PPoE + SIP Issue/Bug [Ticket#2018031922003491]

RouterOS General
1

Sadly after over 2 weeks of waiting i have not received a proper respond from the support, it’s also quite frustrating that the very specific description of the problem is getting straight up ignored, i received various suggestions that i already said won’t work, support replied with a different thread of this forum with a completely different issue, after I replied with a description why it is definitely a different issue on march 29th i have not received any response.

The Problem

The problem probably lies in the connection tracking, interestingly enough, this only happens while using a PPoE connection, on PPTP or simple ethernet connections this issue can’t be reproduced.

In this topic the issue was already described and there is a workaround → reboot the router or create a new PPoE interface every other option (creating the connection manually, deactivate and activate session tracking and so on, please review the thread) has already been tried without success. Various RouterOS Versions have been tried!

A short summary with he most important details was provided by this post:
http://forum.mikrotik.com/t/nat-table-not-cleared-correctly/114110/1

Last but not least: today the problem also occurred while the ppoe connection was down for a couple of seconds, so it wasn’t the classic 24 hour forced disconnection. Re-initiating and rebooting the PBX didn’t help, also clearing the connection manually etc. etc. did not resolve the issue.

As a VoIP provider which uses mainly Mikrotiks at customer site, it is really frustrating to manually recreate such interfaces or reboot the Mikrotik, both kills the internet connection all over again and leads to a bad reputation at our customers. As of now we implemented a reboot script every night in order to avoid this, sadly a short downtime on a DSL line is inevitable, so we can not automate this process without resetting every connection because of this bug, also various filter rules and nat rules are bound to the ppoe interface which makes a script to create a new ppoe interface also not an viable option.

Please look into this!

2

RouterBOARD?
RouterOS version?
(RouterBOOT firmware version?)

The SIP device have static or DHCP address?
If DHCP, DHCP Lease time? Fixed DHCP address or not?
SIP ALG detailed settings (default or not?)

3

Various Devices (RB2011, hex, hap ac, crsXXXX and so on)
Various RouterOS versions (starting from 6.37.5 till the newest version)
Firmware Version: Whichever was the most recent one on the device/routeros

We have phone/PBXs with static and DHCP addresses, doesn’t matter (also i don’t know why this should matter, this only happens if the PPoE tunnel is down and back up again)
SIP ALG: Mostly it’s turned off, we tried turning it on but didn’t change the settings.

Also - as stated in my post - this thread provides even more information, a SIP-Provider in Germany and another one in Australia has the same problem. NAT table not cleared correctly sadly it got marked as “resolve” because the workaround was acceptable for the OP.

4

Try what I wrote in last reply:

http://forum.mikrotik.com/t/sip-connection-problem-cs-or-c-not-sacs/119074/1

5

Ok this seems quite interesting, could you elaborate this a bit further? I think it’s not quite the same since I’m expiriencing the problem on a single PPoE Interface.

As I discussed with support:
The problem is an old PPPoE + UDP kernel bug in Linux, the problem will get fixed with RouterOS v7 since it’s using a new kernel.

Sadly still no ETA on v7.

Just expirienced the problem again with L2TP over PPPoE, sometimes recreating the Interface doesn’t even work.

6

Our ISP who mainly works with Mikrotik as well has found a work around, you need to implement a script on the PPP profile of your ppoe interface. Implement it “On Down” - in this case pppoe-out1 uses ether1 to establish the connection (change this as you desire). 5 Seconds of delay seem to work very well for this.

:if ([/interface ethernet find name=ether1 disabled=no] !="") do={
:if ([/interface pppoe-client find name=pppoe-out1 disabled=no] !="") do={
  /interface pppoe-client disable pppoe-out1
  /interface ethernet disable ether1
  delay 3
  /interface ethernet enable ether1
  delay 2
  /interface pppoe-client enable pppoe-out1
}
}
7

Did you get anything back from MT Support?

8

“Will be fixed in v7, can’t change the fundamentals in v6”

Asked about v7 release because you know, you can always try :laughing: but yeah, no ETA