Kitz Forum
Broadband Related => ADSL Issues => Topic started by: jch on August 14, 2017, 12:23:49 PM
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My PlusNet ADSL connection has been rock solid for years. Last week, my connection started dropping randomly, sometimes several times a day and sometimes overnight. Network load wasn't a factor. Phone line tests showed no issues. PlusNet said they thought the problem was in my network. And sure enough, my router debug logs showed my router was terminating the PPP connection because the PPP peer had stopped replying to the router's LCP Echo requests. My router was therefore taking the connection down.
Suspecting a hardware issue, I swapped the modem out for a spare but the problem remained. On a hunch, I tried doubling the LCP Echo interval setting in the router. The link has now been up for several days with no drops whatsoever. Maybe a config change in the ISP network caused this change to be needed or maybe my LCP settings were too aggressive and it's just luck I've had no problems until now. I've no idea.
But this got me wondering. What are the recommended PPP LCP Echo settings for DSL connections. Any thoughts?
The PPP LCP defaults in the my router are:-
lcp-echo-interval 5
lcp-max-failure 6
lcp-echo-adaptive
The lcp-echo-adaptive setting means the router will only send new LCP Echo requests if no data is received from the peer since the last LCP Echo was sent. Thus my router sends LCP Echo requests more often when the connection is idle.
I doubled lcp-echo-interval to 10 and the connection is now stable. :)
My setup is an unlocked HG612, ADSL2, connected directly to a Ubiquiti Edgerouter-Lite which does PPPoE.
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An interesting question.
Not having any idea how my G.992.3 connection is configured, I took a look at a previously saved Wireshark session. I see that each end issues an LCP Echo Request approximately every 30 seconds.
The "A" end --
9 1.034920664 Dell_c1:20:9e PPP LCP 32 Echo Request
470 31.035905448 Dell_c1:20:9e PPP LCP 32 Echo Request
518 61.060214635 Dell_c1:20:9e PPP LCP 32 Echo Request
622 91.066676019 Dell_c1:20:9e PPP LCP 32 Echo Request
722 121.071766896 Dell_c1:20:9e PPP LCP 32 Echo Request
774 151.095087700 Dell_c1:20:9e PPP LCP 32 Echo Request
810 181.119396488 Dell_c1:20:9e PPP LCP 32 Echo Request
The "B" end --
366 7.705908487 JuniperN_ea:28:52 PPP LCP 66 Echo Request
472 36.881021477 JuniperN_ea:28:52 PPP LCP 66 Echo Request
540 66.882306927 JuniperN_ea:28:52 PPP LCP 66 Echo Request
628 96.881439171 JuniperN_ea:28:52 PPP LCP 66 Echo Request
724 126.882682316 JuniperN_ea:28:52 PPP LCP 66 Echo Request
776 156.882011863 JuniperN_ea:28:52 PPP LCP 66 Echo Request
812 186.883479411 JuniperN_ea:28:52 PPP LCP 66 Echo Request
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Sorry to dig an old topic up but I have been searching for this answer for months. Google found it I think, more testing is needed but I have swapped my internet detection to DNS probe instead of PPP echo as something must have changed on my ISP as I have seen no problems in months then all of a sudden the connection drops under 1gb load.
Edit: Apparently DNS probe isn't the answer it just dropped again.
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Sorry to dig an old topic up but I have been searching for this answer for months. Google found it I think, more testing is needed but I have swapped my internet detection to DNS probe instead of PPP echo as something must have changed on my ISP as I have seen no problems in months then all of a sudden the connection drops under 1gb load.
Edit: Apparently DNS probe isn't the answer it just dropped again.
Any reason to not just increase PPP echo timeout till it doesnt drop? I have an echo interval of 5 and failure threshold of 5, have had to do this for as long as I have had VDSL.
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Any reason to not just increase PPP echo timeout till it doesnt drop? I have an echo interval of 5 and failure threshold of 5, have had to do this for as long as I have had VDSL.
I set the interval to 10 and 6 threshold. But in a fit of rage I cancelled the diagnostics log run and turned the router into a wifi access point and my VMG1312-B10A modem into a router after a bit of configing everything seems snappier. Will monitor now to see if this has solved the problem.