3Com MSR 50 Series Configuration Manual page 169

Implementing DCC with MP
In DCC applications, you may configure load thresholds for links.
If you set a link load threshold in the range 1 to 99, MP tunes allocated bandwidth
according to actual traffic percentage as follows:
When the percentage of traffic on a link to bandwidth exceeds the defined
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traffic threshold, the system automatically brings up the second link, and
assigns them to one MP bundle. When the percentage of traffic on these two
links to bandwidth exceeds the defined traffic threshold, the system brings up
the third link, and assigns it to the MP bundle, so on and so forth. This ensures
appropriate traffic distribution on DCC links.
On the contrary, when the percentage of the traffic on N (which is an integer
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greater than 2) links to the bandwidth of N - 1 links decreases under the
defined traffic threshold, the system automatically shuts down a link, so on and
so forth. This ensures the efficient use of DCC links.
If you set the link load threshold to zero, DCC brings up all available links when
triggered by auto-dial or packets instead of looking at traffic size before doing
that. In addition, it does not tear down links that has been established for timeout.
To implement MP with DCC, you must use dialer interfaces. The following is how
MP operates after you configure the ppp mp and dialer threshold commands on
a dialer interface:
1 When the ratio of traffic to bandwidth on a physical interface (or a B channel)
assigned to the dialer interface exceeds the load threshold, DCC brings up another
physical interface in the dialer interface, and assigns these links to an MP bundle. If
the physical interfaces are ISDN BRI or PRI interfaces, DCC uses idle B channels on
them to form an MP bundle.
2 When the number of bundled links reaches the upper threshold specified by the
max-bind-num argument, DCC stops to bring up new links.
Some dial applications may require multiple links to carry service. To this end, you
may configure the ppp mp min-bind command, allowing DCC to bring up
multiple links when triggered to ensure minimum bandwidth. The following is
how MP operates in this case:
3 DCC brings up the first link.
4 When the first link comes up, DCC checks whether the number of links in the MP
bundle reaches the lower limit specified by the min-bind-num argument. If not,
the router brings up the second link.
This process continues until the number of links in the MP bundle reaches the
lower limit.
Note that when MP is used with DCC, the commands dialer threshold, ppp mp
max-bind, and ppp mp min-bind must be configured in dialer interface view.
When configuring other PPP commands, observe the following:
In the C-DCC approach, configure in dialer interface view.
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DCC Configuration 169