# Jumbo frames. What to investigate ?

## k9dog

Recently I began looking into Jumbo frames. Samba seems to be crawling around 10-12 MB/s which seems slow when disk proved it was able to do high speed on an USB3.

So the solution seemed to be to enable jumbo frames and while both hardware (at least wired) seems to be able to handle more, there doesn't seem to be any clear answers to how to set jumbo frames.

I'm afraid the network hardware is dated.

I wish it was as simple as just setting MTU to 9000 on 2 Gentoo platforms, but alas no.

The Gentoo platforms show (lspci | grep -i -E "network|ethernet")

Client:

```
02:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (rev 01)

03:00.0 Network controller: Intel Corporation PRO/Wireless 3945ABG [Golan] Network Connection (rev 02)

```

Server:

```
02:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (rev 03)

05:00.0 Network controller: Realtek Semiconductor Co., Ltd. RTL8188CE 802.11b/g/n WiFi Adapter (rev 01)

```

I think both net chips are based on RTL8168 I read somewhere depending on the company the max frame is 7200.

I also read many specify MTU 9000, but as this is bigger than the actually max frames.

I end up with more questions than answers. Looking for some suggestions to what options to set and if there is any tools/webpages that might show a little more details. I'd also like to use the wifi cards (it's currently set with MTU 1500). I can't find any frame information on the cards and I can't verify it without a lot of trial and error).

Any push in the right direction without pushing towards an abyss, would be helpful.

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## k9dog

Posting this as a reply. While I could include it in original post, it is somewhat an answer and because I prefer staying wifi on the client machine (cable connection has some trouble).

Anyway the wifi part of my question was answered by https://superuser.com/questions/1110021/jumbo-packet-can-work-in-wireless-port-as-well-as-ethernet-port and it also gives some clues to the wired part. Help on the setting up RTL8168 chips or general devices for jumbo frames and answer to what to do with less/more capable devices and maybe some help in any procedure in looking up the specs would still be appreciated.

I think it might be best to have the same MTU on all devices to avoid fragmentation and because fo the wifi limit the original MTU might be best for my mix of machines.

Not totally related, but the reason why I tried to increase network speed:

VLC would probably benefit from some kind of storage double buffering (read-ahead) that I think isn't implemented (I think it is almost run out before buffer is read) .. VLC would make a bad DVD burner (It got frame double buffering, but for samba the response time is a problem. As far as I understand it part of the problem is the lack of an acknowledge signal from the Windows platform hosting VLC. It usually leads to white screens during playbacks. Many other players handle the buffering better. I think mplayer (Windows version) and native Windows player handles it better. I haven't seen the problem on Linux clients with VLC either.

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## Ant P.

You could try NFS instead, VLC should support it. Works fast enough for me without messing with network settings:

```
 ~ $ dd if=/mnt/http-replicator/xonotic-0.8.2.zip of=/dev/null

1935636+1 records in

1935636+1 records out

991045679 bytes (991 MB, 945 MiB) copied, 8.8008 s, 113 MB/s
```

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## k9dog

I did use NFS. And on my Windows 7 Ultimate it was also included. Atm. I haven't access to that machine (need new gfx card.. old one broke).

I am considering changing to openafs, I think it got a better cache system and is available in an open release.

A bit on hold as as I fix some other issues (As I had some hardware break down on me and since my funds are lacking these days everything has become harder to realize).

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