While my mp5 servers are possibly less busy (I havn't had common crashes),
I have noticed a "group" of problems.

1. The carrier dropping communication (ie: fiber cut or l2 switch breakage)
of the L2TP streams can leave mpd5 in a state where it will not die and
will not destroy interfaces (requires reboot to clear).
2. There are race conditions between quagga and mpd5 for adding/dropping
3. if A is a pppoe client and B is the mpd5 server, A cannot access TCP
services on B.  It can access tcp services _beyond_ B, but not on B. (there
is a ticket open for this).

On Wed, Oct 12, 2016 at 10:51 AM, Donald Baud via freebsd-net <
freebsd-net@freebsd.org> wrote:

> On 10/12/16 1:13 AM, Julian Elischer wrote:
>> On 11/10/2016 8:56 PM, Donald Baud via freebsd-net wrote:
>>> I've been plagued with these =daily= panics until I tried the following
>>> recipes and the server has been up for 30 days so far:
>>> Normally I should expermient more to see which one of the receipes is
>>> really the fix, but I'm just glad that the server is stable for now.
>> this is really great information.
>> It makes debugging a lot more possible.
>> I know it is a hard question, but do you have a way to simulate this
>> workload?
>> I have no real way to simulate this kind of workload
> Sadly, I don't have a way to simulate the workload but I am very
> interested to help fix these crashes since as Cassiano said, this makes
> mpd5/freebsd useless for pppoe/l2tp termination.
> At this point, I would suggest that Cassiano and Андрей confirm that they
> don't get panics when they apply the recipes that I am using.
> I am still running many other cisco-vpdn gateways that I would convert
> into mpd5/freebsd but my plan was stalled with the daily crashes.
> I'll wait a couple of weeks to be sure that my recipes are a valid
> workaround before converting my remaining cisco gateways to mpd5.
> -Dbaud
>>> recipe-1: Don't let mpd5 start automatically when server boots:
>>> i.e. in: /etc/rc.conf
>>> mpd5_enable="NO"
>>> and wait about 5 minutes after server boots then issue:
>>> /usr/local/etc/rc.d/mpd5 onestart
>>> recipe-2: recompile the kernel with the NETGRAPH_DEBUG option:
>>> options         NETGRAPH
>>> options         NETGRAPH_DEBUG
>>> options         NETGRAPH_KSOCKET
>>> options         NETGRAPH_L2TP
>>> options         NETGRAPH_SOCKET
>>> options         NETGRAPH_TEE
>>> options         NETGRAPH_VJC
>>> options         NETGRAPH_PPP
>>> options         NETGRAPH_IFACE
>>> options         NETGRAPH_MPPC_ENCRYPTION
>>> options         NETGRAPH_TCPMSS
>>> options         IPFIREWALL
>>> recipe-3: recompile the kernel and disable the IPv6 and SCTP options:
>>> nooptions       INET6
>>> nooptions       SCTP
>>> recipe-4: Don't use any of the sysctl optimizations
>>> in other words I commented out all values in sysctl.conf:
>>> # net.graph.maxdgram=20480  (this is the default)
>>> # net.graph.recvspace=20480  (this is the default)
>>> recipe-5: Don't use any of the loader.conf optimizations
>>> in other words I commented out all values in loader.conf
>>> # net.graph.maxdata=4096  (this is the default)
>>> # net.graph.maxalloc=4096 (this is the default)
>>> ================================
>>> In my case, I had the panics with 10.3 and 11-PRERELEASE
>>> 11.0-PRERELEASE FreeBSD 11.0-PRERELEASE #2 r305587
>>> With those recipes, I have been running without any crash for a month
>>> and counting.  Thats' 300 l2tp tunnels and 1400 l2tp sessions generating
>>> 700Mbit/s.
>>> -DBaud
>>> On Tuesday, October 11, 2016 7:30 AM, Cassiano Peixoto <
>>> peixotocassi...@gmail.com> wrote:
>>> Hi,
>>> There are many users complaining about this:
>>> https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=186114
>>> I've been dealing with this issue for one year with no solution. mpd5 as
>>> pppoe server on FreeBSD is useless with this bug.
>>> I really would like to see it working again, i think it's quite important
>>> to both project and many users.
>>> Thanks.
>>> On Tue, Oct 11, 2016 at 3:24 AM, Eugene Grosbein <eu...@grosbein.net>
>>> wrote:
>>> 11.10.2016 11:02, Андрей Леушкин пишет:
>>>> Hello. I have problem with "FreeBSD nas 10.3-RELEASE FreeBSD
>>>>> 10.3-RELEASE
>>>>> #0: Fri Oct  7 21:12:56 YEKT 2016 nas@nas:/usr/obj/usr/src/sys/nasv3
>>>>>    amd64"
>>>>> Kernel panic is repeated at intervals of 2-3 days. At first I thought
>>>>> that
>>>>> the problem is in the hardware, but the problem did not go away after
>>>>> replacing the server platform.
>>>>> Coredumps and more info on link
>>>>> https://drive.google.com/open?id=0BxciMy2q7ZjTTkIxem9wTE1tM2M
>>>>> Sorry for my english.
>>>>> I'll wait for an answer.
>>>>> This is known and long-stanging problem in the FreeBSD network stack.
>>>> It shows up when you have lots of network interfaced created/removed
>>>> frequently
>>>> like in your case of Network Access Server (PPtP, PPPoE etc).
>>>> Generally, people run into this problem using mpd5 network daemon.
>>>> mpd5 uses NETGRAPH kernel subsystem to process traffic and
>>>> if an interface disappears (f.e., ,user disconnected)
>>>> while kernel still processes traffic obtained from this interface, it
>>>> panices.
>>>> There were lots of reports of this problem. Noone seems to be working on
>>>> it at the moment.
>>>> You should fill a PR using Bugzilla and attach your logs to it.
>>>> Eugene Grosbein
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