On 26/09/13 10:48, Toby Corkindale wrote: > Hi, > This is perhaps more of a networking question than Linux, but all the > devices involved are running Linux.. > > I have what is probably a common home setup -- an ADSL modem operating > in "pure bridge" mode, connected by ethernet to a Linux server running > pppd with the PPPoE plugin. Same linux server is providing DNS, DHCP > and NAT for other clients connected via wireless and ethernet. > > This setup was running fine for many years with a Billion 7300RA ADSL > modem. I just switched it over to a newer Billion 7800NL modem in the > hope it'd provide better sync speeds on my hopeless phone line. (It > does, with some SNR tweaking) > > However for some reason path MTU discovery has completely broken when > using the newer modem. > The primary Linux box is fine, but all clients (whether wired, > wireless *or even virtual*) fail to work unless I manually set their > interfaces to an mtu of 1492. > > I'm pretty confused by this -- pppd was setting itself up with a 1492 > mtu even on the old modem, and that managed to propagate out just > fine. The only thing that changed was the modem, but that shouldn't > affect this issue. > > I'm bamboozled. Could anyone advise me on what could possibly be done > to figure out what has happened? > Or better, a way to fix it? > > Investigative notes: > 1) New router was switched back to standalone mode (where it does > pppoe, dhcp, nat etc) and in this mode, all clients worked fine. So > the ADSL link and ethernet ports seem OK. > 2) Old router was booted up to verify settings and that stuff works OK > with it. Settings for ADSL line were similar, and stuff does work with > it. (I say settings were "similar" because the two modems have > different interfaces, and the 7800NL has some extra options not > present on the 7300RA, but I don't think they're relevant to this > issue) > > Thanks in advance, > Toby >
Wild guess - TCP/UDP offload is generating bigger segments because the new modem accepts offload. On the interface that connects the server to the modem, issue ethtool -K <interface> tso off ethtool -K <interface> uso off ethtool -K <interface> gso off _______________________________________________ luv-main mailing list [email protected] http://lists.luv.asn.au/listinfo/luv-main
