Keep Alive setting

All about firmwares for routers. Support for RouterTech firmwares is here too.
Post Reply
boomer
Novice
Novice
Posts: 13
Joined: Wed Jan 15, 2014 5:45 pm

Keep Alive setting

Post by boomer » Wed Apr 29, 2015 12:57 am

I'm a bit confused about the explanation given in the PPP Connection help page about the Keep Alive setting:

"Keep Alive: When on-demand option is not enable, this value specifies the time to wait without being connected to your provider before terminating the connection. A non-zero value."

How can the connection be terminated when there is no connection? Is this not a redial period for when a connection is terminated by the provider? Any clarification would be appreciated.
boomer
Novice
Novice
Posts: 13
Joined: Wed Jan 15, 2014 5:45 pm

Re: Keep Alive setting

Post by boomer » Thu Apr 30, 2015 12:04 pm

https://www.juniper.net/techpubs/en_US/ ... alive.html
http://rbdoc.ufanet.ru/enlzn78300111r2/ ... CHAPTER1.5

From what I understand on these pages, with the data check option enabled, the router will send an LCP echo request to the provider when the timeout period expires if no data was received within the timeout period, to determine if the PPP session is inactive. If no data or reply is received between 3-4 timeouts (failed timeouts) the PPP session is terminated. With the data check option disabled the router will send and LCP echo request after the timeout period expires regardless of whether or not data was received since the last timeout, to account for an abnormal disconnection after data was received since the last timeout. The latter method will therefore detect an inactive session sooner than the former; by one timeout period to be exact. The remaining questions are after how many failed timeouts RT will terminate the PPP session, and whether not it uses the data check option.

Cheers.
User avatar
thechief
RouterTech Team
RouterTech Team
Posts: 12067
Joined: Wed Feb 01, 2006 10:22 pm
Location: England, the Centre of Africa
Contact:

Re: Keep Alive setting

Post by thechief » Thu Apr 30, 2015 3:41 pm

Without scouring through the source code, it is hard to answer your question.
The Chief: :afro: Be sure to read the Firmware FAQ and do a Forum Search before posting!
No support via PM. Ask all questions on the open forum.
boomer
Novice
Novice
Posts: 13
Joined: Wed Jan 15, 2014 5:45 pm

Re: Keep Alive setting

Post by boomer » Fri May 01, 2015 3:17 pm

Indeed. Going by intuition though I would imagine the Keep Alive period would be the total period to wait before disconnecting, the LCP echo request period being fixed and the total retry count being adjusted for the total waiting period. So for example the default Keep Alive period of 10 minutes would mean e.g. an LCP echo request period of 30 seconds and a total retry count of 20. A Keep Alive period of 1 minute would translate to an LCP echo request period of 30 seconds and a total retry count of 2, etc.. A Keep Alive period value of 0 would presumably disable the Keep Alive function altogether (i.e. no LCP echo requests would be sent) and the PPP session would never be terminated. Whether or not the data check option is used is still up for speculation.

I guess what is meant by "the time to wait without being connected to your provider" on the help page means "the time to wait without receiving any data from your provider".

Cheers.
Post Reply