4.4. Bundle layer

This chapter describes commands that configure the bundle layer. All of these commands (except new) apply to the currently active bundle, i.e., the bundle shown at the command line prompt.

set bundle period seconds
set bundle hiwat percent
set bundle lowat percent
set bundle min-con seconds
set bundle min-dis seconds
set bundle links link1 [ ... ]

These commands are only meaningful when bandwidth management is enabled. Mpd will attempt to bring up a new link from the list specified or take down an existing link when the utilization goes above hiwat or below lowat percent, respectively. The utilization is sampled every period divided by 6 points, and is averaged over the past period seconds.

Mpd will not attempt to disconnect a link unless previous one was disconnected at least min-dis seconds before. Similarly, mpd will not open a link unless previous was opened at least min-con seconds before. These two parameters help prevent oscillations, but cause slower response time.

set bundle fsm-timeout seconds

This sets the finite state machine (FSM) retry interval for all FSM's on this bundle. This command should only be used in exceptional situations, such as doing PPP over high-latency satellite links. The default is 2 seconds.

set bundle accept option ...
set bundle deny option ...
set bundle enable option ...
set bundle disable option ...
set bundle yes option ...
set bundle no option ...

These commands configure various bundle options. Most options are bi-directional in that they can be independently enabled and disabled in each direction.

The enable and disable commands determine whether we want the corresponding option. The accept and deny commands determine whether we will allow the peer to request the corresponding option.

The yes command is the same as enable and accept. The no command is the same as disable and deny.

The options available at the bundle layer are:

bw-manage

This command enables bandwidth management, in which mpd attempts to dynamically adjust the number of connected links depending on the traffic load.

The proper functioning of bandwidth management depends on the correct latency and bandwidth information configured for each link; see the set link latency and set link bandwidth commands.

The default for this option is off -- mpd connects the links ``all or none.''

round-robin

When multilink PPP is enabled and there are two or more links connected, this option enables round robin packet scheduling across the links. That is, instead of breaking each packet into fragments and delivering the individual fragments over all the links in the bundle, each packet is delivered whole over single link. The link is chosen by rotating in round-robin fashion over all the links in the bundle.

This option normally would result in higher latency and possible delays due to TCP packets being received out of order; however, it may help in certain situations of high packet loss or broken peer equipment.

The default is disable.

ipcp

Enable/Disable IPCP negotiation. For details see the IPCP layer chapter.

The default is enable.

ipv6cp

Enable/Disable IPV6CP negotiation.

The default is disable.

compression

Enable/Disable CCP (Compression Control Protocol) negotiation. For details see the compression layer chapter.

The default is disable.

encryption

Enable/Disable ECP (Encryption Control Protocol) negotiation. For details see the encryption layer chapter.

The default is disable.

crypt-reqd

Require encryption. When encryption support is compiled into mpd, this option causes mpd to drop the link if encryption cannot be successfully negotiated in both directions. This means in effect, ``use encryption or do not connect at all.''

The default is disable.