Link Control Protocol options
The following options are used to configure the Link Control
Protocol for a link device:
Asynchronous control character map
The asynchronous control character map.
This is a 32-bit mask that represents control characters with
ASCII values 0 through 31. If a bit is set to 1, PPP
encodes the corresponding control character before sending it over the
link. For example, the transmission of binary data
could cause a link to hang if the value 19 (XOFF) is
sent on a link that uses software (XON/XOFF) flow control.
A map with a value
0xa0000 causes PPP to encode
for data values corresponding to both XON and XOFF.
0xffffffff encodes all control characters.
You can set the value of the map to
if the link is configured to use hardware flow control.
The final value of the map that is negotiated for use on a
link is a combination of the maps requested by each side.
Maximum receive unit size
The maximum receive unit (MRU) size
in bytes for this end of the PPP link.
Increasing this value
will generally improve performance on non-interactive
sessions as it reduces the percentage of header bytes transmitted.
The suggested value is 1500 bytes.
If the links are to be used in a multilink bundle,
it is suggested that
the MRU should be at least 6 bytes greater than the
maximum received reconstructed unit (MRRU) that
is configured in the
for outgoing connections, or in the
for incoming connections. This will prevent
fragmentation over a single link.
Use address and control field compression
Whether address and control field compression is enabled.
Use protocol field compression
Whether protocol field compression is enabled.
Negotiate magic number
Whether magic number negotiation is enabled.
The magic numbers generated by each end of a link should
be different. If they are the same, it is probable that the host
is trying to create a PPP link to itself. The usual reason for
this is that the UUCP chat script (see
has failed to log in, or PPP on the remote system has failed to
Magic number negotiation should normally be enabled.
Send LCP identification messages
Whether LCP identification messages are enabled.
© 2004 The SCO Group, Inc. All rights reserved.
UnixWare 7 Release 7.1.4 - 22 April 2004