[Solved] Linux Network Bridge; Not passing some traffic?

[Cyker]

I've noticed that the 802.1d bridge I set up on my server isn't passing all traffic some how.

The bridge is a 3-way bridge like this:

/---- [ sky2/eth0 - 1000BaseT - Computer ]
+--- [ forcdeth/eth1 - 100BaseTx - DSL Router ]
\---- [ 3c59x/eth2 - 10Base2 - Other computers] - [ 10Base2<-> 10BaseT hub ]

Three examples of the problems I'm having:

1) The config page on a LinkSys WAG354 router - I can connect to the config page just fine directly from the server, or via a computer connected to the router directly or via. a hub/switch daisy-chained to said router.
If I try and connect to the router from either a) The coax or b) the GigE computer, it just sits there

2) Vncviewer - Same deal; Connecting to a vncserver session on the server works from all three interfaces.
However, if I run a vncserver on one of the things attached to the server and try to connect to it from another (e.g. vncserver on eth2, vncviewer on eth0) then it connects, asks for a password, but when I enter it the vnc window appears but no input is passed back, so I can't see anything.

3) Most recently: Printing to a HP JetDirect connected printer on the coax-connected hub- Again, fails to print from everything except the server, and devices conncted to either the coax or the hub.



Has anyone else come across this? I've tried a few things, but not found a way to fix it. Maybe there is a problem with my bridge config maybe? I don't think the problem is outside the server; If I unplug all three ports from the server and connect them to a mini-switch, everything works fine!

I was running iptables, but currently it is completely disabled while I'm trying to figure this out, just to make sure it is not causing the problem.

[Cyker]

Managed to track down the problem with some help from someone on #modarchive - MTU!

For some reason, the bridge had an MTU of 1492 (Perhaps something to do with the router, as 1492 is the highest MTU supported by most DSL links).

Didn't even occur to me that this could be the issue, since even multi-gigabyte SMB/CIFS, SSH and FTP transfers were still crossing okay!

Since I don't know why the bridge had an MTU of 1492, I was going to try and see if I could make the bridge fragment packets instead of silently dropping them, but apparently this is completely impossible

So the bridge is now back at 1500; Will have to wait and see if this causes any problems...!

\o/