On Mon, 05 Sep 2011 23:58:29 -0500, Stan Hoeppner wrote: > On 9/4/2011 5:40 AM, Camaleón wrote: >> On Wed, 31 Aug 2011 16:09:23 +0000, Camaleón wrote: >> >> (...) >> >>> I'm still monitoring this but if this is the "cure" to prevent such >>> errors, are there any expected drawbacks for lowering MTU >>> "system-wide"? > > Slightly lower overall performance when communicating with remote hosts. > Almost zero difference on the LAN.
The host is barely accesible from the LAN (just for admin tasks), it's mostly a 100% standalone and remote server which plays the role of a web server (very low traffic, it hosts a couple of dedicated sites) and e- mail services. > If you want optimal performance, you should enable jumbo frames on all > LAN hosts (9000 bytes) since you're using GbE, and install an edge > router that handles jumbo frames. Then you need not worry about any of > this. Just make sure you find out from your service provider what size > frames they use. Then program the WAN interface on the router with that > frame size (MTU). I prefer to be able to deliver all of the e-mails, performance can go to background. Anyway, I dunno if that would be possible. The switch where the server is attached to does not allow jumbo frames so I would have to completely diconnect the server from the local LAN and leave it as a purely remote server and then yes, I can enable jumbo frames for the gigabit card. But now that I know where the problem is and how can mitigate it, I doubt if that would be worth of it. > Problems such as yours are always caused by MTU mismatches. In most > cases the mismatch is between the customer's edge device and the service > provider equipment. Good routers will handle this just fine as long as > the WAN port MTU is programmed to match the service provider equipment. Yep, for what I've read, a badly configured appliance (firewall/IPS) can also give such results. > Worth noting is that different network technologies use different frame > sizes. For instance, ethernet uses a 1514 octet frame. Fiber channel > uses 2112. FDDI uses 4500. SONET is 2430. > > You mentioned a "FTTH gigabit router" previously. Is this SP equipment > or your independent equipment? As of today, it's ISP's device. FTTH was installed this summer (June- July) in the office and I'm still reluctant to make any change. > The MTU mismatch most likely exists inside that box. If it was > provided to you, then someone probably didn't program it correctly. It > should have worked fine with different MTUs on both sides. Yep, I also thought so but I couldn't find the manual of the provided device, just a very brief flyer with specs. It's a Comtrend WAP-5813n and dunno where the MTU setting is on this router nor how/if I have to tweak it. Greetings, -- Camaleón -- To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/pan.2011.09.06.13.23...@gmail.com
