Implementing DCC with MP
In DCC applications, you can configure load thresholds for links.
If you set a link load threshold in the range of 1 to 99, MP tunes allocated bandwidth according to actual traffic percentage following these guidelines:
When the percentage of traffic on a link to bandwidth exceeds the defined traffic threshold, the system automatically brings up the second link and assigns them to an MP bundle. When the percentage of traffic on these two links to bandwidth exceeds the defined traffic threshold, the system brings up a third link, and assigns it to the MP bundle, and 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 greater than 2) links to the bandwidth of N – 1 links decreases below the defined traffic threshold, the system automatically shuts down a link, and 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 the traffic size before doing that. In addition, it does not tear down links that have been established due to timeout.
To implement MP with DCC, use dialer interfaces. The following shows how MP operates after you configure the ppp mp and dialer threshold commands on a dialer interface:
When the ratio of traffic to bandwidth on a physical interface assigned to the dialer interface exceeds the configured 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.
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 require multiple links carry services. To do so, configure the ppp mp min-bind command to enable DCC to bring up multiple links when triggered to ensure minimum bandwidth. MP operates in the following workflow:
DCC brings up the first link.
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.
When MP is used with DCC, the dialer threshold, ppp mp max-bind, and ppp mp min-bind commands must be configured in dialer interface view. When you configure other PPP commands, perform the following configurations:
In the C-DCC approach, configure PPP-related commands in dialer interface view.
In the RS-DCC approach, configure PPP-related commands in dialer interface view at the calling end and in physical dialup interface view at the called end. At the calling end, however, configure the same PPP parameters on physical dialup interfaces as well to ensure reliable PPP link negotiation.