On 16 April 2014 21:07, Keith Owens <[email protected]> wrote: > On 16/04/14 12:24, Toby Corkindale wrote: >> Hi, >> I posted last year about a problem I was having with Linux's PPPoE >> functionality in regards to a specific modem. At the time I put it >> down to a dodgy modem and moved on, but now I've hit it on another >> modem, and twice seems more than coincidence. >> >> The problem is that path MTU detection seem to break when the "bad" >> modems are involved. So the Linux box running pppoe is OK, because it >> knows the interface has an mtu+mru of 1492, but masqueraded clients do >> not. >> You can work around the problem a bit, by having an iptables rule with >> --clamp-mss-to-pmtu, but it's a kludge.. and importantly, only >> required for two of these four modems. The other two work just fine >> *with apparently identical configurations* (ie. LLC / bridged) >> >> Can anyone think of a reason for this? >> > Wild guess - segmentation offload. I have seen offload do really strange > things with masqueraded packets and it is just possible that the bad > modems support offload but the good modems do not. On the linux box, issue > > for interface in eth0 > do > for option in tso ufo gso gro lro > do > ethtool $interface $option off > done > done > > Replace eth0 with all the physical network interface names (eth0 eth1 etc.).
I don't have root shell access on the modems, so I can't run it there. I experimented with adjusting ethernet options last time this came up in 2013, to no effect. But thanks for the suggestion. Toby _______________________________________________ luv-main mailing list [email protected] http://lists.luv.asn.au/listinfo/luv-main
