continue;
}
- mtu = pch->chan->mtu - hdrlen;
+ /*
+ * hdrlen includes the 2-byte PPP protocol field, but the
+ * MTU counts only the payload excluding the protocol field.
+ * (RFC1661 Section 2)
+ */
+ mtu = pch->chan->mtu - (hdrlen - 2);
if (mtu < 4)
mtu = 4;
if (flen > mtu)