[RP-PPPoE] PPP Bandwidth Limit at about 40Mbit

[Stefan Schick]

Hello,

we have the following Setup:

PC with PPPoE Client <---------Cat 7 Ethernet Cable ---------> PC with 
PPPoE Server

First we confirmed that all the Hardware supports Gigabit. We used 
Static IP Addresses (no PPP) and multiple parallel Http Downloads to 
prove it. We had a transfer rate of about 400 to 500 Mbit/s

After that we set up a PPP Server on one PC and a PPP Client on the 
other. Both are using rp-pppoe. For the server we used the following 
configuration: https://projects.f0i.de/linux/pppoe.md with Arch Linux as 
Operating System.

As clients we used multiple Configurations:
- Windows 7
- Fedora Linux 21
- Debian Wheezy
Each of them with the default configuration. We only entered the 
connection credentials.

No matter which client we used we only got transfer rates of about 
40Mbit/s. We expected about 400Mbit/s.

After this we got ourselves a Dsl Connection from a Provider with 
100Mbit. We confirmed this with a xDsl Measurement Test Device, the same 
the Technicians of the Provider use.

Then we tested our Linux clients on this Dsl Connection. Here we had the 
same result. Only about 40Mbit/s transfer rate. We expected 80 or 90 Mbit/s.

We also checked the "tc qdisc" entries. There was no rate limit defined. 
The entries all look like this:
## tc qdisc
qdisc fq_codel 0: dev ppp0 root refcnt 2 limit 10240p flows 1024 quantum 
1496 targetr 0.5ms interval 100.0ms ecn


For us this looks like either a bad default configuration across 
probably all Linux Distributions, or a Bug in the rp-pppoe Code. It also 
seems to affect both PPP client and server. Has anyone some ideas or a 
fix to the problem?

Regards,
Stefan Schick

-- 
Geschäftsführer


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Telefon: +49 (0) 170 / 733 64 63
E-mail: stefan.schick at cubeworksug.de
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