pppd warnings about mtu/mru with the pppoe plugin

[Shaul Karl <shaulk@013.net>]

  Following the advice of Debian's ppp maintainer in 
changelog.Debian.gz, I am trying the rp-pppoe.so pppd plugin. So far I
was using the pppoe package. Though everything seems to work fine, it
bothers me that syslog has several warnings about

    Couldn't increase MTU to 1500
    Couldn't increase MRU to 1500

. I have tried to set the mtu and mru directives in the configuration 
file as well as ifconfig eth mtu to something, but it didn't help. 
Looking at google shows that many people got that warnings but no 
definite solution.

  Any suggestions how to fix it?

    Thank you.