Kitz ADSL Broadband Information
adsl spacer  
Support this site
Home Broadband ISPs Tech Routers Wiki Forum
 
     
   Compare ISP   Rate your ISP
   Glossary   Glossary
 
Please login or register.

Login with username, password and session length
Advanced search  

News:

Author Topic: recommended settings for ppp lcp echo interval?  (Read 10548 times)

jch

  • Just arrived
  • *
  • Posts: 14
recommended settings for ppp lcp echo interval?
« on: August 14, 2017, 12:23:49 PM »

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.
Logged

burakkucat

  • Global Moderator
  • Senior Kitizen
  • *
  • Posts: 31045
  • Over the Rainbow Bridge
    • The ELRepo Project
Re: recommended settings for ppp lcp echo interval?
« Reply #1 on: August 14, 2017, 09:57:40 PM »

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
Logged
:cat:  100% Linux and, previously, Unix. Co-founder of the ELRepo Project.

Please consider making a donation to support the running of this site.

banger

  • Kitizen
  • ****
  • Posts: 1053
  • TTB 80/20
Re: recommended settings for ppp lcp echo interval?
« Reply #2 on: September 02, 2020, 11:46:09 PM »

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.
« Last Edit: September 03, 2020, 12:38:46 AM by banger »
Logged
Tim
talktalkbusiness.net & freenetname
Asus RT-AC68U and ZyXEL VMG1312-B10A Bridge on 80 Meg TTB Fibre

https://www.thinkbroadband.com/speedtest/1502566996147131655

johnson

  • Reg Member
  • ***
  • Posts: 787
Re: recommended settings for ppp lcp echo interval?
« Reply #3 on: September 03, 2020, 01:20:54 AM »

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.
Logged

banger

  • Kitizen
  • ****
  • Posts: 1053
  • TTB 80/20
Re: recommended settings for ppp lcp echo interval?
« Reply #4 on: September 03, 2020, 03:49:10 AM »

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.
Logged
Tim
talktalkbusiness.net & freenetname
Asus RT-AC68U and ZyXEL VMG1312-B10A Bridge on 80 Meg TTB Fibre

https://www.thinkbroadband.com/speedtest/1502566996147131655
 

anything