-----Original Message----- From: Public [mailto:public-bounces@talk.mikrotik.com.au] On Behalf Of Paul Julian Sent: Wednesday, 16 August 2017 11:59 AM To: 'MikroTik Australia Public List' <public@talk.mikrotik.com.au> Subject: Re: [MT-AU Public] Strange PPPOE Problem
In this case we are the ISP and have full control over everything, nothing has changed on the backhaul or core network and straight Ethernet traffic works fine. We are setting up a lab at the moment to do more testing and the first
will test is the MSS.
I agree, MTU is really a pain in the ass, but we have found over the years
the best option is simply to let the MT Router handle it with the Change MSS setting, we have never really had issues since taking that approach except on some hotspots some years ago, but that was solved by hard setting the MSS pretty low to cover all situations and it never resurfaced.
Regards Paul
-----Original Message----- From: Public [mailto:public-bounces@talk.mikrotik.com.au] On Behalf Of Mike Everest Sent: Wednesday, 16 August 2017 11:51 AM To: 'MikroTik Australia Public List' Subject: Re: [MT-AU Public] Strange PPPOE Problem
It is always reasonable to suspect something broken in a RouterOS release unless testing rules it out ;)
MTU is a tricky issue, and it only needs a change at the DSL aggregator or ISP network to break something that has been working for ages. The fact that everything was running fine and then mysteriously stopped going points
Hmm - maybe the dslam aggregator changed something somewhere... or are you the dslam operator too? :-} thing we that pretty
squarely at either software update or MTU issue introduced by an ISP changing something with their L2 network somewhere between the DSLAM and NAS :-}
It is never easy to solve or resolve - good luck with that! ;)
Cheers!
-----Original Message----- From: Public [mailto:public-bounces@talk.mikrotik.com.au] On Behalf Of Paul Julian Sent: Wednesday, 16 August 2017 11:45 AM To: 'MikroTik Australia Public List' <public@talk.mikrotik.com.au> Subject: Re: [MT-AU Public] Strange PPPOE Problem
Hi Mike, thanks for the reply, we haven't change anything with MSS or MTU as we have been running the same setup for 3 years now at that site and nothing has changed.
We use the setting in the PPPOE profile to change the MSS for PPPOE clients so we have the mangle rule which is configuring MSS to 1440 which based on an MTU of 1480 which we run should be correct. We can see that clients are connecting with an MTU of 1480 also.
I thought the same thing as you but this configuration has been running for years and in many different sites so unless MT has broken something around the MSS in this bugfix release there shouldn't be an issue.
I'm not going to assume anything though and will try your suggestion for sure and see if it makes a difference.
Regards Paul
-----Original Message----- From: Public [mailto:public-bounces@talk.mikrotik.com.au] On Behalf Of Mike Everest Sent: Wednesday, 16 August 2017 11:13 AM To: 'MikroTik Australia Public List' Subject: Re: [MT-AU Public] Strange PPPOE Problem
Sounds a lot like MTU issue to me...
Have you tried clamping MSS to a nominally low value? We usually start at around 1200 and work up from there when this kind of thing happens.
/ip firewall mangle add protocol=tcp tcp-flags=syn action=change-mss new-mss=1200 chain=forward out-interface=pppoe-out1
Cheers!
-----Original Message----- From: Public [mailto:public-bounces@talk.mikrotik.com.au] On Behalf Of Paul Julian Sent: Wednesday, 16 August 2017 11:06 AM To: public@talk.mikrotik.com.au Subject: [MT-AU Public] Strange PPPOE Problem
Morning all, we have identified a bit of a strange issue and I was hoping that somebody might have come across it before and have some suggestions.
We run a number of sites around the place which have a fibre backhaul from our DC to the site, then a router and DSLAM at the site which supplies customers with Ethernet services. Pretty much all sites are configured in an almost identical way.
Yesterday we did a new install for a client at a site and noticed that the upload speed was slow compared to what it should be, around 9Mbit/s but fluctuating a bit. When he used the Mikrotik Bandwidth test utility and tested to the local LNS router performance was OK, however when using that app to test to a router in our DC the upload problem appeared still. The CPE was a TPLink VR600 Router running PPPOE, a common unit that we use for these installs and normally a good router. Our tech decided to go to our equipment in the building and test directly plugged into the DSLAM, there was no change when testing to the DC router, when testing to local router it was OK.
He then used the router on site which operates as the LNS running PPPOE server and is an RB1100AHx2 and connected directly to one of the spare Ethernet ports on that, configured a PPPOE server on it with the same details as the other server and the problem remained when testing to router at DC, but testing to local router was OK.
He then removed the PPPOE component and just connected normally to the Ethernet port on the router with straight IP and bandwidth tests worked fine to the local router and the DC router.
There seems to be something going on when coming from a PPPOE connection which terminates on that local router when you try uploading to something past the router, the issue never happens when uploading to the local router only outside of the network.
At this particular site we have a couple of other locations which hang off it via wireless backhauls. If we test from the local router at each of these sites back to the DC router we have no issues, so it's definitely PPPOE related.
We also have another Mikrotik router at the site which is an out of band router, when testing from this router using the same scenarios we don't have any issues. PPPOE or straight Ethernet works perfectly OK to the local router and DC router, so there is something different between using a MT router as the PPPOE client and other devices.
So far we have used a Windows 10 PC, a Macbook and a TPLink router as a CPE, they all experienced the upload problems.
We have tried disabling the MRRU setting on the PPPOE server instance, no difference. We have checked firewall rules and everything else on the router and just can't identify anything which could be causing the problem. We have tried disabling Fastpath also just in case.
We just can't find anything which seems to indicate a problem.
Currently the RB1100 is running ROS 6.37.5, it was upgraded to that bugfix version 107 days ago and we haven't noticed any issues until now.
Any suggestions would be appreciated as we have many customers connecting to this router and whilst none have complained it's surely only a matter of time.
Thanks Paul _______________________________________________ Public mailing list Public@talk.mikrotik.com.au http://talk.mikrotik.com.au/mailman/listinfo/public_talk.mikrotik.com. au
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