Sorry I copy these from gitweb trunk: when lcp is up, it will call netif_set_mtu to set stack's ppp interface mtu with MIN(MIN(mtu, mru), ao->mru), but why it is followed by ppp_send_config with mtu only? the 2nd setting could be different with first setting. I can see sys-linux didn't do anything with 2nd mtu setting so it is correct, but why there is 2nd setting and with different mtu? mtu = ho->neg_mru? ho->mru: PPP_MRU; 1908 mru = go->neg_mru? MAX(wo->mru, go->mru): PPP_MRU; 1909 #ifdef HAVE_MULTILINK 1910 if (!(multilink && go->neg_mrru && ho->neg_mrru)) 1911 #endif /* HAVE_MULTILINK */ 1912 netif_set_mtu(f->unit, MIN(MIN(mtu, mru), ao->mru)); 1913 ppp_send_config(f->unit, mtu, 1914 (ho->neg_asyncmap? ho->asyncmap: 0xffffffff), 1915 ho->neg_pcompression, ho->neg_accompression); thanks, xiaozhao -- View this message in context: http://old.nabble.com/pppd%27s-mtu-setup-tp27071075p27071075.html Sent from the linux-ppp mailing list archive at Nabble.com. -- To unsubscribe from this list: send the line "unsubscribe linux-ppp" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html