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Anonymous
(Unregistered)Mon 04-Apr-11 23:17:56
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Packet loss when running 2 broadband connections


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I have 2 telephone lines recently installed. The local exchange offers only ADSL max but is unbundled.

Setup:

1. Line 1 with O2 BE and ISP provided router 1.
2. Line 2 with BT ADSL and same ISP provided router 2. This is the failover.

With router 1 on, and router 2 powered off, laptop connected directly to LAN side of router 1, I can connect to the internet with no packet loss.

With router 2 on and router 1 powered off, laptop connected directly to LAN side of router 2, I can also connect to the internet with no packet loss.

With router 1 on and router 2 powered on, laptop connected directly to LAN side of router 1 and nothing connected to LAN side of router 2, I have an average say 60 percent packet loss making internet surfing impractical. There is no lead between either router. Simply they are both powered on at the same time.

The ISP says its a configuration problem with my setup. I am stumped by what this could be. Any help much appreciated.

Dave
Standard User XRaySpeX
(knowledge is power) Mon 04-Apr-11 23:34:56
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Re: Packet loss when running 2 broadband connections


[re: Anonymous] [link to this post]
 
confused Puzzling setup!

What routers are they?
How does PC know which router to connect to?
Is it by wireless?
Do routers have diff SSIDs?
Are routers on well separated channels?

1999: Freeserve 48K Dial-Up => 2005: Wanadoo 1 Meg BB => 2007: Orange 2 Meg BB => 2008: Orange 8 Meg LLU BB => 2010: Orange 19 Meg Tweaked / 16 Meg Untweaked LLU BB
Standard User blueacid
(committed) Mon 04-Apr-11 23:41:42
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Re: Packet loss when running 2 broadband connections


[re: Anonymous] [link to this post]
 
OK, this might take you 10mins, but can you (with ethernet cable connection) get the line stats from each router (and a quick visit to speedtest.net & pingtest.net) with:

1) o2 only on
2) BT only on
3) & 4) Both routers on, check either of them.

Also, you might like to try the quiet line test with all the 4 testing scenarios above: The quiet line test is achieved by dialling 17070 then choosing option 2. The telephone line should be silent; devoid of crackles, hiss, buzz etc. If any combination of routers can cause a buzz or crackle on the line then that's well worth investigating.

Cheers,
Blueacid
=================================
Was on Xilo C&W LLU on MRCEN, Now Be* on MRARD.


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Standard User RobertoS
(sensei) Mon 04-Apr-11 23:57:12
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Re: Packet loss when running 2 broadband connections


[re: Anonymous] [link to this post]
 
How are the routers connected to the landlines, and where are the two master sockets? How close together are the routers and their mains plugs?

My broadband basic info/help site - www.robertos.me.uk
My domains,website and mail hosting - Tsohost. Internet connection - IDNet Home Starter Fibre. Live BQM.
Administrator MrSaffron
(staff) Tue 05-Apr-11 09:22:27
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Re: Packet loss when running 2 broadband connections


[re: Anonymous] [link to this post]
 
Is wireless disabled on both of them and the laptop? Just to ensure its wireless card is not creating issues jumping between the two.

Try the testing with router 1 on and connected, but router 2 on but not connected to the phone line and vica versa

Also for each of the combinations go and get the ADSL line stats.

Are you using extension leads, or just the master socket.

Andrew Ferguson, andrew@thinkbroadband.com
www.thinkbroadband.com - formerly known as ADSLguide.org.uk
The author of the above post is a thinkbroadband staff member. It may not constitute an official statement on behalf of thinkbroadband.
Anonymous
(Unregistered)Wed 06-Apr-11 08:23:28
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Re: Packet loss when running 2 broadband connections


[re: MrSaffron] [link to this post]
 
Thank you for your replies. Both routers are wired only.

Further discussions with the ISP suggest a reason.

A block of public IP addresses are routed to both broadband connections. Initially I tested failover using a draytek 2920n and 2 x vigor 120s to bridge PPPoA to PPPoE. This proved problematic with the 2920n unable to start the BT line on WAN2 upon disconnecting the primary o2 line on WAN1.

So to test the lines I setup the posted configuration above, using the provided routers. I am told this causes the packet loss due to the provision of the same block over both lines requiring a router capable of handling this. I'm guessing that the 2920n does not support some aspect of the provision of public ip addresses over both lines.

Dave
Standard User WWWombat
(member) Wed 06-Apr-11 08:43:51
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Re: Packet loss when running 2 broadband connections


[re: Anonymous] [link to this post]
 
Overall, you have to find out where the packets are going missing. It could be on the ISP side, over the ADSL, or on your internal network/subnets.

What do you mean by "failover"? That something automatic is happening? Or are you just unplugging an ethernet cable from one router to the other? I just wonder, because the recent post sounds automatic, while the original sounded manual.

When you say "packet loss", what kind of packets go missing? Are you just running pings to the routers? Or out over the internet? Or are you expecting a TCP session (eg telnet, FTP or HTTP) to continue when the failover happens?

What are the IP subnets your two routers are running internally? Same or Different? Which manages DHCP?

When you say "A block of public IP addresses are routed to both broadband connections", does that mean they both get the same block of IP addresses? How does this work with 2 different ISPs at the end of each line?

Things I can think of that might cause this:
- Trying to keep a TCP session alive when the external IP address has changed
- Problems in talking to a second router with the same IP address, caused by MAC address confusion
- Crosstalk interference of the 2 ADSL lines, causing lots of CRC errors, and long delays in packet transmission - possibly seen as dropped packets.

How likely any of these are depends on exactly what you are trying to do - and that isn't very clear.
Anonymous
(Unregistered)Wed 06-Apr-11 09:20:39
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Re: Packet loss when running 2 broadband connections


[re: Anonymous] [link to this post]
 
A block of public IP addresses are routed to both broadband connections. Initially I tested failover using a draytek 2920n and 2 x vigor 120s to bridge PPPoA to PPPoE. This proved problematic with the 2920n unable to start the BT line on WAN2 upon disconnecting the primary o2 line on WAN1.


If you have a single block of IP addresses being routed to both lines, as intended for failover, this would explain it.

Failover means exactly that. The setup is intended to Fail Over from Line 1 to Line 2 and is only designed to have one active at any one time. If you activate both lines at the same time, it is likely trying to send 50% of the packets to line 1, and 50% to line 2 as the BRAS at the ISP end will be seeing two connections with the same IP addresses.
Anonymous
(Unregistered)Thu 07-Apr-11 23:15:33
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Re: Packet loss when running 2 broadband connections


[re: Anonymous] [link to this post]
 
You are right about the cause. Is it not ironic that the setup I put in place to test the 2 lines actually created another issue?

Still no further forward with Draytek 2920n. Its failover mode seems incompatible with 2 lines with a block of IP addresses routed over both.

Thanks to everyone for answering.

Dave
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