enable jumbo frames permanently

prkhr4u · 02-26-2014, 10:29 PM

I want to enable jumbo frames permanently.
Temporarily i am using:

Code:

sudo ifconfig eth0 mtu 8192

and everything is working fine,I have tested it.
But when i reboot,again the mtu size is reset to 1500.

I tried this to permanently set it :

Code:

sudo gedit /etc/network/interfaces

and added the last 6 lines:

//interfaces file
auto lo
iface lo inet loopback

iface eth0 inet static
address 192.168.0.11
network 192.168.0.0
gateway 192.168.0.255
netmask 255.255.255.0
mtu 8192

then I restart networking like this:

Code:

sudo /etc/init.d/networking restart

and reboot my system.
But now I am unable to connect to my network,says "wired network device not managed"

How to correctly enable jumbo frames permanently?
P.s.: I am directly connecting a GigE camera to a GigE network adapter (Intel 82579LM),which is 1000 Base-T compatible.Using ubuntu 12.04 (64 bit)

Ser Olmy · 02-27-2014, 01:15 AM

This isn't really a hardware problem, since you were able to successfully alter the MTU using the ifconfig command. The real question here is "where does my distribution store the jumbo frame/MTU setting", but it seems you've found the right file.

It could be as simple as the gateway setting messing thing up. 192.168.0.255 is the broadcast address for the 192.168.0.0/24 network, and cannot possibly be the gateway.

prkhr4u · 02-27-2014, 11:15 PM

I have tried to set the gateway address to my camera's IP (192.168.0.1), but still I am unable to set the mtu size permanently.
Any other suggestions?

Ser Olmy · 02-28-2014, 04:28 AM

Why would you try to use an IP camera as a gateway?

But never mind that. Do you still get the same error message? Could you post the output from ifconfig eth0?

prkhr4u · 03-02-2014, 10:34 PM

Here is the output:
//setting mtu size to 8192 and running the camera

Code:

eth0      Link encap:Ethernet  HWaddr 24:be:05:23:97:e2  
          inet addr:192.168.0.11  Bcast:192.168.0.255  Mask:255.255.255.0
          inet6 addr: fe80::26be:5ff:fe23:97e2/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:8192  Metric:1
          RX packets:99637 errors:0 dropped:0 overruns:0 frame:0
          TX packets:225 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:215692740 (215.6 MB)  TX bytes:20203 (20.2 KB)
          Interrupt:20 Memory:fb100000-fb120000

//setting changes permanently in interfaces file>restart>no network found>output:

Code:

eth0	  Link encap:Ethernet  HWaddr 24:be:05:23:97:e2  
          BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)
          Interrupt:20 Memory:fb100000-fb120000

//removing settings from interfaces file> restart>network connected back to mtu 1500

Code:

eth0      Link encap:Ethernet  HWaddr 24:be:05:23:97:e2  
          inet addr:192.168.0.11  Bcast:192.168.0.255  Mask:255.255.255.0
          inet6 addr: fe80::26be:5ff:fe23:97e2/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:3 errors:0 dropped:0 overruns:0 frame:0
          TX packets:44 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:192 (192.0 B)  TX bytes:8427 (8.4 KB)
          Interrupt:20 Memory:fb100000-fb120000