PPPoE over Fiber overhead question

Here! the bad thing is that it is in spanish. Page 22. I hope you can use google translate :-D. If not, just tell me and i can translate some parts to you. Telefonica is the main company owner of the Brand Movistar.

https://www.cnmc.es/sites/default/files/editor_contenidos/Telecomunicaciones/Ofertas/NEBA/2017_Texto%20NEBA%20Marzo%202017.pdf

About the test, it is nice that you ask. I was using the typical ping test, but i discovered that the new version of OpenVPN 2.4 has a empirical test you can activate in the config file or via command line.

--mtu-test
To empirically measure MTU on connection startup, add the --mtu-test option to your configuration. OpenVPN will send ping packets of various sizes to the remote peer and measure the largest packets which were successfully received. The --mtu-test process normally takes about 3 minutes to complete.

Reference: https://community.openvpn.net/openvpn/wiki/Openvpn24ManPage

I have a Openvpn server running in my R7800 at home (Movistar fiber). That is the remote server i usually connect to from other locations. Also i connect from home to another location with a OpenVPN server, also movistar fiber hosted, with a similar router. All routers run LEDE 17.01 snapshot.

The results of the mtu-test are published in the openvpn.log, everytime i connect.

Just tell me if you need something else!

This is interesting, i can test that, increasing little by little the overhead until reaching the sweet spot

i have a 50/50 Mbit connection

Best!

Thanks for the information, Spanish is not my forte so I guess all I can do is look at the diagrams :wink: but from looking at those I believe your interpretation to be correct.

Ah, that openvpn test looks useful, now all I need is to set up openvpn :wink:

Best Regards & Muchas Gracias

Again if you need some translation, i'll be happy to provide! :smiley:

with 39 bytes of overhead, it seems the shaper performs similar to 35. I'll try to lower it to 27 to see how it goes.

Best!

For testing the effect of the specified overhead on bufferbloat I would recomment to perform the latency probe measurements while concurrently satuarating both uplink and downlink. https://github.com/tohojo/flent/tree/master/flent is a great tool to achieve this (look at the rrul or rrul_cs8 tests).

Best Regards

Thanks!!!! :smiley:

Well hi again guys!.

After doing some tests i can say that i'm very happy with the results (using 39 bytes of overhead).
I used, as @moeller0 pointed out, the flent tool and also at the scripts provided by the bufferbloat project at:

https://www.bufferbloat.net/projects/bloat/wiki/Tests_for_Bufferbloat/

betterspeedtest.sh for speed test and for a RRUL test the netperfrunner.sh

I found some SQM cake config at this post:

with some pretty interesting tweaks by @r43k3n , but mainly for Internet Cable providers, because the tweaks are related to the link layer advanced options like tcMTU, TCtsize etc. I believe those options are for MTU > 1500 so for our "pppoe-wan" case they seem to be not elegible (pppoe MTU 1492)

Best!

These are only evaluated when use use tc_stab as LLA-method, I will at least hook up the tcMPU for cake, but ATM you will need the advanced configuration strings to tell cake about the MPU... So you are correct in that these values are not suitable for cake (just the rationale s different ;))

Best Regards

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Sorry to bring this thread again but i was wondering... i'm also on fiber with 20mb/1mb net and noticed an improve in my net after setting sqm to ethernet and 35 packet overhead.

My question is... Im using a DIR-835 behind a Huawei HG8245H which i cannot put to bridge mode (because of my ISP settings, but is using PPPoE) though i have the huawei modem in DMZ, i believe im dual natting or at least adding a hop to the network... should i increase the packet overhead or keep these settings???

Mmh, that is nice then, but does your ISP use (PPPoE and) a VLAN-tag? The point is that specifying more overhead than necessary is equivalent with a (packet-size dependent) reduction of the bandwidth and will give the shaper more leeway. Conceptually one would like to measure the real overhead and account for that and then only reduce the bandwidth until the performances/latency under load increase becomes acceptable. But 35 might actually be the correct number for your link, all I want to point out that overhead and bandwidth are not simply orthogonal to each other...

Yes, as far as I can tell you are running a dualNAT setup there. But for the overhead accounting you really only need to model/specify the overhead applicable at the bottleneck link independent on all the links before and after. (But note for many internet flows the bottleneck will be completely outside of your control, so in reality you will have trouble statically accounting for anything more remote than your direct access link, as those links are typically shared between users and over-subscribed and hence do not guarantee fixed bandwidths per user).

BTW, 20/1? That seems quite "cruel" from your ISP to not go at least 20/10... One of the advantages of fiber is that it it allows much higher upstream bandwidth than the typically way more asymmetric XDSL or DOCSIS links...

Best Regards

Yeah, you have a DualNAT setup :frowning: . DMZing the D-Link only opens all ports but the double NAT is still there. You should try to find a solution to put the huawei gateway into bridge mode, so you can configure the D-link wan interface for a pppoe wan connection. Also adding up some more "cruel" stuff, your ISP should provide you with the login/pass for the huawei gateway ...

Actually as @moeller0 said in a previous post, 35 overhead should be OK and you can test 39 if your ISP uses QinQ. If you are not sure about that 4 byte overhead difference, as @moeller0 said too, don't worry you'll notice a little bandwidth decrease but nothing to be worried about.

thanks all for your answers, yeah, applying 39 decreases bandwidth a bit.. i have the login and password for my router but the bridge and ppoe setup is first time only then it seems the settings are applied from the isp side so they become unavailable to change.. im from dominican republic and 1mb upload has been an standard for decades xD, there is up to 100mb download but it is still expensive, i could change my net to 20mb/3mb or 40mb/5mb but i feel comfortable with 1mb..

i will leave the setting at 35 packets overhead as it seems to work very well, when we have the ability to measure whats really happening on the traffic flow then i will change it.

btw, by vlan tag you mean if the modem is used for VoIP and IPTV? if so, the modem do have those settings but my contract is only for internet so i dont think the other vlan tags are active.

Well, a number of ISP simply use VLAN(s) on the access link independent of the usage, so also for internet access. That should be documented somewhere potetntially even somewhere accessible to end users :wink:

Best Regards

I've beed looking for a gpon onu on ebay so i can replace the huawei for another i can put in bridge mode, but do you think ill notice any improvement?? i really want to only have the dlink as my main thou..

also, is there any cheap gpon modem that you would recommend???

Did you try hooking up a serial cable to your Huawei?? I had to do that trick to get the “telecom admin” login instead of a “user” login. Then you can probably get it into bridge mode. As for the PPPoE login; most huawei just “hide” the password with HTML code; easy the change and view.

Older firmware huawei modems let you save (backup) the config settings; those include the required passwords/logins.

Following a tutorial for another huawei i got the PPPoE password from the html as you said, but i didn't know i could connect through serial cable... i can loging using 'root' 'admin' throu ssh and telnet, but havent found any commands to make it work in bridge mode...

how can i connect using the serial cable, can you tell me??

If you already can telnet/ssh into the modem as root you can search for a config file. Most huawei modems have “telecom” login with “advanced” settings. Don’t remember where I got mine; on my huawei modem they even blocked telnet; ftp etc. I’m not at home right now do I can’t check.

a couple of months back i tried lots of logins using telecomadmin on the web and ssh, telnet with no luck, it seems my modem has disabled those accounts as it is using a custom rom from my ISP, but with the serial cable i might be able to flash a rom with all the options, i already downloaded a rom from the huawei support site but didnt know how to flash it.

You're in luck, I found a dump file from my modem on my laptop. If you can access a console (serial, telnet, ssh) try to find a file called "romfile.cfg" in the "var" directory. That contained all the settings I needed.

For serial console, any cheap USB to 3.3v TTL serial cable should work.You have to open your modem to attach the cable. The Tx Rx Gnd are normally marked on the board.

shell is broken on my rom using telnet and ssh i can start it but no command work, maybe it works using the serial cable, i will buy one usb-serial cable after work and try if i can get that file, i saw the serial port in a picture from the router page on openwrt.

BTW, i noticed that the serial port on the huawei is 3.3v, can i use a normal usb to serial adapter and cut the serial plug and solder the cables?

Hi moeller,
Can you advise me please on whether I choose: 34, 35, or 39 for my fiber setup as the following:
Fiber router bridged by vlan to my Asus router and the internet connection has been configured from the Asus router as PPPoE with ISP logins credentials. I have adaptive QoS Enabled on my Asus router.

One note: I noticed MTU best set to 1500 since I tried 1492 and the browsing speed doesn't perform smoothly compared to 1500.