Specific router doesn't get renew_time on DHCP request

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felipepanini
Posts: 5
Joined: 11 Dec 2018, 12:35

Specific router doesn't get renew_time on DHCP request

Post by felipepanini » 11 Dec 2018, 13:35

We have been using Accel with PPPoE without any problems for quite some time. Everything works and its wonderful. But, we saw the need to change to IPoE for a bunch of reasons. By doing tests on laboratory, we came to a problem occurring with a specific router, that unfortunately corresponds to a majority of our active clients today.
The equipment is an Intelbras IWR3000N(We tested on other routers like mikrotik, tp-link, or directly to the PC, the problem doesn't happen) and the problem is the following:

The equipment receives DHCP fine, and works, but, time to time it closes its own session to start a new one, causing an internet interruption for some seconds.
By looking at this behavior closely, we identified that the equipment does not passes his vendor information during DHCP request. Then Accel passes all the DHCP information configured on the IPoE module, like IP, Mask, Gateway, lease-time, renew-time, max-lease time... And the router accepts some information and works fine with it, but it rejects the renew_time information, so, when the lease time ends, a new DHCP request occurs, and it doesn't renew itself before that happens.

For now we have been trying to see if we can change the mode that Accel passes that information in a way that the equipment can recognize, but so far we couldn't do it properly. We tried to change some parameters on the vendor dictionary, but I'm not sure if this is how we can solve the problem.

There are two wireshark files on the following link, with the DHCP communication on an Intelbras(problematic) and a TP-Link(normal), as well as the IPOE module config
Has someone maybe experienced something similar? I would appreciate some help.

dimka88
Posts: 558
Joined: 13 Oct 2014, 05:51
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Re: Specific router doesn't get renew_time on DHCP request

Post by dimka88 » 11 Dec 2018, 20:37

Hi, try use next

Code: Select all

[ipoe]
lease-time=300
renew-time=150
max-lease-time=900
set max-lease-time = lease-time*3, by default SOHO router may use 1/2 or 7/8 lease time, by RFC DHCP SOHO routers may ignore renew-time
I think you need test with netmask smaller than /16, as example /21, just try.
And I see in dump some packet encapsulated with vlan tag 1818, this is normal? Just many packet without encapsulation

felipepanini
Posts: 5
Joined: 11 Dec 2018, 12:35

Re: Specific router doesn't get renew_time on DHCP request

Post by felipepanini » 12 Dec 2018, 10:58

Hi dimka88,

The Accel server is behind a cisco switch that is currently in use for the rest of my network. To do the testing without interfering with other unwanted things, I created the vlan1818. So the communication between the server and the router occurs trough this vlan1818.
I've tried those timings before, didn't work as well. I also tried much higher values, with hope that the router would have a default renew_time, and it wouldn't need the time given by Accel, but it didn't work too. I didn't tried changing the network to from a /16 to a /21, but when I tried changing to a /30 and /32 It had the same results.
We observed SOHO routers ignoring the renew_time when we tested on the Routerboard, it generates its own renew time in a smart way, ignoring the renew_time from Accel, but it renews itself when it needs. In the other hand, the Intelbras Router doesn't do that, it just ignore the renew_time and works without this value, then, when the lease time ends, it drops the connection and start a new one. My main focus was trying to make the Accel send the information in a way that the router can understand and accepts the values given, if that is a possibility.

dimka88
Posts: 558
Joined: 13 Oct 2014, 05:51
Contact:

Re: Specific router doesn't get renew_time on DHCP request

Post by dimka88 » 12 Dec 2018, 11:07

Please capture dump (use isc-dhcp and Intelbras IWR3000N), lease update or no?
Send report to vendor Intelbras.

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