particular chat room? what if there is packet loss ( does 'Request timed out' mean packet loss? ) at other times.

How to Optmize your MTU ?
https://www.dslreports.com/front/DRTCP021.exe

Download the tool from the above link. First set the MTU on your adapters to 1500.

Now try ping a wesbite with packet size of 1500-28

ie.
ping google.com -l 1478 -f

if you are getting a reply then the mtu is ok, else if its says packet needs to be fragmented then you need to reduce the value of 1478 to lower. Keep lowering in and find the optimum value. SO if you get a reply at 1460 and at 1461 it says packet needs to be fragmented then your MTU size should be 1460+28=1488 and this needs to be set for your adapters.


You can even find how to optimize the MTU if you search through in google.

I am a bit confused now, the current value entered under MTU value in CMTU tool is 1454. so what do i do now? go ahead with downloading the tool from the website you have given and change the values?

But atleast now you can ask AIRTEL to stop working on cables and splitters. Its clearly nothing wrong with it. Even a modem change may resolve the issue. The reason the modem may not be auto negotiating the MTU.

well, 2 days back the local tech had called and informed that net would be down for 30 minutes, upon asking why? He said he is changing some port at the exchange. after this no lines or cables have been changed. also this morning i made a request for a change of modem and splitter, and I was told it would be arranged.

Also do let me know if you are finding it confusing. I will explain you.

well. not much confusing, you have explained it well, though i am yet to do the googling part and understand how to optimise MTU.

thank you very much for explaining in detail and step-by-step. .


screenshot :



----------

Hey AjayJp. I actually followed the steps you mentioned to find out the optimum MTU and also followed the guide at How do I optimize my MTU and RWIN settings? DSL FAQ - dslreports.com. and to my surprise, the optimum MTU turned out to be 1454, the same MTU number which the customer care executive had told me to enter in the MTU values! lol.

by the way, there are 2 computers connected to the router, one - laptop and two - desktop. I have changed MTU value in both.

Again now to identify if there is a packet loss on the network or is it due to just mtu issue you can probably run a continuous ping.

on command prompt - run a continous ping to some site like google or so.

ping google.com -t

what error would it show if there is a packet loss?

.

 

[coimby]

Can you please post ping results here? Also, please ping to "www.yahoo.co.in".

So,
1) Run 'ping -l 1454 -f -n 50 www.yahoo.co.in'
Run 'ping -l 1455 -f -n 10 www.yahoo.co.in'

2) Run 'ping -n 50 www.yahoo.co.in'

3) Run 'tracert www.yahoo.co.in'

Send results for the above.

 

[AjayJP]

The MTU whatever the AIRTEL executive asked you to change is exactly what I was telling you. You did not tell us if the issue has solved, I mean disconnections from Chats.When your MTU is set to 1454 in your computer, you need to ping with packet size 1454-28=1426. So if you ping ping google.com -l 1426 -f it should give a reply ( pls try with google itself and not with your chat servers)If you ping with 1427 it would say packet needs to fragmented. But since you have set to 1454 you will not know if the optimal MTU size is more than that. So if you set to 1500 and keep lowering till you get the optima. But since you have currently set to 1454 check out if your issue is solved.Else next you can set the MTU to 1460 and check for your disconnections.Then when you say with a normal continuous ping to google.com itself is giving you high packet loss then there is some serious concern. But can you confirm if the loss is similiar on all other computers connected to this modem. (ping google.com -t) random 1 drop would be ok. But as you say 3-4 continous drops is of concern. I would like to know if this loss is restricted to 1 computer or on all computers next,

 

[coimby]

Hi AjayJPWhat is 28 in '1454-28' ? Thanks.

 

[AjayJP]

28 is the size of IP Headers that gets added to your data packet. So MTU is size of packet thats going to be sent. So when its 1500 the actual data that is being sent is only 1454-28

MTU Ping Test

 

[breakyo]

How to Optmize your MTU ?
https://www.dslreports.com/front/DRTCP021.exe

Download the tool from the above link. First set the MTU on your adapters to 1500.

Now try ping a wesbite with packet size of 1500-28

ie.
ping google.com -l 1478 -f

if you are getting a reply then the mtu is ok, else if its says packet needs to be fragmented then you need to reduce the value of 1478 to lower. Keep lowering in and find the optimum value. SO if you get a reply at 1460 and at 1461 it says packet needs to be fragmented then your MTU size should be 1460+28=1488 and this needs to be set for your adapters.

I followed these steps once again, 1464 is the optimum value, and i get a reply at 1464 and at any number above that it says packet needs to be fragmented, so my MTU size should be 1464 plus28 equals 1492. right?. I have set it in adapter to 1492. but when I ping google.com -l 1492 -f it ssays packet needs to be fragmented.

the above steps have been done in laptop ( windows vista) which is connected wirelessly to the router.

now doing the same steps on my desktop (windows xp) :

1426 is the optimum ping. and any number above that it says packet needs to be fragmented, so the optimum MTU size for my desktop is 1426 plus 28 = 1454. right?

----------

Can you please post ping results here? Also, please ping to \"www.yahoo.co.in\".

So,
1) Run 'ping -l 1454 -f -n 50 Yahoo! India'
Run 'ping -l 1455 -f -n 10 Yahoo! India'

2) Run 'ping -n 50 Yahoo! India'

3) Run 'tracert Yahoo! India'

Send results for the above.


----------

[/COLOR]The MTU whatever the AIRTEL executive asked you to change is exactly what I was telling you. You did not tell us if the issue has solved, I mean disconnections from Chats.

When your MTU is set to 1454 in your computer, you need to ping with packet size 1454-28=1426. So if you ping

ping google.com -l 1426 -f it should give a reply ( pls try with google itself and not with your chat servers)

If you ping with 1427 it would say packet needs to fragmented. But since you have set to 1454 you will not know if the optimal MTU size is more than that. So if you set to 1500 and keep lowering till you get the optima. But since you have currently set to 1454 check out if your issue is solved.



I changed the value to 1500 from the 1454 in the desktop and laptop and optimum MTU size in both are 1426 and 1464 respectively. so i have added 28 to each of these numbers and set it in the The MTU size.

please tell me how to know if there is a packet loss? what error message does it show?

 

---

[AjayJP]

Monitor your disconnection issue now. Check and let me know if the connections are dropping still .You can also run a continous ping .. ping google.com -t and if your connection to chat rooms break check if the ping is giving a request timed out at the same moment.Also you can have a ping to your chat server in a differnet window too.. so again if there is a disconnection and you see drops on both pings then there is packet loss.. but if its only to your chat server and not to google.com then it could be a loss in the route to the chat server which there is very less we could do to solve.But if yahoo messenger has stopped disconnecting and you do not have any disconnections in VPN(if in case you use anything) then all is good

 

[coimby]

I followed these steps once again, 1464 is the optimum value, and i get a reply at 1464 and at any number above that it says packet needs to be fragmented, so my MTU size should be 1464 plus28 equals 1492. right?. I have set it in adapter to 1492. but when I ping google.com -l 1492 -f it ssays packet needs to be fragmented.

the above steps have been done in laptop ( windows vista) which is connected wirelessly to the router.

now doing the same steps on my desktop (windows xp) :

1426 is the optimum ping. and any number above that it says packet needs to be fragmented, so the optimum MTU size for my desktop is 1426 plus 28 = 1454. right?[COLOR=\"Silver\"]

----------

[/COLOR]

RESULTS :

1) ping -l 1454 -f -n 50 Yahoo! India



ping -l 1455 -f -n 10 Yahoo! India


2) pig -n 50 Yahoo! India



3) tracert Yahoo! India

[COLOR=\"Silver\"]

----------

[/COLOR]


I changed the value to 1500 from the 1454 in the desktop and laptop and optimum MTU size in both are 1426 and 1464 respectively. so i have added 28 to each of these numbers and set it in the The MTU size.

please tell me how to know if there is a packet loss? what error message does it show?

Hi breakyo,
For the purpose of troubleshooting, please perform all tests only from the desktop. May I ask from where you did the ping tests I requested?

Also, please run the following from your desktop:-

1) ping -l 1464 -f -n 50 Yahoo! India
ping -l 1465 -f -n 50 Yahoo! India

2) And let us know with what MTU setting on your desktop that you ran the above tests.

Post results again .

 

[breakyo]

Monitor your disconnection issue now. Check and let me know if the connections are dropping still .

You can also run a continous ping .. ping google.com -t and if your connection to chat rooms break check if the ping is giving a request timed out at the same moment.

Also you can have a ping to your chat server in a differnet window too.. so again if there is a disconnection and you see drops on both pings then there is packet loss.. but if its only to your chat server and not to google.com then it could be a loss in the route to the chat server which there is very less we could do to solve.

But if yahoo messenger has stopped disconnecting and you do not have any disconnections in VPN(if in case you use anything) then all is good

Hi, there. . yes sure thing. will monitor the disconnection issue now. as soon as i read this post of yours yesterday, I started continous pinging of google.com and the chat servers and I chatted for some 30 minutes last night. there was no disconnection, though I saw more than a couple 'request timed out' messages in both google and chat server pings.

will have to monitor it for a couple of days more to be sure if there is 'request timed out' messages, when I get disconnections from the chat.

and yes yahoo messenger has stopped disconnecting, and my brother who watches a lot of lengthy youtube videos on the laptop says, there is no buffering or disconnection while watching them. I don't use VPN, i may have to google to know what it means, I am sure I don't use this service.

thank you once again will write back to you right away after monitoring the disconnections for a day or two.

have a merry weekend

----------

Hi breakyo,
For the purpose of troubleshooting, please perform all tests only from the desktop. May I ask from where you did the ping tests I requested?

Also, please run the following from your desktop:-

1) ping -l 1464 -f -n 50 Yahoo! India
ping -l 1465 -f -n 50 Yahoo! India

2) And let us know with what MTU setting on your desktop that you ran the above tests.

Post results again .

Hi, coimby. . ok will perform all tests now on desktop and post the results once again. by the way, I am sure there is a way ( some command?) to post the ping replies into a text file from command prompt, instead of taking screen grabs.

May I ask from where you did the ping tests I requested?
I opened the command prompt on the laptop( windows vista) which is wirelessly connected to the adsl2 + router ( the router is right next to the lappy).

2) And let us know with what MTU setting on your desktop that you ran the above tests.

the current optimum MTU setting on the desktop is set to 1454 and on the laptop is 1492.

will post the results this evening.

 

[AjayJP]

- As your yahoo is not disconnecting and youtube not buffering shows that the MTU has really worked. Anyways keep your fingers crossed.- 1 or 2 request timed out at random should be ok. But if there is a conitnous timed out for both google and your chat servers would be a concern. ANyways keep monitoring them till you declare your issue resolved.- In your command prompt window, if you right click you will get an option as Mark. You can now select the ping results you want to copy and just press enter to copy. You can then paste into anywhere are text rather than screenshotsKeep us posted about your connection. We would be happy to know if this has resolved the issue after a long struggle with your service provider.