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Upgrade 1.0.8-1 only partially solves my "silicon bug&q

Got problems with your B2 or B3? Share and get helped!
PaulW
Posts: 15
Joined: 15 Oct 2008, 15:27

Post by PaulW »

For me the command "/sbin/ifconfig eth0 mtu 1500" solved the problem too.
:lol: :lol: :lol:

Thanks
pa
Posts: 308
Joined: 06 Dec 2006, 04:38
Location: Sweden
Contact:

Post by pa »

Hi David,

Currently we are fairly certain about why the traffic was dropped, but we are struggeling to reproduce your setup in order to actually verify that our solution works.
What was your setup when you got the MTU of 576 of you WAN port?
Bubba connected directly to your cable modem?

And if you connected your windows(?) PC directly did that get 1500 as MTU?
In other words bubba and your PC did not get the same MTU?

/PA
davidI
Posts: 49
Joined: 07 Oct 2008, 13:39

Post by davidI »

pa wrote:Hi David,

Currently we are fairly certain about why the traffic was dropped, but we are struggeling to reproduce your setup in order to actually verify that our solution works.
What was your setup when you got the MTU of 576 of you WAN port?
Bubba connected directly to your cable modem?

And if you connected your windows(?) PC directly did that get 1500 as MTU?
In other words bubba and your PC did not get the same MTU?

/PA
With my Bubba directly connected to my cable modem I got an MTU of 576 on the eth0 (WAN) side.
With my PC directly connected the PC got a MTU of 1500.
If I connected the bubba via a router it got 1500 on the eth0 side.
davidI
Posts: 49
Joined: 07 Oct 2008, 13:39

Post by davidI »

pa wrote:Hi David,

Currently we are fairly certain about why the traffic was dropped, but we are struggeling to reproduce your setup in order to actually verify that our solution works.
/PA
If there is anything I can do to help test your solution, please let me know.
pa
Posts: 308
Joined: 06 Dec 2006, 04:38
Location: Sweden
Contact:

Post by pa »

Hi David,

When you connect your bubba directly to your and get the MTU of 576, could you try to run the commands (as root):

iptables -A INPUT -p icmp -m icmp --icmp-type 3/4 -j ACCEPT
iptables -A FORWARD -p icmp -m icmp --icmp-type 3/4 -j ACCEPT

This will open up the capabilites for bubba to talk to other routers for in order to fragment tcp packets.

The difference between Bubba and your PC could be that Bubba ask your router for which MTU to use, which is not always the case in all systems.
The router then provides the MTU of 576, but since it obviously can handle 1500, I would say that reporting this value is incorrect, but it should be handled in any case by Bubba.
However, since the larger MTU does work this is the preferable setting to use since larger packets most likely will give you a better performace on your internet connection.

I order to ignore the MTU reported by your modem (or more accurate, not ask for it), edit the file "/etc/dhcp3/dhclient.conf" and remove from the request "interface-mtu".

So there are two solutions for this, one is to allow the communications for regarding fragmentation, which would be the correct solution, the other one is for tweaking speeds. However this is not something that we feel comfortable with shipping, since this actually is a workaroung for limitations/bugs in other systems that we can not control.

/PA, Excito.
davidI
Posts: 49
Joined: 07 Oct 2008, 13:39

Post by davidI »

pa wrote:Hi David,

When you connect your bubba directly to your and get the MTU of 576, could you try to run the commands (as root):

iptables -A INPUT -p icmp -m icmp --icmp-type 3/4 -j ACCEPT
iptables -A FORWARD -p icmp -m icmp --icmp-type 3/4 -j ACCEPT

This will open up the capabilites for bubba to talk to other routers for in order to fragment tcp packets.

/PA, Excito.
Thanks for this. I will try it this evening and report back.

I presume that this must happen after each disconnect/reconnect on eth0 (e.g. an unplug or restart), just as the ifconfig workaround did.

I have tried, as an alternative, setting my eth1 to 576 and did experience the slow-down you referred to.
davidI
Posts: 49
Joined: 07 Oct 2008, 13:39

Post by davidI »

The following fix did not work, I'm sorry to say.
pa wrote: iptables -A INPUT -p icmp -m icmp --icmp-type 3/4 -j ACCEPT
iptables -A FORWARD -p icmp -m icmp --icmp-type 3/4 -j ACCEPT
By chance I had a power cut this afternoon, so my Bubba had rebooted on return of power into it's boot-up state. I ran the above 2 commands (by cut and paste) but could not access the internet from my PC.

The following fix does work - after a reboot the MTU is 1500 and I can internet OK
pa wrote:
In order to ignore the MTU reported by your modem (or more accurate, not ask for it), edit the file "/etc/dhcp3/dhclient.conf" and remove from the request "interface-mtu".
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